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“Voltammetric behaviour of nitroxazepine in solubilized system and biological fluids”. Jain R, Rather JA, Dwivedi A, Materials science and engineering: part C: biomimetic materials 31, 230 (2011). http://doi.org/10.1016/J.MSEC.2010.09.001
Abstract: This study reports the development and validation of sensitive and selective assay method for the determination of the antidepressant drug in solubilized system and biological fluids. Solubilized system of different surfactants including cationic, anionic and non-ionic influences the electrochemical response of drug. Addition of cationic surfactant cetrimide to the solution containing drug enhances the peak current signal while anionic and non-ionic showed an opposite effect. The current signal due to reduction process was function of concentration of nitroxazepine, pH, type of surfactant and preconcentration time at the electrode surface. The reduction process is irreversible and adsorption controlled at HMDE. Various chemical and instrumental parameters affecting the monitored electroanalytical response were investigated and optimized for niroxazepine hydrochloride determination. The proposed SWCAdSV and DPCAdSV methods are linear over the concentration range 2.0 × 10-7 5.0 × 10-9 mol/L and 6.1 × 10-7 1.0 × 10-8 mol/L with detection limit of 1.62 × 10-10 mo/L and 1.4 × 10-9 mo/L respectively. The method shows good sensitivity, selectivity, accuracy and precision that makes it very suitable for determination of nitroxazepine in pharmaceutical formulation and biological fluids.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.MSEC.2010.09.001
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“Wearable self‐powered electrochemical devices for continuous health management”. Parrilla M, De Wael K, Advanced Functional Materials 31, 2107042 (2021). http://doi.org/10.1002/ADFM.202107042
Abstract: The wearable revolution is already present in society through numerous gadgets. However, the contest remains in fully deployable wearable (bio)chemical sensing. Its use is constrained by the energy consumption which is provided by miniaturized batteries, limiting the autonomy of the device. Hence, the combination of materials and engineering efforts to develop sustainable energy management is paramount in the next generation of wearable self-powered electrochemical devices (WeSPEDs). In this direction, this review highlights for the first time the incorporation of innovative energy harvesting technologies with top-notch wearable self-powered sensors and low-powered electrochemical sensors toward battery-free and self-sustainable devices for health and wellbeing management. First, current elements such as wearable designs, electrochemical sensors, energy harvesters and storage, and user interfaces that conform WeSPEDs are depicted. Importantly, the bottlenecks in the development of WeSPEDs from an analytical perspective, product side, and power needs are carefully addressed. Subsequently, energy harvesting opportunities to power wearable electrochemical sensors are discussed. Finally, key findings that will enable the next generation of wearable devices are proposed. Overall, this review aims to bring new strategies for an energy-balanced deployment of WeSPEDs for successful monitoring of (bio)chemical parameters of the body toward personalized, predictive, and importantly, preventive healthcare.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 12.124
DOI: 10.1002/ADFM.202107042
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“Forensic analysis of synthetic cathinones on nanomaterials-based platforms : chemometric-assisted voltametric and UPLC-MS/MS investigation”. Drăgan A-M, Feier BG, Tertis M, Bodoki E, Truta F, Stefan M-G, Kiss B, Van Durme F, De Wael K, Oprean R, Cristea C, Nanomaterials 13, 2393 (2023). http://doi.org/10.3390/NANO13172393
Abstract: Synthetic cathinones (SCs) are a group of new psychoactive substances often referred to as “legal highs” or “bath salts”, being characterized by a dynamic change, new compounds continuously emerging on the market. This creates a lack of fast screening tests, making SCs a constant concern for law enforcement agencies. Herein, we present a fast and simple method for the detection of four SCs (alpha-pyrrolidinovalerophenone, N-ethylhexedrone, 4-chloroethcathinone, and 3-chloromethcathinone) based on their electrochemical profiles in a decentralized manner. In this regard, the voltametric characterization of the SCs was performed by cyclic and square wave voltammetry. The elucidation of the SCs redox pathways was successfully achieved using liquid chromatography coupled to (tandem) mass spectrometry. For the rational identification of the ideal experimental conditions, chemometric data processing was employed, considering two critical qualitative and quantitative variables: the type of the electrochemical platform and the pH of the electrolyte. The analytical figures of merit were determined on standard working solutions using the optimized method, which exhibited wide linear ranges and LODs suitable for confiscated sample screening. Finally, the performance of the method was evaluated on real confiscated samples, the resulting validation parameters being similar to those obtained with another portable device (i.e., Raman spectrometer).
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp Electrochemical and Analytical Sciences Lab (A-Sense Lab)
Impact Factor: 5.3
DOI: 10.3390/NANO13172393
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“Photo-responsive metal-organic frameworks –, design strategies and emerging applications in photocatalysis and adsorption”. Scandura G, Eid S, Alnajjar AA, Paul T, Karanikolos GN, Shetty D, Omer K, Alqerem R, Juma A, Wang H, Arafat HA, Dumee LF, Materials Advances 4, 1258 (2023). http://doi.org/10.1039/D2MA01022D
Abstract: Stimuli-responsive metal-organic frameworks (MOFs) are highly versatile porous materials with the ability to respond to different external stimuli, including temperature, pressure, pH, and light. The MOF properties can switch reversibly under specific light irradiation, opening the doors to various applications. This review focuses on design strategies to obtain photo-responsive MOFs, namely (i) encapsulation of photo-switchable molecules as guests in MOF porous structures, (ii) fabrication of MOF composites, (iii) post-synthesis modification, and (iv) synthesis of MOFs with photo-responsive ligands. The most recent reports from the literature are herein reviewed and analyzed in terms of material chemistry and performance. Comparisons between the different strategies are performed and future challenges are discussed. The critical aspect of the fatigue of photo-responsive MOFs applied for prolonged cycling of irradiation is also discussed.
Keywords: A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1039/D2MA01022D
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“Picometer-precision few-tilt ptychotomography of 2D materials”. Hofer C, Mustonen K, Skakalova V, Pennycook TJ, 2D materials 10, 035029 (2023). http://doi.org/10.1088/2053-1583/ACDD80
Abstract: From ripples to defects, edges and grain boundaries, the 3D atomic structure of 2D materials is critical to their properties. However the damage inflicted by conventional 3D analysis precludes its use with fragile 2D materials, particularly for the analysis of local defects. Here we dramatically increase the potential for precise local 3D atomic structure analysis of 2D materials, with both greatly improved dose efficiency and sensitivity to light elements. We demonstrate light atoms can now be located in complex 2D materials with picometer precision at doses 30 times lower than previously possible. Moreover we demonstrate this using WS2, in which the light atoms are practically invisible to conventional methods at low doses. The key advance is combining the concept of few tilt tomography with highly dose efficient ptychography in scanning transmission electron microscopy. We further demonstrate the method experimentally with the even more challenging and newly discovered 2D CuI, leveraging a new extremely high temporal resolution camera.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.5
DOI: 10.1088/2053-1583/ACDD80
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“Suppressing hydrogen blistering in a magnesium-rich healable laser powder bed fusion aluminum alloy analyzed by in-situ high resolution techniques”. Gheysen J, Kashiwar A, Idrissi H, Villanova J, Simar A, Materials &, design 231, 112024 (2023). http://doi.org/10.1016/J.MATDES.2023.112024
Abstract: Hydrogen blistering, i.e. precipitation of supersaturated hydrogen at elevated temperatures, increases porosity during heat treatments in 4xxx series Al alloys manufactured by laser powder bed fusion (LPBF), as demonstrated by 3D X-ray nano-imaging in AlSi12. This paper proposes the design of a healable Al alloy to suppress hydrogen blistering and improve the damage management. The strategy consists of solute atoms diffusing towards nano-voids and precipitating on their surface, thereby filling the damage sites. A new healable Al alloy was thus developed and successfully manufactured by LPBF. 3D X-ray nano-imaging evidenced that the addition of Mg in 4xxx series Al alloys suppresses the hydrogen blistering. This is expectedly due to Mg in solid solution which increases the hydrogen solubility in the Al matrix and due to the healing of these hydrogen pores. Moreover, a significant healing of voids smaller than 500 nm diameter is observed. In-situ heating inside transmission electron microscopy pointed out that Al matrix diffuses inside the fractured Mg2Si particles, thereby demonstrating the healing ability of the new alloy. This has opened the doors to development of new healable Al alloys manufactured by LPBF as well as to new post-treatments to tailor mechanical properties and microstructure without hydrogen blistering.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.4
DOI: 10.1016/J.MATDES.2023.112024
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“Total electron yield (TEY) detection mode Cr K-edge XANES spectroscopy as a direct method to probe the composition of the surface of darkened chrome yellow (PbCr1-xSxO4) and potassium chromate paints”. Monico L, d'Acapito F, Cotte M, Janssens K, Romani A, Ricci G, Miliani C, Cartechini L, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms 539, 141 (2023). http://doi.org/10.1016/J.NIMB.2023.03.040
Abstract: The darkening of chromate-pigments, including chrome yellows (PbCr1-xSxO4), is a surface phenomenon affecting late 19th-early 20th c. paintings, such as those by Van Gogh. Exploring analytical strategies that contribute to a deep understanding of darkening is therefore significant for the long-term conservation of unique masterpieces. Here, we examined the capabilities of Cr K-edge XANES spectroscopy collected at the same time in X-ray fluorescence yield (XFY) and total electron yield (TEY) detection modes to selectively study the surface composition of darkened oil paint mock-ups composed of chrome yellow (PbCr0.2S0.8O4) or potassium chromate. By discussing advantages and drawbacks in using XFY/TEY modes in relation to XFY & mu;-XANES analysis from sectioned samples, we aim at assessing if TEY-XANES spectroscopy: (i) is a selective surface method to determine the abundance of different Cr-species from paint fragments; (ii) can contribute to optimize the analytical strategy by limiting time consuming sample preparation procedures; (iii) can decrease the probability of radiation damage.
Keywords: A1 Journal article; Engineering sciences. Technology; Antwerp X-ray Imaging and Spectroscopy (AXIS)
Impact Factor: 1.3
DOI: 10.1016/J.NIMB.2023.03.040
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“Tunable magnon topology in monolayer CrI₃, under external stimuli”. Soenen M, Milošević, MV, Physical review materials 7, 084402 (2023). http://doi.org/10.1103/PHYSREVMATERIALS.7.084402
Abstract: Two-dimensional (2D) honeycomb ferromagnets, such as monolayer chromium trihalides, are predicted to behave as topological magnon insulators, characterized by an insulating bulk and topologically protected edge states, giving rise to a thermal magnon Hall effect. Here we report the behavior of the topological magnons in monolayer CrI3 under external stimuli, including biaxial and uniaxial strain, electric gating, as well as in-plane and out-of-plane magnetic field, revealing that one can thereby tailor the magnetic states as well as the size and the topology of the magnonic bandgap. These findings broaden the perspective of using 2D magnetic materials to design topological magnonic devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.4
DOI: 10.1103/PHYSREVMATERIALS.7.084402
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“Ultrascaled graphene-capped interconnects : a quantum mechanical study”. Reyntjens P, Van de Put M, Vandenberghe WG, Sorée B, Proceedings of the IEEE ... International Interconnect Technology Conference
T2 –, IEEE International Interconnect Technology Conference (IITC) / IEEE, Materials for Advanced Metallization Conference (MAM), MAY 22-25, 2023, Dresden, Germany , 1 (2023). http://doi.org/10.1109/IITC/MAM57687.2023.10154656
Abstract: In this theoretical study, we assess the impact of a graphene capping layer on the resistivity of defective, extremely scaled interconnects. We investigate the effect of graphene capping on the electronic transport in ultrascaled interconnects, in the presence of grain boundary defects in the metal layer. We compare the results obtained using our quantum mechanical model to a simple parallel-conductor model and find that the parallel-conductor model does not capture the effect of the graphene cap correctly. At 0.5 nm metal thickness, the parallel-conductor model underestimates the conductivity by 3.0% to 4.0% for single-sided and double sided graphene capping, respectively.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
DOI: 10.1109/IITC/MAM57687.2023.10154656
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“Competition between the Ni and Fe redox in the O3-NaNi1/3Fe1/3Mn1/3O2 cathode material for Na-ion batteries”. Shevchenko VA, Glazkova IS, Novichkov DA, Skvortsova I, V Sobolev A, Abakumov AM, Presniakov IA, Drozhzhin OA, V Antipov E, Chemistry of materials 35, 4015 (2023). http://doi.org/10.1021/ACS.CHEMMATER.3C00338
Abstract: Sodium-ion batteries are attracting great attention due to their low cost and abundance of sodium. The O3-type NaNi1/3Fe1/3Mn1/3O2 layered oxide material is a promising candidate for positive electrodes (cathodes) in Na-ion batteries. However, its stable electrochemical performance is restricted by the upper voltage limit of 4.0 V (vs Na/Na+), which allows for reversibly removing 0.5-0.55 Na+ per formula unit, corresponding to the capacity of 120-130 mAh.g(-1). Further reduction of sodium content inevitably accelerates capacity degradation, and this issue calls for a detailed study of the redox reactions that accompany the electrochemical (de)intercalation of a large amount of sodium. Here, we present operando and ex situ studies using powder X-ray diffraction and X-ray absorption spectroscopy combined with Fe-57 Mossbauer spectroscopy. Our approach reveals the sequence of the redox transitions that occur during the charge and discharge of O3-NaNi1/3Fe1/3Mn1/3O2. Our data show that in addition to nickel and iron cations oxidizing to M+4, a part of iron transforms into the “3 + delta” state owing to the fast electron exchange Fe3+ + Fe4+ <-> Fe4+ + Fe3+. This process freezes upon cooling the material to 35 K, producing Fe4+ cations, some of which occupy tetrahedral positions.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 8.6
DOI: 10.1021/ACS.CHEMMATER.3C00338
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“Effect of atomic mass contrast on lattice thermal conductivity : a case study for alkali halides and alkaline-earth chalcogenides”. Rakesh Roshan SC, Yedukondalu N, Pandey T, Kunduru L, Muthaiah R, Rajaboina RK, Ehm L, Parise JB, ACS applied electronic materials 5, 5852 (2023). http://doi.org/10.1021/ACSAELM.3C00759
Abstract: Lattice thermal conductivity (kappa(L)) is of great scientific interest for the development of efficient energy conversion technologies. Therefore, microscopic understanding of phonon transport is critically important for designing functional materials. In our previous study (Roshan et al., ACS Applied Energy Mater. 2021, 5, 882-896), anomalous kappa(L) trends were predicted for rocksalt alkaline-earth chalcogenides (AECs). In the present work, we extended it to alkali halides (AHs) and conducted a thorough investigation to explore the role of atomic mass contrast on lattice dynamics and phonon transport properties of 36 binary compounds (20 AHs + 16 AECs). The calculated spectral and cumulative kappa(L) reveal that low-lying optical phonon modes significantly boost kappa(L) alongside acoustic phonons in materials where the atomic mass ratio approaches unity and cophonocity nears zero. Phonon scattering rates are relatively low for materials with a mass ratio close to one, and the corresponding phonon lifetimes are higher, which enhances kappa(L). Phonon lifetimes play a critical role, outweighing phonon group velocities, in determining the anomalous trends in kappa(L) for both AHs and AECs. To further explore the role of atomic mass contrast in kappa(L), the effect of tensile lattice strain on phonon transport has also been investigated. Under tensile strain, both group velocities and phonon lifetimes decrease in the low frequency range, leading to a decrease in kappa(L). This work provides insights on how atomic mass contrast can tune the contribution of optical phonons to kappa(L) and its implications on scattering rates by either enhancing or suppressing kappa(L). These insights would aid in the selection of elements for designing new functional materials with and without atomic mass contrast to achieve relatively high and low kappa(L) values, respectively.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1021/ACSAELM.3C00759
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“Engineering green wall botanical biofiltration to abate indoor volatile organic compounds : a review on mechanisms, phyllosphere bioaugmentation, and modeling”. Alvarado-Alvarado AA, Smets W, Irga P, Denys S, Journal of hazardous materials 465, 133491 (2024). http://doi.org/10.1016/J.JHAZMAT.2024.133491
Abstract: Indoor air pollution affects the global population, especially in developed countries where people spend around 90% of their time indoors. The recent pandemic exacerbated the exposure by relying on indoor spaces and a teleworking lifestyle. VOCs are a group of indoor air pollutants with harmful effects on human health at low concentrations. It is widespread that plants can remove indoor VOCs. To this day, research has combined principles of phytoremediation, biofiltration, and bioremediation into a holistic and sustainable technology called botanical biofiltration. Overall, it is sustained that its main advantage is the capacity to break down and biodegrade pollutants using low energy input. This differs from traditional systems that transfer VOCs to another phase. Furthermore, it offers additional benefits like decreased indoor air health costs, enhanced work productivity, and well-being. However, many disparities exist within the field regarding the role of plants, substrate, and phyllosphere bacteria. Yet their role has been theorized; its stability is poorly known for an engineering approach. Previous research has not addressed the bioaugmentation of the phyllosphere to increase the performance, which could boost the system. Moreover, most experiments have studied passive potted plant systems at a lab scale using small chambers, making it difficult to extrapolate findings into tangible parameters to engineer the technology. Active systems are believed to be more efficient yet require more maintenance and knowledge expertise; besides, the impact of the active flow on the long term is not fully understood. Besides, modeling the system has been oversimplified, limiting the understanding and optimization. This review sheds light on the field’s gains and gaps, like concepts, experiments, and modeling. We believe that embracing a multidisciplinary approach encompassing experiments, multiphysics modeling, microbial community analysis, and coworking with the indoor air sector will enable the optimization of the technology and facilitate its adoption.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 13.6
DOI: 10.1016/J.JHAZMAT.2024.133491
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“Engineering of hollow periodic mesoporous organosilica nanorods for augmented hydrogen clathrate formation”. Watson G, Kummamuru NB, Verbruggen SW, Perreault P, Houlleberghs M, Martens J, Breynaert E, Van Der Voort P, Journal of materials chemistry A : materials for energy and sustainability 11, 26265 (2023). http://doi.org/10.1039/D3TA05530B
Abstract: Hydrogen (H2) storage, in the form of clathrate hydrates, has emerged as an attractive alternative to classical storage methods like compression or liquefaction. Nevertheless, the sluggish enclathration kinetics along with low gas storage capacities in bulk systems is currently impeding the progress of this technology. To this end, unstirred systems coupled with porous materials have been shown to tackle the aforementioned drawbacks. In line with this approach, the present study explores the use of hydrophobic periodic organosilica nanoparticles, later denoted as hollow ring-PMO (HRPMO), for H2 storage as clathrate hydrates under mild operating conditions (5.56 mol% THF, 7 MPa, and 265–273 K). The surface of the HRPMO nanoparticles was carefully decorated/functionalized with THF-like moieties, which are well-known promoter agents in clathrate formation when applied in classical, homogeneous systems. The study showed that, while the non-functionalized HRPMO can facilitate the formation of binary H2-THF clathrates, the incorporation of surface-bound promotor structures enhances this process. More intriguingly, tuning the concentration of these surface-bound promotor agents on the HRPMO led to a notable effect on solid-state H2 storage capacities. An increase of 3% in H2 storage capacity, equivalent to 0.26 wt%, along with a substantial increase of up to 28% in clathrate growth kinetics, was observed when an optimal loading of 0.14 mmol g−1 of promoter agent was integrated into the HRPMO framework. Overall, the findings from this study highlight that such tuning effects in the solid-state have the potential to significantly boost hydrate formation/growth kinetics and H2 storage capacities, thereby opening new avenues for the ongoing development of H2 clathrates in industrial applications.
Keywords: A1 Journal article; Engineering sciences. Technology
Impact Factor: 11.9
DOI: 10.1039/D3TA05530B
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“Molecular simulations for carbon dioxide capture in silica slit pores”. Kumar M, Sengupta A, Kummamuru NB, Materials Today: Proceedings , 1 (2023). http://doi.org/10.1016/J.MATPR.2023.04.517
Abstract: In present work, we have performed the Grand Canonical Monte Carlo (GCMC) simulations to quantify CO2 capture inside porous silica at high operating temperatures of 673.15 K and 873.15 K; and over a operating pressure range of 500 kPa – 4000 kPa that are methane steam reforming process parameters. Related chemical potential values at these thermodynamic conditions are obtained from the bulk phase simulations in the Canonical ensemble in conjunction with Widom’s insertion technique, where the CO2 has been accurately represented by TraPPE force field. Present structure of the porous silica is a single slit pore geometry of various heights (H = 20 Å, 31.6 Å, 63.2 Å and 126.5 Å), dimensions in which possible vapour-liquid equilibria for generic square well fluids has been reported in literature. Estimation of the pore-fluid interactions show a higher interaction between silica pore and adsorbed CO2 compared to the reported pore-fluid interactions between homogeneous carbon slit pore and adsorbed CO2; thus resulting in an enhancement of adsorption inside silica pores of H = 20 Å and H = 126.5 Å, which are respectively 3.5 times and 1.5 times higher than that in homogeneous carbon slit pores of same dimensions and at 673.15 K and 500 kPa. Estimated local density plots indicate the presence of structured layers due to more molecular packing, which confirms possible liquid-like and vapour-like phase coexistence of the supercritical bulk phase CO2 under confinement.
Keywords: A3 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.MATPR.2023.04.517
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“On the role of microstructural defects on precipitation, damage, and healing behavior in a novel Al-0.5Mg2Si alloy”. Kashiwar A, Arseenko M, Simar A, Idrissi H, Materials &, design 239, 112765 (2024). http://doi.org/10.1016/J.MATDES.2024.112765
Abstract: A recently developed healable Al-Mg2Si designed by the programmed damage and repair (PDR) strategy is studied considering the role microstructural defects play on precipitation, damage, and healing. The alloy incorporates sacrificial Mg2Si particles that precipitate after friction stir processing (FSP). They act as damage localization sites and are healable based on the solid-state diffusion of Al-matrix. A combination of different transmission electron microscopy (TEM) imaging techniques enabled the visualization and quantification of various crystallographic defects and the spatial distribution of Mg2Si precipitates. Intragrain nucleation is found to be the dominant mechanism for precipitation during FSP whereas grain boundaries and subgrain boundaries mainly lead to coarsening of the precipitates. The statistical and spatial analyses of the damaged particles have shown particle fracture as the dominant damage mechanism which is strongly dependent on the size and aspect ratio of the particles whereas the damage was not found to depend on the location of the precipitates within the matrix. The damaged particles are associated with dislocations accumulated around them. The interplay of these dislocations is directly visualized during healing based on in situ TEM heating which revealed recovery in the matrix as an operative mechanism during the diffusion healing of the PDR alloy.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 8.4
DOI: 10.1016/J.MATDES.2024.112765
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“Origins of heat transport anisotropy in MoTe₂, and other bulk van der Waals materials”. Li H, Pandey T, Jiang Y, Gu X, Lindsay L, Koh YK, Materials Today Physics 37, 101196 (2023). http://doi.org/10.1016/J.MTPHYS.2023.101196
Abstract: Knowledge of how heat flows anisotropically in van der Waals (vdW) materials is crucial for thermal management of emerging 2D materials devices and design of novel anisotropic thermoelectric materials. Despite the importance, anisotropic heat transport in vdW materials is yet to be systematically studied and is often presumably attributed to anisotropic speeds of sound in vdW materials due to soft interlayer bonding relative to covalent in-plane networks of atoms. In this work, we investigate the origins of the anisotropic heat transport in vdW materials, through time-domain thermoreflectance (TDTR) measurements and first-principles calculations of anisotropic thermal conductivity of three different phases of MoTe2. MoTe2 is ideal for the study due to its weak anisotropy in the speeds of sound. We find that even when the speeds of sound are roughly isotropic, the measured thermal conductivity of MoTe2 along the c-axis is 5-8 times lower than that along the in-plane axes. We derive meaningful characteristic heat capacity, phonon group velocity, and relaxation times from our first principles calculations for selected vdW materials (MoTe2, BP, h-BN, and MoS2), to assess the contributions of these factors to the anisotropic heat transport. Interestingly, we find that the main contributor to the heat transport anisotropy in vdW materials is anisotropy in heat capacity of the dominant heat-carrying phonon modes in different directions, which originates from anisotropic optical phonon dispersion and disparity in the frequency of heat-carrying phonons in different directions. The discrepancy in frequency of the heat-carrying phonons also leads to similar to 2 times larger average relaxation times in the cross-plane direction, and partially explains the apparent dependence of the anisotropic heat transport on the anisotropic speeds of sound. This work provides insight into understanding of the anisotropic heat transport in vdW materials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 11.5
DOI: 10.1016/J.MTPHYS.2023.101196
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“Soliton motion induced along ferromagnetic skyrmion chains in chiral thin nanotracks”. Souza JCB, Vizarim NP, Reichhardt CJO, Reichhardt C, Venegas PA, Journal of magnetism and magnetic materials 587, 171280 (2023). http://doi.org/10.1016/J.JMMM.2023.171280
Abstract: Using atomistic magnetic simulations we investigate the soliton motion along a pinned skyrmion chain containing an interstitial skyrmion. We find that the soliton can exhibit stable motion along the chain without a skyrmion Hall effect for an extended range of drives. Under a constant drive the solitons have a constant velocity. We also measure the skyrmion velocity-current curves and identify the signatures of different phases including a pinned phase, stable soliton motion, and quasi-free motion at higher drives where all of the skyrmions depin from the pinning centers and move along the rigid wall. In the quasi-free motion regime, the velocity is oscillatory due to the motion of the skyrmions over the pinning sites. For increasing pinning strength, the onset of soliton motion shifts to higher values of current density. We also find that for stronger pinning, the characteristic velocity-current shape is affected by the annihilation of single or multiple skyrmions in the drive interval over which the soliton motion occurs. Our results indicate that stable skyrmion soliton motion is possible and that the solitons could be used as information carriers instead of the skyrmions themselves for technological applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1016/J.JMMM.2023.171280
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“Terahertz optoelectronic properties of synthetic single crystal diamond”. Xiao H, Zhang Z, Xu W, Wang Q, Xiao Y, Ding L, Huang J, Li H, He B, Peeters FM, Diamond and related materials 139, 110266 (2023). http://doi.org/10.1016/J.DIAMOND.2023.110266
Abstract: A systematic investigation is undertaken for studying the optoelectronic properties of single crystal diamond (SCD) grown by microwave plasma chemical vapor deposition (MPCVD). It is indicated that, without intentional doping and surface treatment during the sample growth, the terahertz (THz) optical conduction in SCD is mainly affected by surface H-terminations, -OH-, O- and N-based functional groups. By using THz time-domain spectroscopy (TDS), we measure the transmittance, the complex dielectric constant and optical conductivity σ(ω) of SCD. We find that SCD does not show typical semiconductor characteristics in THz regime, where σ(ω) cannot be described rightly by the conventional Drude formula. Via fitting the real and imaginary parts of σ(ω) to the Drude-Smith formula, the ratio of the average carrier density to the effective electron mass γ = ne/m*, the electronic relaxation time τ and the electronic backscattering or localization factor can be determined optically. The temperature dependence of these parameters is examined. From the temperature dependence of γ, a metallic to semiconductor transition is observed at about T = 10 K. The temperature dependence of τ is mainly induced by electron coupling with acoustic-phonons and there is a significant effect of photon-induced electron backscattering or localization in SCD. This work demonstrates that THz TDS is a powerful technique in studying SCD which contains H-, N- and O-based bonds and has low electron density and high dc resistivity. The results obtained from this study can benefit us to gain an in-depth understanding of SCD and may provide new guidance for the application of SCD as electronic, optical and optoelectronic materials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.1
DOI: 10.1016/J.DIAMOND.2023.110266
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“Atomically deciphering the phase segregation in mixed halide perovskite”. Yang C-Q, Yin Z-W, Li W, Cui W-J, Zhou X-G, Wang L-D, Zhi R, Xu Y-Y, Tao Z-W, Sang X, Cheng Y-B, Van Tendeloo G, Hu Z-Y, Su B-L, Advanced functional materials , 1 (2024). http://doi.org/10.1002/ADFM.202400569
Abstract: Mixed-halide perovskites show promising applications in tandem solar cells owing to their adjustable bandgap. One major obstacle to their commercialization is halide phase segregation, which results in large open-circuit voltage deficiency and J-V hysteresis. However, the ambiguous interplay between structural origin and phase segregation often results in aimless and unspecific optimization strategies for the device's performance and stability. An atomic scale is directly figured out the abundant Ruddlesden-Popper anti-phase boundaries (RP-APBs) within a CsPbIBr2 polycrystalline film and revealed that phase segregation predominantly occurs at RP-APB-enriched interfaces due to the defect-mediated lattice strain. By compensating their structural lead halide, such RP-APBs are eliminated, and the decreasing of strain can be observed, resulting in the suppression of halide phase segregation. The present work provides the deciphering to precisely regulate the perovskite atomic structure for achieving photo-stable mixed halide wide-bandgap perovskites of high-efficiency tandem solar cell commercial applications. The phase segregation in mixed halide perovskite film predominantly occurs at Ruddlesden-Popper anti-phase boundaries (RP-APBs)-enriched interfaces due to the defect-mediated lattice strain. The RP-APBs defects can be eliminated by compensating for their structural lead halide deficiency, resulting in the suppression of halide phase segregation. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
DOI: 10.1002/ADFM.202400569
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“Competition of disorder and electron-phonon coupling in 2H-TaSe2-xSx (0≤x≤2) as evidenced by Raman spectroscopy”. Blagojević, J, Mijin SD, Bekaert J, Opačić, M, Liu Y, Milošević, MV, Petrović, C, Popović, ZV, Lazarević, N, Physical review materials 8, 024004 (2024). http://doi.org/10.1103/PHYSREVMATERIALS.8.024004
Abstract: The vibrational properties of 2H-TaSe<sub>2-x</sub>S<sub>x</sub> (0≤x≤2) single crystals were probed using Raman spectroscopy and density functional theory calculations. The end members revealed two out of four symmetry-predicted Raman active modes, together with the pronounced two-phonon structure, attributable to the enhanced electron-phonon coupling. Additional peaks become observable due to crystallographic disorder for the doped samples. The evolution of the E<sub>2</sub>g<sup>2</sup> mode Fano parameter reveals that the disorder has a weak impact on electron-phonon coupling, which is also supported by the persistence of two-phonon structure in doped samples. As such, this research provides thorough insights into the lattice properties, the effects of crystallographic disorder on Raman spectra, and the interplay of this disorder with the electron-phonon coupling in 2H-TaSe<sub>2-x</sub>S<sub>x</sub> compounds.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.4
DOI: 10.1103/PHYSREVMATERIALS.8.024004
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“Enhanced electrical properties of Bi2-xSbxTe3 nanoflake thin films through interface engineering”. Wu X, Ding J, Cui W, Lin W, Xue Z, Yang Z, Liu J, Nie X, Zhu W, Van Tendeloo G, Sang X, Energy &, environment materials , e12755 (2024). http://doi.org/10.1002/EEM2.12755
Abstract: The structure-property relationship at interfaces is difficult to probe for thermoelectric materials with a complex interfacial microstructure. Designing thermoelectric materials with a simple, structurally-uniform interface provides a facile way to understand how these interfaces influence the transport properties. Here, we synthesized Bi2-xSbxTe3 (x = 0, 0.1, 0.2, 0.4) nanoflakes using a hydrothermal method, and prepared Bi2-xSbxTe3 thin films with predominantly (0001) interfaces by stacking the nanoflakes through spin coating. The influence of the annealing temperature and Sb content on the (0001) interface structure was systematically investigated at atomic scale using aberration-corrected scanning transmission electron microscopy. Annealing and Sb doping facilitate atom diffusion and migration between adjacent nanoflakes along the (0001) interface. As such it enhances interfacial connectivity and improves the electrical transport properties. Interfac reactions create new interfaces that increase the scattering and the Seebeck coefficient. Due to the simultaneous optimization of electrical conductivity and Seebeck coefficient, the maximum power factor of the Bi1.8Sb0.2Te3 nanoflake films reaches 1.72 mW m(-1) K-2, which is 43% higher than that of a pure Bi2Te3 thin film.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1002/EEM2.12755
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“Giant tunability of Rashba splitting at cation-exchanged polar oxide interfaces by selective orbital hybridization”. Xu H, Li H, Gauquelin N, Chen X, Wu W-F, Zhao Y, Si L, Tian D, Li L, Gan Y, Qi S, Li M, Hu F, Sun J, Jannis D, Yu P, Chen G, Zhong Z, Radovic M, Verbeeck J, Chen Y, Shen B, Advanced materials (2024). http://doi.org/10.1002/ADMA.202313297
Abstract: The 2D electron gas (2DEG) at oxide interfaces exhibits extraordinary properties, such as 2D superconductivity and ferromagnetism, coupled to strongly correlated electrons in narrow d-bands. In particular, 2DEGs in KTaO3 (KTO) with 5d t2g orbitals exhibit larger atomic spin-orbit coupling and crystal-facet-dependent superconductivity absent for 3d 2DEGs in SrTiO3 (STO). Herein, by tracing the interfacial chemistry, weak anti-localization magneto-transport behavior, and electronic structures of (001), (110), and (111) KTO 2DEGs, unambiguously cation exchange across KTO interfaces is discovered. Therefore, the origin of the 2DEGs at KTO-based interfaces is dramatically different from the electronic reconstruction observed at STO interfaces. More importantly, as the interface polarization grows with the higher order planes in the KTO case, the Rashba spin splitting becomes maximal for the superconducting (111) interfaces approximately twice that of the (001) interface. The larger Rashba spin splitting couples strongly to the asymmetric chiral texture of the orbital angular moment, and results mainly from the enhanced inter-orbital hopping of the t2g bands and more localized wave functions. This finding has profound implications for the search for topological superconductors, as well as the realization of efficient spin-charge interconversion for low-power spin-orbitronics based on (110) and (111) KTO interfaces. An unambiguous cation exchange is discovered across the interfaces of (001), (110), and (111) KTaO3 2D electron gases fabricated at room temperature. Remarkably, the (111) interfaces with the highest superconducting transition temperature also turn out to show the strongest electron-phonon interaction and the largest Rashba spin splitting. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 29.4
DOI: 10.1002/ADMA.202313297
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“Goodenough-Kanamori-Anderson high-temperature ferromagnetism in tetragonal transition-metal xenes”. Yorulmaz U, Šabani D, Sevik C, Milošević, MV, 2D materials 11, 035013 (2024). http://doi.org/10.1088/2053-1583/AD3E08
Abstract: Seminal Goodenough-Kanamori-Anderson (GKA) rules provide an inceptive understanding of the superexchange interaction of two magnetic metal ions bridged with an anion, and suggest fostered ferromagnetic interaction for orthogonal bridging bonds. However, there are no examples of two-dimensional (2D) materials with structure that optimizes the GKA arguments towards enhanced ferromagnetism and its critical temperature. Here we reveal that an ideally planar GKA ferromagnetism is indeed stable in selected tetragonal transition-metal xenes (tTMXs), with Curie temperature above 300 K found in CrC and MnC. We provide the general orbitally-resolved analysis of magnetic interactions that supports the claims and sheds light at the mechanisms dominating the magnetic exchange process in these structures. Furthermore, we propose the set of three GKA-like rules that will guarantee room temperature ferromagetnism. With recent advent of epitaxially-grown tetragonal 2D materials, our findings earmark tTMXs for facilitated spintronic and magnonic applications, or as a desirable magnetic constituent of functional 2D heterostructures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 5.5
DOI: 10.1088/2053-1583/AD3E08
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“Mitigated oxygen loss in lithium-rich manganese-based cathode enabled by strong Zr-O affinity”. Wang G, Xie C, Wang H, Li Q, Xia F, Zeng W, Peng H, Van Tendeloo G, Tan G, Tian J, Wu J, Advanced functional materials , 2313672 (2024). http://doi.org/10.1002/ADFM.202313672
Abstract: Oxygen loss is a serious problem of lithium-rich layered oxide (LLO) cathodes, as the high capacity of LLO relies on reversible oxygen redox. Oxygen release can occur at the surface leading to the formation of spinel or rock salt structures. Also, the lattice oxygen will usually become unstable after long cycling, which remains a major roadblock in the application of LLO. Here, it is shown that Zr doping is an effective strategy to retain lattice oxygen in LLO due to the high affinity between Zr and O. A simple sol-gel method is used to dope Zr4+ into the LLOs to adjust the local electronic structure and inhibit the diffusion of oxygen anions to the surface during cycling. Compared with untreated LLOs, LLO-Zr cathodes exhibit a higher cycling stability, with 94% capacity retention after 100 cycles at 0.4 C, up to 223 mAh g-1 at 1 C, and 88% capacity retention after 300 cycles. Theoretical calculations show that due to the strong Zr-O covalent bonding, the formation energy of oxygen vacancies has effectively increased and the loss of lattice oxygen under high voltage can be suppressed. This study provides a simple method for developing high-capacity and cyclability Li-rich cathode materials for lithium-ion batteries. Oxygen release can occur at the cathode surface leading to the formation of spinel or rock salt structures. Here, it is shown that Zr doping is an effective strategy to retain lattice oxygen in lithium-rich layered oxides (LLO) due to the high affinity between Zr and O. LLO-Zr exhibit higher cycling stability, with 88% capacity retention after 300 cycles at 1 C. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
DOI: 10.1002/ADFM.202313672
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“Photoluminescence of germanium-vacancy centers in nanocrystalline diamond films : implications for quantum sensing applications”. Joy RM, Pobedinskas P, Bourgeois E, Chakraborty T, Goerlitz J, Herrmann D, Noel C, Heupel J, Jannis D, Gauquelin N, D'Haen J, Verbeeck J, Popov C, Houssiau L, Becher C, Nesladek M, Haenen K, ACS applied nano materials 7, 3873 (2024). http://doi.org/10.1021/ACSANM.3C05491
Abstract: Point defects in diamond, promising candidates for nanoscale pressure- and temperature-sensing applications, are potentially scalable in polycrystalline diamond fabricated using the microwave plasma-enhanced chemical vapor deposition (MW PE CVD) technique. However, this approach introduces residual stress in the diamond films, leading to variations in the characteristic zero phonon line (ZPL) of the point defect in diamond. Here, we report the effect of residual stress on germanium-vacancy (GeV) centers in MW PE CVD nanocrystalline diamond (NCD) films fabricated using single crystal Ge as the substrate and solid dopant source. GeV ensemble formation indicated by the zero phonon line (ZPL) at similar to 602 nm is confirmed by room temperature (RT) photoluminescence (PL) measurements. PL mapping results show spatial nonuniformity in GeV formation along with other defects, including silicon-vacancy centers in the diamond films. The residual stress in NCD results in shifts in the PL peak positions. By estimating a stress shift coefficient of (2.9 +/- 0.9) nm/GPa, the GeV PL peak position in the NCD film is determined to be between 598.7 and 603.2 nm. A larger ground state splitting due to the strain on a GeV-incorporated NCD pillar at a low temperature (10 K) is also reported. We also report the observation of intense ZPLs at RT that in some cases could be related to low Ge concentration and the surrounding crystalline environment. In addition, we also observe thicker microcrystalline diamond (MCD) films delaminate from the Ge substrate due to film residual stress and graphitic phase at the diamond/Ge substrate interface (confirmed by electron energy loss spectroscopy). Using this approach, a free-standing color center incorporated MCD film with dimensions up to 1 x 1 cm(2) is fabricated. Qualitative analysis using time-of-flight secondary ion mass spectroscopy reveals the presence of impurities, including Ge and silicon, in the MCD film. Our experimental results will provide insights into the scalability of GeV fabrication using the MW PE CVD technique and effectively implement NCD-based nanoscale-sensing applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.9
DOI: 10.1021/ACSANM.3C05491
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“Reduction of magnetic interaction due to clustering in doped transition-metal dichalcogenides : a case study of Mn-, V-, and Fe-doped WSe₂”. Tiwari S, Van de Put M, Sorée B, Hinkle C, Vandenberghe WG, ACS applied materials and interfaces 16, 4991 (2024). http://doi.org/10.1021/ACSAMI.3C14114
Abstract: Using Hubbard-U-corrected density functional theory calculations, lattice Monte Carlo simulations, and spin Monte Carlo simulations, we investigate the impact of dopant clustering on the magnetic properties of WSe2 doped with period four transition metals. We use manganese (Mn) and iron (Fe) as candidate n-type dopants and vanadium (V) as the candidate p-type dopant, substituting the tungsten (W) atom in WSe2. Specifically, we determine the strength of the exchange interaction in Fe-, Mn-, and V-doped WSe2 in the presence of clustering. We show that the clusters of dopants are energetically more stable than discretely doped systems. Further, we show that in the presence of dopant clustering, the magnetic exchange interaction significantly reduces because the magnetic order in clustered WSe2 becomes more itinerant. Finally, we show that the clustering of the dopant atoms has a detrimental effect on the magnetic interaction, and to obtain an optimal Curie temperature, it is important to control the distribution of the dopant atoms.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 9.5
DOI: 10.1021/ACSAMI.3C14114
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“3D reconstruction of Ni4Ti3 precipitates in a Ni51Ti49 alloy in a FIB/SEM dual-beam system”. Cao S, Tirry W, van den Broek W, Schryvers D, Materials science forum 583, 277 (2008). http://doi.org/10.4028/www.scientific.net/MSF.583.277
Abstract: Ni4Ti3 precipitates play an important role in the shape memory and superelastic behaviour of thermo-mechanically treated Ni-Ti material. The 3D morphology and distribution of such precipitates with lenticular shape and rhombohedral atomic structure in the austenitic B2 matrix of a binary Ni-rich Ni-Ti alloy has been elucidated via a slice view procedure in a Dual-Beam FIB/SEM system. With the sequence of cross-section SE images obtained from the SEM, a 3D reconstruction has been achieved after proper alignment and image processing, from which both qualitative and quantitative analysis can be performed. Careful imaging is needed to ensure that all variants of the precipitates are observed with equal probability, regardless sample orientation. Moreover, due to the weak contrast of the precipitates, proper imaging conditions need to be selected to allow for semi-automated image treatment. Finally, a volume ratio of 10.2% for the Ni4Ti3 precipitates could be calculated, summed over all variants, which yields a net composition of Ni50.36Ti49.64 for the matrix, leading to an increase of 113 degrees for the martensitic start temperature Ms. Also, the expected relative orientation of the different variants of the precipitates could be confirmed. In the near future, other quantitative measures on the distribution of the precipitates can be expected.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
DOI: 10.4028/www.scientific.net/MSF.583.277
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“Ab initio approach to superexchange interactions in alkali doped fullerides AC60”. Nikolaev AV, Michel KH, AIP conference proceedings
T2 –, 18th International Winterschool/Euroconference on Electronic Properties, of Novel Materials, MAR 06-JUN 13, 2004, Kirchberg, AUSTRIA , 393 (2004). http://doi.org/10.1063/1.1812115
Abstract: The superexchange interactions between the fullerenes arise as a result of the electron transfer from the C-60 molecule to the alkali atom and back. We present a scheme, which is a configuration interaction approach based on the valence bond (Heitler-London) method. The effect of superexchange is described together with chemical bonding by constructing and solving a secular equation, rather than by using a perturbation treatment. We have considered 180degrees and 90degrees superexchange for the C-60 Cs-C-60 pathways. The calculations account for unusual electronic properties of polymer orthorhombic and quenched cubic phases of CsC60: two lines in nuclear magnetic resonance experiments, the development of a spin-singlet ground state and a decrease of magnetic susceptibility as T-->0.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
DOI: 10.1063/1.1812115
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“Atomic structure of alloys close to phase transitions”. Van Tendeloo G, Schryvers D, Nucleation and growth processes in materials 580, 283 (2000)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Characterisation of multilayer ramp-type REBa2Cu3O7-\delta structures by scanning probe microscopy and high-resolution electron microscopy”. Blank DHA, Rijnders AJHM, Verhoeven MAJ, Bergs RMH, Rogalla H, Verbist K, Lebedev O, Van Tendeloo G, Journal of alloys and compounds
T2 –, Symposium on High Temperature Superconductor Thin Films, Growth, Mechanisms, Interfaces, Multilayers, at the 1996 Spring Meeting of the European-Materials-Society, June 04-07, 1996, Strasbourg, France 251, 206 (1997). http://doi.org/10.1016/S0925-8388(96)02799-5
Abstract: We studied the morphology of ramps in REBa2CU3O7 (REBCO) epitaxial films on SrTiO3 substrates, fabricated by RF magnetron sputter deposition and pulsed laser deposition (PLD), by scanning probe microscopy (SPM) and high resolution electron microscopy (HREM). The ramps were fabricated by Ar ion beam etching using masks of standard photoresist and TIN. AFM-studies on ramps in sputter deposited films show a strong dependence, i.e. formation of facets and ridges, on the angle of incidence of the ion beam with respect to the substrate surface as well as the rotation angle with respect to the crystal axes of the substrate. Ramps in pulsed laser deposited films did not show this dependence, Furthermore, we studied the effect of an anneal step prior to the deposition of barrier layers (i.e. PrBa2CU3O7, SrTiO3, CeO2) on the ramp. First results show a recrystallization of the ramp surface, resulting in terraces and a non-homogeneous growth of the barrier material on top of it. The thickness variations, for thin layers of barrier material, con even become much larger than expected from the amount of deposited material and are dependent on the deposition and anneal conditions. HREM studies show a well defined interface between barrier layer and electrodes. The angle of the ramp depends on the etch rate of the mask and REBCO, and on the angle of incidence of the ion beam. TiN has a much lower etch rate compared to photoresist, resulting in an angle of the ramp comparable to the angle of incidence, resulting in a low etching rate on the ramp. These results will lead to improved electrical characteristics of ramp-type junctions.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.133
DOI: 10.1016/S0925-8388(96)02799-5
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