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Author |
Hasnat, A. |
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Title |
Performance optimization of the nano-sized pick-up loop of a dc-SQUID |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physica C-Superconductivity And Its Applications |
Abbreviated Journal |
Physica C |
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Volume |
583 |
Issue |
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Pages |
1353852 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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A flux transformer, consisting of a superconducting primary loop (pick-up loop) in series with a superconducting secondary loop on which measurement is done, is considered to optimize the approach and sensitivity of the Superconducting QUantum Interference Device (SQUID). Performance of such a pick-up loop placed above a magnetic particle is investigated using the numerical Ginzburg-Landau (GL) simulations. By solving 3D GL equations, static properties of the device such as the distribution of Cooper-pair density and the screening current in the secondary coil have been investigated as a function of the dimensions of the primary loop. Dynamic properties, such as current-voltage characteristics and flux-dependent critical current of the device have also been addressed, all leading to conclusion that smaller size pick-up loop is the first requirement for its optimal sensitivity. |
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000636420000010 |
Publication Date |
2021-03-03 |
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ISSN |
0921-4534 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.404 |
Times cited |
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Open Access |
Not_Open_Access |
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Most recent IF: 1.404 |
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Call Number |
UA @ admin @ c:irua:177725 |
Serial |
7008 |
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Author |
Rodrigues Lavor, I. |
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Title |
Plasmons and electronic transport in two-dimensional materials |
Type |
Doctoral thesis |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Pages |
219 p. |
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Doctoral thesis; Condensed Matter Theory (CMT) |
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This thesis presents, in its first part, an investigation on the trembling motion of wave packets known as zitterbewegung (ZBW), in multilayer graphene, as well as in moiré excitons in twisted MoS2/WSe2 hetero-bilayers. In the last few decades, the dynamics of wave packets has been subject of many theoretical and experimental studies in various types of systems such as semiconductors, superconductors, crystalline solids and cold atoms. The discovery of graphene and moiré excitons in twisted hetero-bilayers, brought two new platforms for the investigation on time evolution of wave packets and possible observation of ZBW. This trembling motion was first theoretically predicted by Schrödinger for wave packets describing particles that obey the Dirac equation. This is exactly the case of low energy electrons in graphene, as well as of moiré exciton in twisted MoS2/WSe2 under an external applied electromagnetic field. ZBW in multilayer graphene was studied both analytically and computationally, respectively, through the Green's function and split-operator methods. In this system, it is found that ZBW depends not only on the wave packet width and initial pseudospin polarization, but also on the number of layers. Furthermore, the analytical and numerical methods proposed here allow to investigate wave packet dynamics in graphene systems with an arbitrary number of layers and arbitrary potential landscapes. For moiré excitons in twisted MoS2/WSe2 hetero-bilayers, it is shown that, analogously to other Dirac-like particles, this system also exhibits ZBW when under a perpendicular applied field. In this case, the ZBW presents long timescales that are compatible with current experimental techniques for exciton dynamics. This promotes the study of the dynamics of moiré excitons in van der Waals heterostructures as an advantageous solidstate platform to probe zitterbewegung, broadly tunable by gating and inter-layer twist angle. In the second part of this thesis, a study into graphene plasmonic in van der Waals heterostructure (vdWhs) are treated in a linear response framework within the Random Phase Approximation and with support of the quantum electrostatic heterostructure (QEH), a DFT-based method. Since Dirac plasmons in graphene are very sensitive to the dielectric properties of the environment, it is possible to explore this property to probe the structure and composition of van der Waals heterostructures (vdWh) placed underneath a single graphene layer. In this way, one can achieve a layer sensitivity of a single layer and differentiate between different TMDs for heterostructures thicker than 2 layers. As a consequence of this, study, the hybridization of Dirac plasmons in graphene with phonons of transition metal dichalcogenides (TMDs), when the materials are combined in so-called van der Waals heterostructures (vdWh) forming surface plasmon-phonon polaritons (SPPPs) are also investigated. It was found that it is possible to realize both strong and ultrastrong coupling regimes by tuning graphene’s Fermi energy and changing TMD layer number. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:181012 |
Serial |
7011 |
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Author |
Bafekry, A.; Faraji, M.; Fadlallah, M.M.; Mortazavi, B.; Ziabari, A.A.; Khatibani, A.B.; Nguyen, C., V; Ghergherehchi, M.; Gogova, D. |
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Title |
Point defects in a two-dimensional ZnSnN₂ nanosheet : a first-principles study on the electronic and magnetic properties |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Journal Of Physical Chemistry C |
Abbreviated Journal |
J Phys Chem C |
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Volume |
125 |
Issue |
23 |
Pages |
13067-13075 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The reduction of dimensionality is a very effective way to achieve appealing properties in two-dimensional materials (2DMs). First-principles calculations can greatly facilitate the prediction of 2DM properties and find possible approaches to enhance their performance. We employed first-principles calculations to gain insight into the impact of different types of point defects (vacancies and substitutional dopants) on the electronic and magnetic properties of a ZnSnN2 (ZSN) monolayer. We show that Zn, Sn, and N + Zn vacancy-defected structures are p-type conducting, while the defected ZSN with a N vacancy is n-type conducting. For substitutional dopants, we found that all doped structures are thermally and energetically stable. The most stable structure is found to be B-doping at the Zn site. The highest work function value (5.0 eV) has been obtained for Be substitution at the Sn site. Li-doping (at the Zn site) and Be-doping (at the Sn site) are p-type conducting, while B-doping (at the Zn site) is n-type conducting. We found that the considered ZSN monolayer-based structures with point defects are magnetic, except those with the N vacancy defects and Be-doped structures. The ab initio molecular dynamics simulations confirm that all substitutionally doped and defected structures are thermally stable. Thus, our results highlight the possibility of tuning the magnetism in ZnSnN2 monolayers through defect engineering. |
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000664312500063 |
Publication Date |
2021-06-03 |
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ISSN |
1932-7447; 1932-7455 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.536 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 4.536 |
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Call Number |
UA @ admin @ c:irua:179741 |
Serial |
7012 |
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Author |
Bafekry, A.; Faraji, M.; Fadlallah, M.M.; Jappor, H.R.; Hieu, N.N.; Ghergherehchi, M.; Feghhi, S.A.H.; Gogova, D. |
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Title |
Prediction of two-dimensional bismuth-based chalcogenides Bi₂X₃(X = S, Se, Te) monolayers with orthorhombic structure : a first-principles study |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Journal Of Physics D-Applied Physics |
Abbreviated Journal |
J Phys D Appl Phys |
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Volume |
54 |
Issue |
39 |
Pages |
395103 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
First-principles calculation is a very powerful tool for discovery and design of novel two-dimensional materials with unique properties needed for the next generation technology. Motivated by the successful preparation of Bi2S3 nanosheets with orthorhombic structure in the last year, herein we gain a deep theoretical insight into the crystal structure, stability, electronic and optical properties of Bi2X3 (X = S, Se, Te) monolayers of orthorhombic phase employing the first-principles calculations. The Molecular dynamics study, phonon spectra, criteria for elastic stability, and cohesive energy results confirm the desired stability of the Bi2X3 monolayers. From S, to Se and Te, the work function value as well as stability of the systems decrease due to the decline in electronegativity. Mechanical properties study reveals that Bi2X3 monolayers have brittle nature. The electronic bandgap values of Bi2S3, Bi2Se3 and Bi2Te3 monolayers are predicted by the HSE06 functional to be 2.05, 1.20 and 1.16 eV, respectively. By assessing the optical properties, it has been found that Bi2X3 monolayers can absorb ultraviolet light. The high in-plane optical anisotropy offers an additional degree of freedom in the design of optical devices. The properties revealed in our survey will stimulate and inspire the search for new approaches of orthorhombic Bi2X3 (X = S, Se, Te) monolayers synthesis and properties manipulation for fabrication of novel nanoelectronic and optoelectronic devices. |
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Wos |
000674464700001 |
Publication Date |
2021-07-06 |
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ISSN |
0022-3727 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.588 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Most recent IF: 2.588 |
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Call Number |
UA @ admin @ c:irua:179863 |
Serial |
7014 |
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Author |
Juneja, R.; Thebaud, S.; Pandey, T.; Polanco, C.A.; Moseley, D.H.; Manley, M.E.; Cheng, Y.Q.; Winn, B.; Abernathy, D.L.; Hermann, R.P.; Lindsay, L. |
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Title |
Quasiparticle twist dynamics in non-symmorphic materials |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Materials Today Physics |
Abbreviated Journal |
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Volume |
21 |
Issue |
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Pages |
100548 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Quasiparticle physics underlies our understanding of the microscopic dynamical behaviors of materials that govern a vast array of properties, including structural stability, excited states and interactions, dynamical structure factors, and electron and phonon conductivities. Thus, understanding band structures and quasiparticle interactions is foundational to the study of condensed matter. Here we advance a 'twist' dynamical description of quasiparticles (including phonons and Bloch electrons) in nonsymmorphic chiral and achiral materials. Such materials often have structural complexity, strong thermal resistance, and efficient thermoelectric performance for waste heat capture and clean refrigeration technologies. The twist dynamics presented here provides a novel perspective of quasiparticle behaviors in such complex materials, in particular highlighting how non-symmorphic symmetries determine band crossings and anti-crossings, topological behaviors, quasiparticle interactions that govern transport, and observables in scattering experiments. We provide specific context via neutron scattering measurements and first-principles calculations of phonons and electrons in chiral tellurium dioxide. Building twist symmetries into the quasiparticle dynamics of non-symmorphic materials offers intuition into quasi particle behaviors, materials properties, and guides improved experimental designs to probe them. More specifically, insights into the phonon and electron quasiparticle physics presented here will enable materials design strategies to control interactions and transport for enhanced thermoelectric and thermal management applications. (C) 2021 Published by Elsevier Ltd. |
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Wos |
000708226400009 |
Publication Date |
2021-09-30 |
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Series Volume |
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Edition |
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ISSN |
2542-5293 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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OpenAccess |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:184040 |
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7016 |
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Bafekry, A.; Shahrokhi, M.; Shafique, A.; Jappor, H.R.; Fadlallah, M.M.; Stampfl, C.; Ghergherehchi, M.; Mushtaq, M.; Feghhi, S.A.H.; Gogova, D. |
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Semiconducting chalcogenide alloys based on the (Ge, Sn, Pb) (S, Se, Te) formula with outstanding properties : a first-principles calculation study |
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A1 Journal article |
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Year |
2021 |
Publication |
ACS Omega |
Abbreviated Journal |
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Volume |
6 |
Issue |
14 |
Pages |
9433-9441 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Very recently, a new class of the multicationic and -anionic entropy-stabilized chalcogenide alloys based on the (Ge, Sn, Pb) (S, Se, Te) formula has been successfully fabricated and characterized experimentally [Zihao Deng et al., Chem. Mater. 32, 6070 (2020)]. Motivated by the recent experiment, herein, we perform density functional theory-based first-principles calculations in order to investigate the structural, mechanical, electronic, optical, and thermoelectric properties. The calculations of the cohesive energy and elasticity parameters indicate that the alloy is stable. Also, the mechanical study shows that the alloy has a brittle nature. The GeSnPbSSeTe alloy is a semiconductor with a direct band gap of 0.4 eV (0.3 eV using spin-orbit coupling effect). The optical analysis illustrates that the first peak of Im(epsilon) for the GeSnPbSSeTe alloy along all polarization directions is located in the visible range of the spectrum which renders it a promising material for applications in optical and electronic devices. Interestingly, we find an optically anisotropic character of this system which is highly desirable for the design of polarization-sensitive photodetectors. We have accurately predicted the thermoelectric coefficients and have calculated a large power factor value of 3.7 x 10(11) W m(-1) K-2 s(-1) for p-type. The high p-type power factor is originated from the multiple valleys near the valence band maxima. The anisotropic results of the optical and transport properties are related to the specific tetragonal alloy unit cell. |
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Wos |
000640649500012 |
Publication Date |
2021-03-30 |
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2470-1343 |
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UA library record; WoS full record; WoS citing articles |
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Open Access |
OpenAccess |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178395 |
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7017 |
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van Duijn, F.; Osca, J.; Sorée, B. |
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Skyrmion elongation, duplication, and rotation by spin-transfer torque under spatially varying spin current |
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A1 Journal article |
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Year |
2021 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys Rev B |
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Volume |
104 |
Issue |
9 |
Pages |
094426 |
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A1 Journal article; Condensed Matter Theory (CMT) |
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The effect of the spatially varying spin current on a skyrmion is numerically investigated. It is shown that an inhomogeneous current density induces an elongation of the skyrmion. This elongation can be controlled using current pulses of different strength and duration. Long current pulses lead to a splitting that forms two replicas of the initial skyrmion while for short pulses the elongated skyrmion relaxes back to its initial circular state through rotation in the MHz-GHz frequency range. The frequency is dependent on the strength of the damping coefficient. |
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000704236000002 |
Publication Date |
2021-09-21 |
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ISSN |
2469-9969; 2469-9950 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
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Open Access |
OpenAccess |
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Most recent IF: 3.836 |
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Call Number |
UA @ admin @ c:irua:182467 |
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7018 |
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Maciel de Menezes, R. |
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Skyrmionics and magnonics in chiral ferromagnets : from micromagnetic to atomistic control |
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Doctoral thesis |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Pages |
222 p. |
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Doctoral thesis; Condensed Matter Theory (CMT) |
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The precise control of skyrmionics and magnonics in magnetic materials is key to the development of novel spin-based technology and information transport applications. Essentially, the inherent stability of magnetic skyrmions (provided by their topological charge) together with their extremely small size (down to a few nanometers) and the ultralow threshold current necessary to move them in nanostructures are the main advantages of skyrmionics. Not least, magnonics offers lower power consumption compared to electronics and the excitation of high frequency (sub-100~nm wavelength) magnons makes it possible for the creation of nanometric devices for ultrafast information transport. Even though extensive research has been carried out in recent years, the precise manipulation of skyrmions and spin waves (magnons) in nanostructures is not fully mastered and needs to be addressed before making functional skyrmionic and magnonic devices. In this thesis, we reveal multiple alternatives for the manipulation of skyrmions and spin-waves in different materials, such as bulk chiral magnets, heterochiral structures, magnet-supperconductor hybrids and two-dimentional magnetic materials. We make use of a multiscale model to numerically simulate the magnetic states at each considered material, from micromagnetic to atomistic control. We first explore the different nucleation mechanisms, activation energy, and the time evolution of the skyrmion formation in chiral magnetic films, crucial for the realization of skyrmion-based devices. We show that the skyrmion lattice is formed from the conical phase progressively, most probably by the formation of chiral bobbres, followed by the cylindrical growth of individual skyrmions from the film surface. That reflects a rod-like (one-dimensional) nucleation of the skyrmion phase, with an activation barrier of several electronvolts per skyrmion for the case of MnSi (Manganese monosilicide). In addition, we reveal the interesting blinking (creation-annihilation) behavior of skyrmions close to the phase boundary between the conical and skyrmion phases, where we recall that such switching between topologically distinct states has been proposed as a bit operation for information storage. Next, we discuss the motion of ferromagnetic and antiferromagnetic skyrmions in heterochiral magnets. We report the characteristic deflection of ferromagnetic skyrmions when moving across a heterochiral interface, where the extent of such deflection is tuned by the applied spin-polarized current and the magnitude of Dzyaloshinskii-Moriya interaction. Following, we show that the antiferromagnetic skyrmion achieves much higher velocities than its ferromagnetic counterpart, yet experiences far stronger confinement in nanoengineered heterochiral tracks, which reinforces antiferromagnetic skyrmions as a favorable choice for skyrmion-based devices. After that, we study the interesting coupling of magnetic skyrmions and superconducting vortices in magnet-superconductor heterostructures. We perform numerical simulations, based on experimental observations, to demonstrate that the stray field of magnetic skyrmions can nucleate antivortices in an adjacent superconducting film, giving rise to a hybrid topological object, the skyrmion-vortex pair, which harbor promising features for skyrmionics and quantum computing applications. We then explore the manipulation of a single skyrmion-vortex pair when currents are applied into both superconducting and magnetic parts of the heterostructure, which is of importance for the facilitated skyrmion guidance in racetrack applications. Afterwards, we make use of the high tunability of magnetic parameters in two-dimensional magnetic materials to reveal the rich phase diagram of exotic magnetic configurations in magnetic monolayers with suppressed nearest-neighbour exchange, where we show that several unique cycloidal, checkerboard, row-wise and spin-ice states are stabilized by the competition between the second-nearest-neighbor exchange, Dzyaloshinskii-Moriya, and dipolar interactions. Additionally, we show the coexistence of ferromagnetic and antiferromagnetic spin-cycloids, as well as novel types of skyrmions and chiral domain walls. Finally, in the last part of the thesis, we present the spin wave properties in the two-dimensional magnetic materials CrBr$3$ and CrI$3$. Using spin-dynamics simulations parametrized from first principles, we reveal that the spin wave dispersion in such materials can be tuned in a broad range of frequencies by strain-engineering, and that a designed pattern of strain, as well as structural defects (halide vacancies) can be turned useful in the design of spin-wave guides. Lastly, we discuss the realization of magnonic crystals by moiré-periodic modulation of magnetic parameters in van der Waals heterostructures, where we show that the several nanometer small periodicities in such samples are ideal for the interference of terahertz spin waves. Recalling the wide range of possibilities for manipulating spin waves in such two-dimensional materials, we therefore suggest these systems as a front-runner for prospective terahertz magnonic applications. |
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Most recent IF: NA |
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UA @ admin @ c:irua:184244 |
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7019 |
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Hoat, D.M.; Nguyen, D.K.; Bafekry, A.; Van On, V.; Ul Haq, B.; Rivas-Silva, J.F.; Cocoletzi, G.H. |
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Title |
Strain-driven modulation of the electronic, optical and thermoelectric properties of beta-antimonene monolayer : a hybrid functional study |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Materials Science In Semiconductor Processing |
Abbreviated Journal |
Mat Sci Semicon Proc |
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Volume |
131 |
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Pages |
105878 |
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A1 Journal article; Condensed Matter Theory (CMT) |
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Electronic, optical, and thermoelectric properties of the beta-antimonene (beta-Sb) monolayer under the external biaxial strain effects are fully investigated through the first-principles calculations. The studied two-dimensional (2D) system is dynamically and structurally stable as examined via phonon spectrum and cohesive energy. At equilibrium, the beta-Sb single layer exhibits an indirect band gap of 1.310 and 1.786 eV as predicted by the PBE and HSE06 functionals, respectively. Applying external strain may induce the indirect-direct gap transition and significant variation of the energy gap. The calculated optical spectra indicate the enhancement of the optical absorption in a wide energy range from infrared to ultraviolet as induced by the applied strain. In the visible and ultraviolet regime, the absorption coefficient can reach values as large as 82.700 (10(4)/cm) and 91.458 (10(4)/cm). Results suggest that the thermoelectric performance may be improved considerably by applying proper external strain with the figure of merit reaching a value of 0.665. Our work demonstrates that the external biaxial strains may be an effective method to make the beta-Sb monolayer prospective 2D material for optoelectronic and thermoelectric applications. |
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Wos |
000663422800002 |
Publication Date |
2021-04-23 |
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| |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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| |
Series Volume |
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Series Issue |
|
Edition |
|
|
| |
ISSN |
1369-8001 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
2.359 |
Times cited |
|
Open Access |
Not_Open_Access |
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| |
Notes |
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Approved |
Most recent IF: 2.359 |
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| |
Call Number |
UA @ admin @ c:irua:179565 |
Serial |
7021 |
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| Permanent link to this record |
| |
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| |
|
Author |
Bafekry, A.; Shahrokhi, M.; Yagmurcukardes, M.; Gogova, D.; Ghergherehchi, M.; Akgenc, B.; Feghhi, S.A.H. |
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| |
Title |
Surface functionalization of the honeycomb structure of zinc antimonide (ZnSb) monolayer : a first-principles study |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Surface Science |
Abbreviated Journal |
Surf Sci |
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| |
Volume |
707 |
Issue |
|
Pages |
121796 |
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| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
Structural, electronic, optic and vibrational properties of Zinc antimonide (ZnSb) monolayers and their func-tionalized (semi-fluorinated and fully chlorinated) structures are investigated by means of the first-principles calculations. The phonon dispersion curves reveal the presence of imaginary frequencies and thus confirm the dynamical instability of ZnSb monolayer. The calculated electronic band structure corroborates the metallic character with fully-relativistic calculations. Moreover, we analyze the surface functionalization effect on the structural, vibrational, and electronic properties of the pristine ZnSb monolayer. The semi-fluorinated and fully-chlorinated ZnSb monolayers are shown to be dynamically stable in contrast to the ZnSb monolayer. At the same time, semi-fluorination and fully-chlorination of ZnSb monolayer could effectively modulate the metallic elec-tronic properties of pristine ZnSb. In addition, a magnetic metal to a nonmagnetic semiconductor transition with a band gap of 1 eV is achieved via fluorination, whereas a transition to a semiconducting state with 1.4 eV band gap is found via chlorination of the ZnSb monolayer. According to the optical properties analysis, the first ab-sorption peaks of the fluorinated-and chlorinated-ZnSb monolayers along the in-plane polarization are placed in the infrared range of spectrum, while they are in the middle ultraviolet for the out-of-plane polarization. Interestingly, the optically anisotropic behavior of these novel monolayers along the in-plane polarizations is highly desirable for design of polarization-sensitive photodetectors. The results of the calculations clearly proved that the tunable electronic properties of the ZnSb monolayer can be realized by chemical functionalization for application in the next generation nanoelectronic devices. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000626633500001 |
Publication Date |
2020-12-31 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0039-6028 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
2.062 |
Times cited |
|
Open Access |
OpenAccess |
|
| |
Notes |
|
Approved |
Most recent IF: 2.062 |
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| |
Call Number |
UA @ admin @ c:irua:177623 |
Serial |
7026 |
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| Permanent link to this record |
| |
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| |
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Author |
Faraji, M.; Bafekry, A.; Fadlallah, M.M.; Molaei, F.; Hieu, N.N.; Qian, P.; Ghergherehchi, M.; Gogova, D. |
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| |
Title |
Surface modification of titanium carbide MXene monolayers (Ti₂C and Ti₃C₂) via chalcogenide and halogenide atoms |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Physical Chemistry Chemical Physics |
Abbreviated Journal |
Phys Chem Chem Phys |
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| |
Volume |
23 |
Issue |
28 |
Pages |
15319-15328 |
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| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
Inspired by the recent successful growth of Ti2C and Ti3C2 monolayers, here, we investigate the structural, electronic, and mechanical properties of functionalized Ti2C and Ti3C2 monolayers by means of density functional theory calculations. The results reveal that monolayers of Ti2C and Ti3C2 are dynamically stable metals. Phonon band dispersion calculations demonstrate that two-surface functionalization of Ti2C and Ti(3)C(2)via chalcogenides (S, Se, and Te), halides (F, Cl, Br, and I), and oxygen atoms results in dynamically stable novel functionalized monolayer materials. Electronic band dispersions and density of states calculations reveal that all functionalized monolayer structures preserve the metallic nature of both Ti2C and Ti3C2 except Ti2C-O-2, which possesses the behavior of an indirect semiconductor via full-surface oxygen passivation. In addition, it is shown that although halide passivated Ti3C2 structures are still metallic, there exist multiple Dirac-like cones around the Fermi energy level, which indicates that semi-metallic behavior can be obtained upon external effects by tuning the energy of the Dirac cones. In addition, the computed linear-elastic parameters prove that functionalization is a powerful tool in tuning the mechanical properties of stiff monolayers of bare Ti2C and Ti3C2. Our study discloses that the electronic and structural properties of Ti2C and Ti3C2 MXene monolayers are suitable for surface modification, which is highly desirable for material property engineering and device integration. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000672406800001 |
Publication Date |
2021-06-23 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
1463-9076; 1463-9084 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
4.123 |
Times cited |
|
Open Access |
OpenAccess |
|
| |
Notes |
|
Approved |
Most recent IF: 4.123 |
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| |
Call Number |
UA @ admin @ c:irua:179809 |
Serial |
7027 |
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| Permanent link to this record |
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| |
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Author |
Nguyen, D.K.; Hoat, D.M.; Bafekry, A.; Van On, V.; Rivas-Silva, J.F.; Naseri, M.; Cocoletzi, G.H. |
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Title |
Theoretical prediction of the PtOX (X = S and Se) monolayers as promising optoelectronic and thermoelectric 2D materials |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Physica E-Low-Dimensional Systems & Nanostructures |
Abbreviated Journal |
Physica E |
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| |
Volume |
131 |
Issue |
|
Pages |
114732 |
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| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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| |
Abstract |
In this paper, two new monolayers, namely PtOS and PtOSe, are theoretically predicted using first-principles calculations. Structural, electronic, optical and thermoelectric properties are explored using full-potential linearized augmented plane-wave (FP-LAPW) method and the semiclassical Boltzmann transport theory. Predicted two-dimensional (2D) materials show good dynamical, thermodynamic and structural stability. Calculated electronic structures indicate the indirect gap semiconductor nature of the PtOS and PtOSe single layers with energy gap of 1.346(2.436) and 0.978(1.978) eV as calculated with the WC(HSE06) functional, respectively. Density of states spectra and valence charge distribution maps suggest a mix of covalent and ionic characters of the chemical bonds. 2D materials at hand exhibit good absorption property in the visible regime with coefficient value reaching the order of 105/cm, even much larger in the ultraviolet, suggesting the promising optoelectronic applicability. Finally, the thermoelectric parameters including electrical conductivity, thermal conductivity, Seebeck coefficient, power factor and figure of merit are determined and analyzed. Results indicate prospective thermoelectric performance of both considered single layers as demonstrated by large figure of merit close to unity. Our work introduces two new 2D multifunctional materials that may possess potential applications in the optoelectronic and thermoelectric nano-devices. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000647410700007 |
Publication Date |
2021-03-25 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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| |
ISSN |
1386-9477 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
2.221 |
Times cited |
|
Open Access |
Not_Open_Access |
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| |
Notes |
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Approved |
Most recent IF: 2.221 |
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| |
Call Number |
UA @ admin @ c:irua:178346 |
Serial |
7030 |
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| Permanent link to this record |
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Author |
Bizindavyi, J.; Verhulst, A.S.; Sorée, B.; Vandenberghe, W.G. |
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Title |
Thermodynamic equilibrium theory revealing increased hysteresis in ferroelectric field-effect transistors with free charge accumulation |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Communications Physics |
Abbreviated Journal |
|
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| |
Volume |
4 |
Issue |
1 |
Pages |
86 |
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| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
At the core of the theoretical framework of the ferroelectric field-effect transistor (FeFET) is the thermodynamic principle that one can determine the equilibrium behavior of ferroelectric (FERRO) systems using the appropriate thermodynamic potential. In literature, it is often implicitly assumed, without formal justification, that the Gibbs free energy is the appropriate potential and that the impact of free charge accumulation can be neglected. In this Article, we first formally demonstrate that the Grand Potential is the appropriate thermodynamic potential to analyze the equilibrium behavior of perfectly coherent and uniform FERRO-systems. We demonstrate that the Grand Potential only reduces to the Gibbs free energy for perfectly non-conductive FERRO-systems. Consequently, the Grand Potential is always required for free charge-conducting FERRO-systems. We demonstrate that free charge accumulation at the FERRO interface increases the hysteretic device characteristics. Lastly, a theoretical best-case upper limit for the interface defect density D-FI is identified. The ferroelectric field-effect transistor, which has attracted much attention for application as both a highly energy-efficient logic device and a non-volatile memory device, has often been studied within the framework of equilibrium thermodynamics. Here, the authors theoretically demonstrate the importance of utilizing the correct thermodynamic potential and investigate the impact of free charge accumulation on the equilibrium performance of ferroelectric-based systems. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000645913400001 |
Publication Date |
2021-04-30 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2399-3650 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
Times cited |
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Open Access |
OpenAccess |
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| |
Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:179005 |
Serial |
7031 |
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| Permanent link to this record |
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Author |
Abdulov, N.A.; Bacchetta, A.; Baranov, S.; Martinez, A.B.; Bertone, V.; Bissolotti, C.; Candelise, V.; Banos, L.I.E.; Bury, M.; Connor, P.L.S.; Favart, L.; Guzman, F.; Hautmann, F.; Hentschinski, M.; Jung, H.; Keersmaekers, L.; Kotikov, A.; Kusina, A.; Kutak, K.; Lelek, A.; Lidrych, J.; Lipatov, A.; Lykasov, G.; Malyshev, M.; Mendizabal, M.; Prestel, S.; Barzani, S.S.; Sapeta, S.; Schmitz, M.; Signori, A.; Sorrentino, G.; Monfared, S.T.; van Hameren, A.; van Kampen, A.M.; Vanden Bemden, M.; Vladimirov, A.; Wang, Q.; Yang, H. |
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Title |
TMDlib2 and TMDplotter : a platform for 3D hadron structure studies |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur Phys J C |
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| |
Volume |
81 |
Issue |
8 |
Pages |
752 |
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| |
Keywords |
A1 Journal article; Particle Physics Group; Condensed Matter Theory (CMT) |
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Abstract |
A common library, TMDlib2, for Transverse-Momentum-Dependent distributions (TMDs) and unintegrated parton distributions (uPDFs) is described, which allows for easy access of commonly used TMDs and uPDFs, providing a three-dimensional (3D) picture of the partonic structure of hadrons. The tool TMDplotter allows for web-based plotting of distributions implemented in TMDlib2, together with collinear pdfs as available in LHAPDF. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000687163700004 |
Publication Date |
2021-08-20 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044; 1434-6052 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.331 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 5.331 |
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Call Number |
UA @ admin @ c:irua:181762 |
Serial |
7032 |
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| Permanent link to this record |
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Author |
Osca, J.; Sorée, B. |
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Title |
Torque field and skyrmion motion by spin transfer torque in a quasi-2D interface in presence of strong spin-orbit interaction |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Journal Of Applied Physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
130 |
Issue |
13 |
Pages |
133903 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We investigate the torque field and skyrmion motion at an interface between a ferromagnet hosting a skyrmion and a material with a strong spin-orbit interaction. We analyze both semiconductor materials and topological insulators using a Hamiltonian model that includes a linear term. The spin torque-inducing current is considered to flow in the single band limit; therefore, a quantum model of current is used. Skyrmion motion due to spin transfer torque proves to be more difficult in the presence of a spin-orbit interaction in the case where only interface in-plane currents are present. However, edge effects in narrow nanowires can be used to drive the skyrmion motion and to exert a limited control on its motion direction. We also show the differences and similarities between torque fields due to electric current in the many and single band limits. Published under an exclusive license by AIP Publishing. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000755090400003 |
Publication Date |
2021-10-07 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979; 1089-7550 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 2.068 |
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Call Number |
UA @ admin @ c:irua:186452 |
Serial |
7034 |
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| Permanent link to this record |
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Author |
McLachlan, G.; Majdak, P.; Reijniers, J.; Peremans, H. |
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Title |
Towards modelling active sound localisation based on Bayesian inference in a static environment |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Acta Acustica |
Abbreviated Journal |
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Volume |
5 |
Issue |
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Pages |
45 |
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Keywords |
A1 Journal article; Engineering Management (ENM); Condensed Matter Theory (CMT) |
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Abstract |
Over the decades, Bayesian statistical inference has become a staple technique for modelling human multisensory perception. Many studies have successfully shown how sensory and prior information can be combined to optimally interpret our environment. Because of the multiple sound localisation cues available in the binaural signal, sound localisation models based on Bayesian inference are a promising way of explaining behavioural human data. An interesting aspect is the consideration of dynamic localisation cues obtained through self-motion. Here we provide a review of the recent developments in modelling dynamic sound localisation with a particular focus on Bayesian inference. Further, we describe a theoretical Bayesian framework capable to model dynamic and active listening situations in humans in a static auditory environment. In order to demonstrate its potential in future implementations, we provide results from two examples of simplified versions of that framework. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000709050000001 |
Publication Date |
2021-10-21 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:182453 |
Serial |
7035 |
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| Permanent link to this record |
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Author |
Bafekry, A.; Faraji, M.; Fadlallah, M.M.; Khatibani, A.B.; Ziabari, A. abdolahzadeh; Ghergherehchi, M.; Nedaei, S.; Shayesteh, S.F.; Gogova, D. |
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Title |
Tunable electronic and magnetic properties of MoSi₂N₄ monolayer via vacancy defects, atomic adsorption and atomic doping |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Applied Surface Science |
Abbreviated Journal |
Appl Surf Sci |
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Volume |
559 |
Issue |
|
Pages |
149862 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The two dimensional MoSi2N4 (MSN) monolayer exhibiting rich physical and chemical properties was synthesized for the first time last year. We have used the spin-polarized density functional theory to study the effect of different types of point defects on the structural, electronic, and magnetic properties of the MSN monolayer. Adsorbed, substitutionally doped (at different lattice sites), and some kind of vacancies have been considered as point defects. The computational results show all defects studied decrease the MSN monolayer band gap. We found out the H-, O-, and P-doped MSN are n-type conductors. The arsenic-doped MSN, and MSN with vacancy defects have a magnetic moment. The MSN with a Si vacancy defect is a half-metallic which is favorable for spintronic applications, while the MSN with a single N vacancy or double vacancy (N + S) defects are metallic, i. e., beneficial as spin filters and chemical sensors. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000655645300001 |
Publication Date |
2021-05-01 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0169-4332 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.387 |
Times cited |
|
Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 3.387 |
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Call Number |
UA @ admin @ c:irua:179098 |
Serial |
7038 |
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| Permanent link to this record |
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Author |
Gonzalez Garcia, A. |
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Title |
Tuning the properties of group III-As in the thinnest limit : a theoretical study of single layer and 2D-heterostructures |
Type |
Doctoral thesis |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
xvii, 175 p. |
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Keywords |
Doctoral thesis; Condensed Matter Theory (CMT) |
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Abstract |
In this thesis, a first-principles research to tune the physical properties of group III-V materials in the thinnest limit is carried out. Among the different methods to tune the mechanical, electronic and magnetic properties of these graphene related materials, we use: two-dimensional (2D) multilayers, straintronics, hydrogen functionalization, and transition metal adsorption. The first part of this research is devoted to a complete characterization of the structural, electronic, mechanical and vibrational properties of 2D group III-As monolayers, obtained from density functional theory. Our findings are used to understand the contribution of the |
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Wos |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:182959 |
Serial |
7040 |
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| Permanent link to this record |
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Author |
Naseri, M.; Bafekry, A.; Faraji, M.; Hoat, D.M.; Fadlallah, M.M.; Ghergherehchi, M.; Sabbaghi, N.; Gogova, D. |
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Title |
Two-dimensional buckled tetragonal cadmium chalcogenides including CdS, CdSe, and CdTe monolayers as photo-catalysts for water splitting |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Physical Chemistry Chemical Physics |
Abbreviated Journal |
Phys Chem Chem Phys |
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Volume |
23 |
Issue |
21 |
Pages |
12226-12232 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Pure hydrogen production via water splitting is an ideal strategy for producing clean and sustainable energy. Two-dimensional (2D) cadmium chalcogenide single-layers with a tetragonal crystal structure, namely Tetra-CdX (X = S, Se, and Te) monolayers, are theoretically predicted by means of density functional theory (DFT). Their structural stability and electronic and optical properties are investigated. We find that Tetra-CdX single-layers are thermodynamically stable. Their stability decreases as we go down the 6A group in the periodic table, i.e., from X = S to Se, and Te which also means that the electronegativity decreases. All considered novel monolayers are indirect band gap semiconductors. Using the HSE06 functional the electronic band gaps of CdS, CdSe, and CdTe monolayers are predicted to be 3.10 eV, 2.97 eV, and 2.90 eV, respectively. The impact of mechanical strain on the physical properties was studied, which indicates that compressive strain increases the band gap and tensile strain decreases the band gap. The optical properties of the Tetra-CdX monolayers show the ability of these monolayers to absorb visible light. Due to the suitable band gaps and band edge positions of Tetra-CdX, these newly discovered 2D materials are promising for photocatalytic water splitting. |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000651904600001 |
Publication Date |
2021-04-30 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
1463-9076; 1463-9084 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
4.123 |
Times cited |
|
Open Access |
Not_Open_Access |
|
| |
Notes |
|
Approved |
Most recent IF: 4.123 |
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| |
Call Number |
UA @ admin @ c:irua:178378 |
Serial |
7041 |
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| Permanent link to this record |
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| |
|
Author |
Bafekry, A.; Karbasizadeh, S.; Stampfl, C.; Faraji, M.; Hoat, D.M.; Sarsari, I.A.; Feghhi, S.A.H.; Ghergherehchi, M. |
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| |
Title |
Two-dimensional Janus semiconductor BiTeCl and BiTeBr monolayers : a first-principles study on their tunable electronic properties via an electric field and mechanical strain |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Physical Chemistry Chemical Physics |
Abbreviated Journal |
Phys Chem Chem Phys |
|
| |
Volume |
23 |
Issue |
28 |
Pages |
15216-15223 |
|
| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
Motivated by the recent successful synthesis of highly crystalline ultrathin BiTeCl and BiTeBr layered sheets [Debarati Hajra et al., ACS Nano, 2020, 14, 15626], herein for the first time, we carry out a comprehensive study on the structural and electronic properties of BiTeCl and BiTeBr Janus monolayers using density functional theory (DFT) calculations. Different structural and electronic parameters including the lattice constant, bond lengths, layer thickness in the z-direction, different interatomic angles, work function, charge density difference, cohesive energy and Rashba coefficients are determined to acquire a deep understanding of these monolayers. The calculations show good stability of the studied single layers. BiTeCl and BiTeBr monolayers are semiconductors with electronic bandgaps of 0.83 and 0.80 eV, respectively. The results also show that the semiconductor-metal transformation can be induced by increasing the number of layers. In addition, the engineering of the electronic structure is also studied by applying an electric field, and mechanical uniaxial and biaxial strain. The results show a significant change of the bandgaps and that an indirect-direct band-gap transition can be induced. This study highlights the positive prospect for the application of BiTeCl and BiTeBr layered sheets in novel electronic and energy conversion systems. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
|
Wos |
000670553900001 |
Publication Date |
2021-06-16 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
1463-9076; 1463-9084 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
4.123 |
Times cited |
|
Open Access |
OpenAccess |
|
| |
Notes |
|
Approved |
Most recent IF: 4.123 |
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| |
Call Number |
UA @ admin @ c:irua:179827 |
Serial |
7042 |
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| Permanent link to this record |
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| |
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Author |
Sozen, Y.; Yagmurcukardes, M.; Sahin, H. |
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| |
Title |
Vibrational and optical identification of GeO₂ and GeO single layers : a first-principles study |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Physical Chemistry Chemical Physics |
Abbreviated Journal |
Phys Chem Chem Phys |
|
| |
Volume |
23 |
Issue |
37 |
Pages |
21307-21315 |
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| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
In the present work, the identification of two hexagonal phases of germanium oxides (namely GeO2 and GeO) through the vibrational and optical properties is reported using density functional theory calculations. While structural optimizations show that single-layer GeO2 and GeO crystallize in 1T and buckled phases, phonon band dispersions reveal the dynamical stability of each structure. First-order off-resonant Raman spectral predictions demonstrate that each free-standing single-layer possesses characteristic peaks that are representative for the identification of the germanium oxide phase. On the other hand, electronic band dispersion analysis shows the insulating and large-gap semiconducting nature of single-layer GeO2 and GeO, respectively. Moreover, optical absorption, reflectance, and transmittance spectra obtained by means of G(0)W(0)-BSE calculations reveal the existence of tightly bound excitons in each phase, displaying strong optical absorption. Furthermore, the excitonic gaps are found to be at deep UV and visible portions of the spectrum, for GeO2 and GeO crystals, with energies of 6.24 and 3.10 eV, respectively. In addition, at the prominent excitonic resonances, single-layers display high reflectivity with a zero transmittance, which is another indication of the strong light-matter interaction inside the crystal medium. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
000697364300001 |
Publication Date |
2021-09-02 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
|
Series Issue |
|
Edition |
|
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| |
ISSN |
1463-9076; 1463-9084 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
| |
Impact Factor |
4.123 |
Times cited |
|
Open Access |
Not_Open_Access |
|
| |
Notes |
|
Approved |
Most recent IF: 4.123 |
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| |
Call Number |
UA @ admin @ c:irua:181571 |
Serial |
7044 |
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| Permanent link to this record |
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Author |
Shi, W.; Pandey, T.; Lindsay, L.; Woods, L.M. |
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| |
Title |
Vibrational properties and thermal transport in quaternary chalcogenides : the case of Te-based compositions |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Physical review materials |
Abbreviated Journal |
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| |
Volume |
5 |
Issue |
4 |
Pages |
045401 |
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| |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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| |
Abstract |
Vibrational thermal properties of CuZn2InTe4, AgZn2InTe4, and Cu2CdSnTe4, derived from binary II-VI zinc-blendes, are reported based on first-principles calculations. While the chalcogenide atoms in these materials have the same lattice positions, the cation atom arrangements vary, resulting in different crystal symmetries and subsequent properties. The compositional differences have important effects on the vibrational thermal characteristics of the studied materials, which demonstrate that low-frequency optical phonons hybridize with acoustic phonons and lead to enhanced phonon-phonon scattering and low lattice thermal conductivities. The phonon density of states, mode Gruneisen parameters, and phonon scattering rates are also calculated, enabling deeper insight into the microscopic thermal conduction processes in these materials. Compositional variations drive differences among the three materials considered here; nonetheless, their structural similarities and generally low thermal conductivities (0.5-4 W/mK at room temperature) suggest that other similar II-VI zinc-blende derived materials will also exhibit similarly low values, as also corroborated by experimental data. This, combined with the versatility in designing a variety of motifs on the overall structure, makes quaternary chalcogenides interesting for thermal management and energy conversion applications that require low thermal conductivity. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000655931400005 |
Publication Date |
2021-04-01 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
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| |
ISSN |
2475-9953 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
Times cited |
|
Open Access |
Not_Open_Access |
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| |
Notes |
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Approved |
Most recent IF: NA |
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| |
Call Number |
UA @ admin @ c:irua:179140 |
Serial |
7045 |
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| Permanent link to this record |
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Author |
Charalampopoulou, E.; Lambrinou, K.; Van der Donck, T.; Paladino, B.; Di Fonzo, F.; Azina, C.; Eklund, P.; Mraz, S.; Schneider, J.M.; Schryvers, D.; Delville, R. |
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Title |
Early stages of dissolution corrosion in 316L and DIN 1.4970 austenitic stainless steels with and without anticorrosion coatings in static liquid lead-bismuth eutectic (LBE) at 500 degrees C |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Materials Characterization |
Abbreviated Journal |
Mater Charact |
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| |
Volume |
178 |
Issue |
|
Pages |
111234 |
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| |
Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
This work addresses the early stages (<= 1000 h) of the dissolution corrosion behavior of 316L and DIN 1.4970 austenitic stainless steels in contact with oxygen-poor (C-O < 10(-8) mass%), static liquid lead-bismuth eutectic (LBE) at 500 degrees C for 600-1000 h. The objective of this study was to determine the relative early-stage resistance of the uncoated steels to dissolution corrosion and to assess the protectiveness of select candidate coatings (Cr2AlC, Al2O3, V2AlxCy). The simultaneous exposure of steels with intended differences in microstructure and thermomechanical state showed the effects of steel grain size, density of annealing/deformation twins, and secondary precipitates on the steel dissolution corrosion behavior. The findings of this study provide recommendations on steel manufacturing with the aim of using the steels to construct Gen-IV lead-cooled fast reactors. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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| |
Language |
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Wos |
000752582700001 |
Publication Date |
2021-06-01 |
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| |
Series Editor |
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Series Title |
|
Abbreviated Series Title |
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| |
Series Volume |
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Series Issue |
|
Edition |
|
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| |
ISSN |
1044-5803 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
2.714 |
Times cited |
|
Open Access |
OpenAccess |
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| |
Notes |
|
Approved |
Most recent IF: 2.714 |
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| |
Call Number |
UA @ admin @ c:irua:186509 |
Serial |
7061 |
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| Permanent link to this record |
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Author |
Arslan Irmak, E. |
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| |
Title |
Modelling three-dimensional nanoparticle transformations based on quantitative transmission electron microscopy |
Type |
Doctoral thesis |
| |
Year |
2022 |
Publication |
|
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
169 p. |
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Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Abstract |
Nanomaterials are materials that have at least one dimension in the nanometer length scale, which corresponds to a billionth of a meter. When three dimensions are confined to the nanometer scale, these materials are referred to as nanoparticles. These materials are of great interest since they exhibit unique physical and chemical properties that cannot be observed for bulk systems. Due to their unique and often superior properties, nanomaterials have become central in the field of electronics, catalysis, and medicine. Moreover, they are expected to be one of the most promising systems to tackle many challenges that our society is facing, such as reducing the emission of greenhouse gases and finding effective treatments for cancer. The unique properties of nanomaterials are linked to their size, shape, structure, and composition. If one is able to measure the positions of the atoms, their chemical nature, and the bonding between them, it becomes possible to predict the physicochemical properties of nanomaterials. In this manner, the development of novel nanostructures can be triggered. However, the morphology and structure of nanomaterials are highly sensitive to the conditions for relevant applications, such as elevated temperatures or intense light illumination. Furthermore, any small change in the local structure at higher temperatures or pressures may significantly modify their performance. Hence, three-dimensional (3D) characterization of nanomaterials under application-relevant conditions is important in designing them with desired functional properties for specific applications. Among different structural characterization approaches, transmission electron microscopy (TEM) is one of the most efficient and versatile tools to investigate the structure and composition of nanomaterials since it can provide atomically resolved images, which are sensitive to the local 3D structure of the investigated sample. However, TEM only provides two-dimensional (2D) images of the 3D nanoparticle, which may lead to an incomplete understanding of their structure-property relationship. The most known and powerful technique for the 3D characterization of nanomaterials is electron tomography, where the images of a nanostructured material taken from different directions are mathematically combined to retrieve its 3D structure. Although these experiments are already state-of-the-art, 3D characterization by TEM is typically performed under ultra-high vacuum conditions and at room temperature. Such conditions are unfortunately not sufficient to understand transformations during synthesis or applications of nanomaterials. This limitation can be overcome by in situ TEM where external stimuli, such as heat, gas, and liquids, can be controllably introduced inside the TEM using specialized holders. However, there are some technical limitations to successful perform 3D in situ electron tomography experiments. For example, the long acquisition time required to collect a tilt series limits this technique when one wants to observe 3D dynamic changes with atomic resolution. A solution for this problem is the estimation of the 3D structure of nanomaterials from 2D projection images acquired along a single viewing direction. For this purpose, annular dark field scanning TEM (ADF STEM) imaging mode provides a valuable tool for quantitative structural investigation of nanomaterials from single 2D images due to its thickness and mass sensitivity. For quantitative analysis, an ADF STEM image is considered as a 2D array of pixels where relative variation of pixel intensity values is proportional to the total number of atoms and the atomic number of the elements in the sample. By applying advanced statistical approaches to these images, structural information, such as the number or types of atoms, can be retrieved with high accuracy and precision. The outcome can then be used to build a 3D starting model for energy minimization by atomistic simulations, for example, molecular dynamics simulations or the Monte Carlo method. However, this methodology needs to be further evaluated for in situ experiments. This thesis is devoted to presenting robust approaches to accurately define the 3D atomic structure of nanoparticles under application-relevant conditions and understand the mechanism behind the atomic-scale dynamics in nanoparticles in response to environmental stimuli. |
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Corporate Author |
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Thesis |
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Place of Publication |
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Wos |
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Publication Date |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
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ISBN |
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Additional Links |
UA library record |
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Impact Factor |
|
Times cited |
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Open Access |
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| |
Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:188295 |
Serial |
7063 |
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| Permanent link to this record |
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Author |
Idrissi, H.; Carrez, P.; Cordier, P. |
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Title |
On amorphization as a deformation mechanism under high stresses |
Type |
A1 Journal article |
| |
Year |
2022 |
Publication |
Current opinion in solid state and materials science |
Abbreviated Journal |
Curr Opin Solid St M |
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| |
Volume |
26 |
Issue |
1 |
Pages |
100976-17 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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| |
Abstract |
In this paper we review the work related to amorphization under mechanical stress. Beyond pressure, we highlight the role of deviatoric or shear stresses. We show that the most recent works make amorphization appear as a deformation mechanism in its own right, in particular under extreme conditions (shocks, deformations under high stresses, high strain-rates). |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000779433300002 |
Publication Date |
2022-01-13 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
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| |
ISSN |
1359-0286 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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| |
Impact Factor |
11 |
Times cited |
|
Open Access |
OpenAccess |
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| |
Notes |
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Approved |
Most recent IF: 11 |
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| |
Call Number |
UA @ admin @ c:irua:188014 |
Serial |
7064 |
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| Permanent link to this record |
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Author |
Sun, C.; Street, M.; Zhang, C.; Van Tendeloo, G.; Zhao, W.; Zhang, Q. |
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Title |
Boron structure evolution in magnetic Cr₂O₃ thin films |
Type |
A1 Journal article |
| |
Year |
2022 |
Publication |
Materials Today Physics |
Abbreviated Journal |
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| |
Volume |
27 |
Issue |
|
Pages |
100753-100757 |
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| |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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| |
Abstract |
B substituting O in antiferromagnetic Cr2O3 is known to increase the Ne ' el temperature, whereas the actual B dopant site and the corresponding functionality remains unclear due to the complicated local structure. Herein, A combination of electron energy loss spectroscopy and first-principles calculations were used to unveil B local structures in B doped Cr2O3 thin films. B was found to form either magnetic active BCr4 tetrahedra or various inactive BO3 triangles in the Cr2O3 lattice, with a* and z* bonds exhibiting unique spectral features. Identification of BO3 triangles was achieved by changing the electron momentum transfer to manipulate the differential cross section for the 1s-z* and 1s-a* transitions. Modeling the experimental spectra as a linear combination of simulated B K edges reproduces the experimental z* / a* ratios for 15-42% of the B occupying the active BCr4 structure. This result is further supported by first-principles based thermodynamic calculations. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000827323200003 |
Publication Date |
2022-06-09 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
|
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| |
ISSN |
2542-5293 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
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| |
Impact Factor |
11.5 |
Times cited |
|
Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 11.5 |
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| |
Call Number |
UA @ admin @ c:irua:189660 |
Serial |
7078 |
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| Permanent link to this record |
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Author |
Quintelier, M.; Perkisas, T.; Poppe, R.; Batuk, M.; Hendrickx, M.; Hadermann, J. |
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Title |
Determination of spinel content in cycled Li1.2Ni0.13Mn0.54Co0.13O2 using three-dimensional electron diffraction and precession electron diffraction |
Type |
A1 Journal article |
| |
Year |
2021 |
Publication |
Symmetry-Basel |
Abbreviated Journal |
Symmetry-Basel |
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| |
Volume |
13 |
Issue |
11 |
Pages |
1989-17 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM); Electron microscopy for materials research (EMAT) |
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Abstract |
Among lithium battery cathode materials, Li1.2Ni0.13Mn0.54Co0.13O2 (LR-NMC) has a high theoretical capacity, but suffers from voltage and capacity fade during cycling. This is partially ascribed to transition metal cation migration, which involves the local transformation of the honeycomb layered structure to spinel-like nano-domains. Determination of the honeycomb layered/spinel phase ratio from powder X-ray diffraction data is hindered by the nanoscale of the functional material and the domains, diverse types of twinning, stacking faults, and the possible presence of the rock salt phase. Determining the phase ratio from transmission electron microscopy imaging can only be done for thin regions near the surfaces of the crystals, and the intense beam that is needed for imaging induces the same transformation to spinel as cycling does. In this article, it is demonstrated that the low electron dose sufficient for electron diffraction allows the collection of data without inducing a phase transformation. Using calculated electron diffraction patterns, we demonstrate that it is possible to determine the volume ratio of the different phases in the particles using a pair-wise comparison of the intensities of the reflections. Using this method, the volume ratio of spinel structure to honeycomb layered structure is determined for a submicron sized crystal from experimental three-dimensional electron diffraction (3D ED) and precession electron diffraction (PED) data. Both twinning and the possible presence of the rock salt phase are taken into account. After 150 charge-discharge cycles, 4% of the volume in LR-NMC particles was transformed irreversibly from the honeycomb layered structure to the spinel structure. The proposed method would be applicable to other multi-phase materials as well. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000815310500001 |
Publication Date |
2021-10-21 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
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| |
ISSN |
2073-8994 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
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Impact Factor |
1.457 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 1.457 |
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Call Number |
UA @ admin @ c:irua:189468 |
Serial |
7080 |
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| Permanent link to this record |
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Author |
Poulain, R.; Lumbeeck, G.; Hunka, J.; Proost, J.; Savolainen, H.; Idrissi, H.; Schryvers, D.; Gauquelin, N.; Klein, A. |
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Title |
Electronic and chemical properties of nickel oxide thin films and the intrinsic defects compensation mechanism |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
ACS applied electronic materials |
Abbreviated Journal |
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Volume |
4 |
Issue |
6 |
Pages |
2718-2728 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Although largely studied, contradictory results on nickel oxide (NiO) properties can be found in the literature. We herein propose a comprehensive study that aims at leveling contradictions related to NiO materials with a focus on its conductivity, surface properties, and the intrinsic charge defects compensation mechanism with regards to the conditions preparation. The experiments were performed by in situ photo-electron spectroscopy, electron energy loss spectroscopy, and optical as well as electrical measurements on polycrystalline NiO thin films prepared under various preparation conditions by reactive sputtering. The results show that surface and bulk properties were strongly related to the deposition temperature with in particular the observation of Fermi level pinning, high work function, and unstable oxygen-rich grain boundaries for the thin films produced at room temperature but not at high temperature (>200 degrees C). Finally, this study provides substantial information about surface and bulk NiO properties enabling to unveil the origin of the high electrical conductivity of room temperature NiO thin films and also for supporting a general electronic charge compensation mechanism of intrinsic defects according to the deposition temperature. |
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Corporate Author |
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Publisher |
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Place of Publication |
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Language |
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Wos |
000819431200001 |
Publication Date |
2022-06-07 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2637-6113 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
|
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: NA |
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| |
Call Number |
UA @ admin @ c:irua:189555 |
Serial |
7081 |
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| Permanent link to this record |
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Author |
Vishwakarma, M.; Batra, Y.; Hadermann, J.; Singh, A.; Ghosh, A.; Mehta, B.R. |
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Title |
Exploring the role of graphene oxide as a co-catalyst in the CZTS photocathodes for improved photoelectrochemical properties |
Type |
A1 Journal article |
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Year |
2022 |
Publication |
ACS applied energy materials |
Abbreviated Journal |
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Volume |
5 |
Issue |
6 |
Pages |
7538-7549 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
The hydrogen evolution properties of CZTS heterostructure photocathodes are reported with graphene oxide (GO) as a co-catalyst layer coated by a drop-cast method and an Al2O3 protection layer fabricated using atomic layer deposition. In the CZTS absorber, a minor deviation from stoichiometry across the cross section of the thin film results in nanoscale growth of spurious phases, but the kesterite phase remains the dominant phase. We have investigated the band alignment parameters such as the band gap, work function, and Fermi level position that are crucial for making kesterite-based heterostructure devices. The photocurrent density in the photocathode CZTS/CdS/ZnO is found to be improved to -4.71 mAmiddotcm(-2) at -0.40 V-RHE, which is 3 times that of the pure CZTS. This enhanced photoresponse can be attributed to faster carrier separation at p-n junction regions driven by upward band bending at CZTS grain boundaries and the ZnO layer. GO as a co-catalyst over the heterostructure photocathode significantly improves the photocurrent density to -6.14 mAmiddotcm(-2) at -0.40 V-RHE by effective charge migration in the CZTS/CdS/ZnO/GO configuration, but the onset potential shifts only after application of the Al2O3 protection layer. Significant photocurrents of -29 mAmiddotcm(-2) at -0.40 V-RHE and -8 mAmiddotcm(-2) at 0 V-RHE are observed, with an onset potential of 0.7 V-RHE in CZTS/CdS/ZnO/GO/Al2O3. The heterostructure configuration and the GO co-catalyst reduce the charge-transfer resistance, while the Al2O3 top layer provides a stable photocurrent for a prolonged time (similar to 16 h). The GO co-catalyst increases the flat band potential from 0.26 to 0.46 V-RHE in CZTS/CdS/ZnO/GO, which supports the bias-induced band bending at the electrolyte-electrode interface. |
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000820418400001 |
Publication Date |
2022-05-24 |
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ISSN |
2574-0962 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.4 |
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Open Access |
Not_Open_Access |
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Approved |
Most recent IF: 6.4 |
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Call Number |
UA @ admin @ c:irua:189666 |
Serial |
7082 |
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Author |
Hao, Y.; Velpula, G.; Kaltenegger, M.; Bodlos, W.R.; Vibert, F.; Mali, K.S.; De Feyter, S.; Resel, R.; Geerts, Y.H.; Van Aert, S.; Beljonne, D.; Lazzaroni, R. |
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Title |
From 2D to 3D : bridging self-assembled monolayers to a substrate-induced polymorph in a molecular semiconductor |
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A1 Journal article |
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2022 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
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34 |
Issue |
5 |
Pages |
2238-2248 |
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A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
In this study, a new bottom-up approach is proposed to predict the crystal structure of the substrate-induced polymorph (SIP) of an archetypal molecular semiconductor. In spite of intense efforts, the formation mechanism of SIPs is still not fully understood, and predicting their crystal structure is a very delicate task. Here, we selected lead phthalocyanine (PbPc) as a prototypical molecular material because it is a highly symmetrical yet nonplanar molecule and we demonstrate that the growth and crystal structure of the PbPc SIPs can be templated by the corresponding physisorbed self-assembled molecular networks (SAMNs). Starting from SAMNs of PbPc formed at the solution/graphite interface, the structural and energetic aspects of the assembly were studied by a combination of in situ scanning tunneling microscopy and multiscale computational chemistry approach. Then, the growth of a PbPc SIP on top of the physisorbed monolayer was modeled without prior experimental knowledge, from which the crystal structure of the SIP was predicted. The theoretical prediction of the SIP was verified by determining the crystal structure of PbPc thin films using X-ray diffraction techniques, revealing the formation of a new polymorph of PbPc on the graphite substrate. This study clearly illustrates the correlation between the SAMNs and SIPs, which are traditionally considered as two separate but conceptually connected research areas. This approach is applicable to molecular materials in general to predict the crystal structure of their SIPs. |
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000812125800001 |
Publication Date |
2022-02-17 |
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ISSN |
0897-4756; 1520-5002 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.6 |
Times cited |
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Open Access |
Not_Open_Access |
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Approved |
Most recent IF: 8.6 |
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Call Number |
UA @ admin @ c:irua:189086 |
Serial |
7084 |
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