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Author | Sankaran, K.J.; Hoang, D.Q.; Kunuku, S.; Korneychuk, S.; Turner, S.; Pobedinskas, P.; Drijkoningen, S.; Van Bael, M.K.; D' Haen, J.; Verbeeck, J.; Leou, K.-C.; Lin, I.-N.; Haenen, K. | ||||
Title | Enhanced optoelectronic performances of vertically aligned hexagonal boron nitride nanowalls-nanocrystalline diamond heterostructures | Type | A1 Journal article | ||
Year | 2016 | Publication | Scientific reports | Abbreviated Journal | Sci Rep-Uk |
Volume | 6 | Issue | 6 | Pages | 29444 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | Field electron emission (FEE) properties of vertically aligned hexagonal boron nitride nanowalls (hBNNWs) grown on Si have been markedly enhanced through the use of nitrogen doped nanocrystalline diamond (nNCD) films as an interlayer. The FEE properties of hBNNWs-nNCD heterostructures show a low turn-on field of 15.2 V/mum, a high FEE current density of 1.48 mA/cm(2) and life-time up to a period of 248 min. These values are far superior to those for hBNNWs grown on Si substrates without the nNCD interlayer, which have a turn-on field of 46.6 V/mum with 0.21 mA/cm(2) FEE current density and life-time of 27 min. Cross-sectional TEM investigation reveals that the utilization of the diamond interlayer circumvented the formation of amorphous boron nitride prior to the growth of hexagonal boron nitride. Moreover, incorporation of carbon in hBNNWs improves the conductivity of hBNNWs. Such a unique combination of materials results in efficient electron transport crossing nNCD-to-hBNNWs interface and inside the hBNNWs that results in enhanced field emission of electrons. The prospective application of these materials is manifested by plasma illumination measurements with lower threshold voltage (370 V) and longer life-time, authorizing the role of hBNNWs-nNCD heterostructures in the enhancement of electron emission. | ||||
Address | IMOMEC, IMEC vzw, 3590 Diepenbeek, Belgium | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000379391000001 | Publication Date | 2016-07-12 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2045-2322 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 4.259 | Times cited | 15 | Open Access | |
Notes | The authors like to thank the financial support of the Research Foundation Flanders (FWO) via Research Project G.0456.12, G0044.13N and the Methusalem “NANO” network. Kamatchi Jothiramalingam Sankaran, Stuart Turner, and Paulius Pobedinskas are Postdoctoral Fellows of the Research Foundations Flanders (FWO). | Approved | Most recent IF: 4.259 | ||
Call Number | c:irua:134643 c:irua:134643UA @ admin @ c:irua:134643 | Serial | 4119 | ||
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Author | Turner, S.; Idrissi, H.; Sartori, A.F.; Korneychuck, S.; Lu, Y.-G.; Verbeeck, J.; Schreck, M.; Van Tendeloo, G. | ||||
Title | Direct imaging of boron segregation at dislocations in B:diamond heteroepitaxial films | Type | A1 Journal article | ||
Year | 2016 | Publication | Nanoscale | Abbreviated Journal | Nanoscale |
Volume | 8 | Issue | 8 | Pages | 2212-2218 |
Keywords | A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) | ||||
Abstract | A thin film of heavily B-doped diamond has been grown epitaxially by microwave plasma chemical vapor deposition on an undoped diamond layer, on top of a Ir/YSZ/Si(001) substrate stack, to study the boron segregation and boron environment at the dislocations present in the film. The density and nature of the dislocations were investigated by conventional and weak-beam dark-field transmission electron microscopy techniques, revealing the presence of two types of dislocations: edge and mixed-type 45 degrees dislocations. The presence and distribution of B in the sample was studied using annular dark-field scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy. Using these techniques, a segregation of B at the dislocations in the film is evidenced, which is shown to be intermittent along the dislocation. A single edge-type dislocation was selected to study the distribution of the boron surrounding the dislocation core. By imaging this defect at atomic resolution, the boron is revealed to segregate towards the tensile strain field surrounding the edge-type dislocations. An investigation of the fine structure of the B-K edge at the dislocation core shows that the boron is partially substitutionally incorporated into the diamond lattice and partially present in a lower coordination (sp(2)-like hybridization). | ||||
Address | EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. stuart.turner@uantwerpen.be | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000368860900053 | Publication Date | 2015-12-21 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2040-3364 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 7.367 | Times cited | 15 | Open Access | |
Notes | S. T. acknowledges the fund for scien tific research Flanders (FWO) for a post-doctoral scholarship and under contract number G.0044.13N | Approved | Most recent IF: 7.367 | ||
Call Number | c:irua:131597UA @ admin @ c:irua:131597 | Serial | 4121 | ||
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Author | Babynina, A.; Fedoruk, M.; Kuhler, P.; Meledin, A.; Doblinger, M.; Lohmueller, T. | ||||
Title | Bending Gold Nanorods with Light | Type | A1 Journal article | ||
Year | 2016 | Publication | Nano letters | Abbreviated Journal | Nano Lett |
Volume | 16 | Issue | 16 | Pages | 6485-6490 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | V-shaped gold nanoantennas are the functional components of plasmonic metasurfaces, which are capable of manipulating light in unprecedented ways. Designing a metasurface requires the custom arrangement of individual antennas with controlled shape and orientation. Here, we show how highly crystalline gold nanorods in solution can be bend, one-by one, into a V-shaped geometry and printed to the surface of a solid support through a combination of plasmonic heating and optical force. Significantly, we demonstrate that both the bending angle and the orientation of each rod-antenna can be adjusted independent from each other by tuning the laser intensity and polarization. This approach is applicable for the patterning of V-shaped plasmonic antennas on almost any substrate, which holds great potential for the fabrication of ultrathin optical components and devices. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000385469800072 | Publication Date | 2016-09-06 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1530-6984 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 12.712 | Times cited | 24 | Open Access | |
Notes | PMID:27598653 We would also like to thank Prof. Jochen Feldmann and Bernhard Bohn for fruitful discussions. | Approved | Most recent IF: 12.712 | ||
Call Number | c:irua:135172 | Serial | 4122 | ||
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Author | Kirilenko, D.A.; Brunkov, P.N. | ||||
Title | Measuring the height-to-height correlation function of corrugation in suspended graphene | Type | A1 Journal article | ||
Year | 2016 | Publication | Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
Volume | 165 | Issue | 165 | Pages | 1-7 |
Keywords | A1 Journal article; Electron Microscopy for Materials Science (EMAT); | ||||
Abstract | Nanocorrugation of 2D crystals is an important phenomenon since it affects their electronic and mechanical properties. The corrugation may have various sources; one of them is flexural phonons that, in particular, are responsible for the thermal conductivity of graphene. A study of corrugation of just the suspended graphene can reveal much of valuable information on the physics of this complicated phenomenon. At the same time, the suspended crystal nanorelief can hardly be measured directly because of high flexibility of the 2D crystal. Moreover, the relief portion related to rapid out-of-plane oscillations (flexural phonons) is also inaccessible by such measurements. Here we present a technique for measuring the Fourier components of the height-height correlation function H(q) of suspended graphene which includes the effect of flexural phonons. The technique is based on the analysis of electron diffraction patterns. The H(q) is measured in the range of wavevectors q approximately 0.4-4.5nm(-1). At the upper limit of this range H(q) does follow the T/kappaq(4) law. So, we measured the value of suspended graphene bending rigidity kappa=1.2+/-0.4eV at ambient temperature T approximately 300K. At intermediate wave vectors, H(q) follows a slightly weaker exponent than theoretically predicted q(-3.15) but is closer to the results of the molecular dynamics simulation. At low wave vectors, the dependence becomes even weaker, which may be a sign of influence of charge carriers on the dynamics of undulations longer than 10nm. The technique presented can be used for studying physics of flexural phonons in other 2D materials. | ||||
Address | Ioffe Institute, Politekhnicheskaya ul. 26, 194021 St-Petersburg, Russia; ITMO University, Kronverksky pr. 49, 197101 St. Petersburg, Russia | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000375946200001 | Publication Date | 2016-03-28 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0304-3991 | ISBN | Additional Links | ||
Impact Factor | 2.843 | Times cited | 3 | Open Access | |
Notes | D.K. thanks the RFBR (Grant no. 16-32-60165) for the partial support of this research. The work was carried out in part at the Joint Research Center “Material Science and Characterization in Advanced Technologies” (St-Petersburg, Russia) under the financial support from the Ministry of Education and Science of the Russian Federation (Agreement 14.621.21.0007, 04.12.2014, id RFMEFI62114X0007, the use of the Jeol JEM-2100F microscope) and at EMAT, Universiteit Antwerpen (Antwerpen, Belgium), (the use of the FEI Tecnai G2 microscope). | Approved | Most recent IF: 2.843 | ||
Call Number | EMAT @ emat @ | Serial | 4124 | ||
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Author | Gonnissen, J.; De Backer, A.; den Dekker, A.J.; Sijbers, J.; Van Aert, S. | ||||
Title | Detecting and locating light atoms from high-resolution STEM images: The quest for a single optimal design | Type | A1 Journal article | ||
Year | 2016 | Publication | Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
Volume | 170 | Issue | 170 | Pages | 128-138 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab | ||||
Abstract | In the present paper, the optimal detector design is investigated for both detecting and locating light atoms from high resolution scanning transmission electron microscopy (HR STEM) images. The principles of detection theory are used to quantify the probability of error for the detection of light atoms from HR STEM images. To determine the optimal experiment design for locating light atoms, use is made of the so-called Cramer-Rao Lower Bound (CRLB). It is investigated if a single optimal design can be found for both the detection and location problem of light atoms. Furthermore, the incoming electron dose is optimised for both research goals and it is shown that picometre range precision is feasible for the estimation of the atom positions when using an appropriate incoming electron dose under the optimal detector settings to detect light atoms. | ||||
Address | Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: sandra.vanaert@uantwerpen.be | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000386925500014 | Publication Date | 2016-07-26 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0304-3991 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 2.843 | Times cited | 6 | Open Access | |
Notes | The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G.0368.15, G.0369.15 and G.0374.13) and a postdoctoral research grant to A. De Backer. The research leading to these results has also received funding from the European Union Seventh Framework Programme [FP7/2007-2013] under Grant agreement no. 312483 (ESTEEM2). The authors would also like to thank A. Rosenauer for providing access to the STEMsim software and Gerardo T. Martinez for fruitful discussions.; esteem2_jra2 | Approved | Most recent IF: 2.843 | ||
Call Number | c:irua:135337 c:irua:135337 | Serial | 4128 | ||
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Author | Spadaro, M.C.; Luches, P.; Bertoni, G.; Grillo, V.; Turner, S.; Van Tendeloo, G.; Valeri, S.; D'Addato, S. | ||||
Title | Influence of defect distribution on the reducibility of CeO2-x nanoparticles | Type | A1 Journal article | ||
Year | 2016 | Publication | Nanotechnology | Abbreviated Journal | Nanotechnology |
Volume | 27 | Issue | 27 | Pages | 425705 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Ceria nanoparticles (NPs) are fundamental in heterogeneous catalysis because of their ability to store or release oxygen depending on the ambient conditions. Their oxygen storage capacity is strictly related to the exposed planes, crystallinity, density and distribution of defects. In this work a study of ceria NPs produced with a ligand-free, physical synthesis method is presented. The NP films were grown by a magnetron sputtering based gas aggregation source and studied by high resolution- and scanning-transmission electron microscopy and x-ray photoelectron spectroscopy. In particular, the influence of the oxidation procedure on the NP reducibility has been investigated. The different reducibility has been correlated to the exposed planes, crystallinity and density and distribution of structural defects. The results obtained in this work represent a basis to obtain cerium oxide NP with desired oxygen transport properties. | ||||
Address | Dipartimento FIM, Universita di Modena e Reggio Emilia, via G. Campi 213/a, I-41125 Modena, Italy. CNR-NANO, via G. Campi 213/a, I-41125 Modena, Italy | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000385483900004 | Publication Date | 2016-09-15 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0957-4484 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.44 | Times cited | 11 | Open Access | |
Notes | The authors gratefully acknowledge financial support by the Italian MIUR under grant FIRB RBAP115AYN (Oxides at the nanoscale: multifunctionality and applications). The activity is performed within the COST Action CM1104 'Reducible oxide chemistry, structure and functions'. The research leading to these results has received funding also from the European Union Seventh Framework Programme under Grant Agreement 312483—ESTEEM2 (Integrated Infrastructure Initiative–I3).; esteem2_ta | Approved | Most recent IF: 3.44 | ||
Call Number | EMAT @ emat @ c:irua:135424 | Serial | 4130 | ||
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Author | van der Stam, W.; Gradmann, S.; Altantzis, T.; Ke, X.; Baldus, M.; Bals, S.; de Mello Donega, C. | ||||
Title | Shape Control of Colloidal Cu2-x S Polyhedral Nanocrystals by Tuning the Nucleation Rates | Type | A1 Journal article | ||
Year | 2016 | Publication | Chemistry of materials | Abbreviated Journal | Chem Mater |
Volume | 28 | Issue | 28 | Pages | 6705-6715 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Synthesis protocols for colloidal nanocrystals (NCs) with narrow size and shape distributions are of particular interest for the successful implementation of these nanocrystals into devices. Moreover, the preparation of NCs with well-defined crystal phases is of key importance. In this work, we show that Sn(IV)-thiolate complexes formed in situ strongly influence the nucleation and growth rates of colloidal Cu2-x S polyhedral NCs, thereby dictating their final size, shape, and crystal structure. This allowed us to successfully synthesize hexagonal bifrustums and hexagonal bipyramid NCs with low-chalcocite crystal structure, and hexagonal nanoplatelets with various thicknesses and aspect ratios with the djurleite crystal structure, by solely varying the concentration of Sn(IV)-additives (namely, SnBr4) in the reaction medium. Solution and solid-state 119Sn NMR measurements show that SnBr4 is converted in situ to Sn(IV)-thiolate complexes, which increase the Cu2-x S nucleation barrier without affecting the precursor conversion rates. This influences both the nucleation and growth rates in a concentration-dependent fashion and leads to a better separation between nucleation and growth. Our approach of tuning the nucleation and growth rates with in situ-generated Sn-thiolate complexes might have a more general impact due to the availability of various metal-thiolate complexes, possibly resulting in polyhedral NCs of a wide variety of metal-sulfide compositions. | ||||
Address | Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University , P.O. Box 80000, 3508 TA Utrecht, The Netherlands | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000384399000037 | Publication Date | 2016-09-02 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0897-4756 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 9.466 | Times cited | 27 | Open Access | OpenAccess |
Notes | W.v.d.S. and C.d.M.D. acknowledge financial support from the division of Chemical Sciences (CW) of The Netherlands Organization for Scientific Research (NWO) under grant number ECHO.712.012.001. M.B. also gratefully acknowledges NWO for funding the NMR infrastructure (Middle Groot program, grant number 700.58.102). S.B. acknowledges financial support from the European Research Council (ERC Starting Grant # 335078-COLOURATOMS).; ECAS_Sara; (ROMEO:white; preprint:; postprint:restricted 12 months embargo; pdfversion:cannot); | Approved | Most recent IF: 9.466 | ||
Call Number | EMAT @ emat @ c:irua:135928 | Serial | 4285 | ||
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Author | Geuchies, J.J.; van Overbeek, C.; Evers, W.H.; Goris, B.; de Backer, A.; Gantapara, A.P.; Rabouw, F.T.; Hilhorst, J.; Peters, J.L.; Konovalov, O.; Petukhov, A.V.; Dijkstra, M.; Siebbeles, L.D.A.; van Aert, S.; Bals, S.; Vanmaekelbergh, D. | ||||
Title | In situ study of the formation mechanism of two-dimensional superlattices from PbSe nanocrystals | Type | A1 Journal article | ||
Year | 2016 | Publication | Nature materials | Abbreviated Journal | Nat Mater |
Volume | 15 | Issue | 15 | Pages | 1248-1254 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Oriented attachment of PbSe nanocubes can result in the formation of two-dimensional (2D) superstructures with long-range nanoscale and atomic order. This questions the applicability of classic models in which the superlattice grows by first forming a nucleus, followed by sequential irreversible attachment of nanocrystals, as one misaligned attachment would disrupt the 2D order beyond repair. Here, we demonstrate the formation mechanism of 2D PbSe superstructures with square geometry by using in situ grazing-incidence X-ray scattering (small angle and wide angle), ex situ electron microscopy, and Monte Carlo simulations. We observed nanocrystal adsorption at the liquid/gas interface, followed by the formation of a hexagonal nanocrystal monolayer. The hexagonal geometry transforms gradually through a pseudo-hexagonal phase into a phase with square order, driven by attractive interactions between the {100} planes perpendicular to the liquid substrate, which maximize facet-to-facet overlap. The nanocrystals then attach atomically via a necking process, resulting in 2D square superlattices. | ||||
Address | Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000389104400011 | Publication Date | 2016-09-05 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 1476-1122 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 39.737 | Times cited | 182 | Open Access | OpenAccess |
Notes | This research is part of the programme ‘Designing Dirac Carriers in semiconductor honeycomb superlattices (DDC13),’ which is supported by the Foundation for Fundamental Research on Matter (FOM), which is part of the Dutch Research Council (NWO). J.J.G. acknowledges funding from the Debye and ESRF Graduate Programs. The authors gratefully acknowledge funding from the Research Foundation Flanders (G.036915 G.037413 and funding of postdoctoral grants to B.G. and A.d.B). S.B. acknowledges the European Research Council, ERC grant No 335078—Colouratom. The authors gratefully acknowledge I. Swart and M. van Huis for fruitful discussions. We acknowledge funding from NWO-CW TOPPUNT ‘Superficial Superstructures’. The X-ray scattering measurements were performed at the ID10 beamline at ESRF under proposal numbers SC-4125 and SC-3786. The authors thank G. L. Destri and F. Zontone for their support during the experiments.; ECAS_Sara; (ROMEO:yellow; preprint:; postprint:restricted ; pdfversion:cannot); | Approved | Most recent IF: 39.737 | ||
Call Number | EMAT @ emat @ c:irua:136165 | Serial | 4289 | ||
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Author | Liu, Y.; Claes, N.; Trepka, B.; Bals, S.; Lang, P.R. | ||||
Title | A combined 3D and 2D light scattering study on aqueous colloidal model systems with tunable interactions | Type | A1 Journal article | ||
Year | 2016 | Publication | Soft matter | Abbreviated Journal | Soft Matter |
Volume | 12 | Issue | 12 | Pages | 8485-8494 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | In this article we report on the synthesis and characterization of a system of colloidal spheres suspended in an aqueous solvent which can be refractive index-matched, thus allowing for investigations of the particle near-wall dynamics by evanescent wave dynamic light scattering at concentrations up to the isotropic to ordered transition and beyond. The particles are synthesized by copolymerization of a fluorinated acrylic ester monomer with a polyethylene-glycol (PEG) oligomer by surfactant free emulsion polymerization. Static and dynamic light scattering experiments in combination with cryo transmission electron microscopy reveal that the particles have a core shell structure with a significant enrichment of the PEG chains on the particles surface. In index-matching DMSO/water suspensions the particles arrange in an ordered phase at volume fraction above 7%, if no additional electrolyte is present. The near-wall dynamics at low volume fraction are quantitatively described by the combination of electrostatic repulsion and hydrodynamic interaction between the particles and the wall. At volume fractions close to the isotropic to ordered transition, the near-wall dynamics are more complex and qualitatively reminiscent of the behaviour which was observed in hard sphere suspensions at high concentrations. | ||||
Address | Forschugszentrum Julich, Institute of Complex Systems ICS-3, Julich, Germany. p.lang@fz-juelich.de and Heinrich-Heine Universitat, Dusseldorf, Germany | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000386247100004 | Publication Date | 2016-08-22 |
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Series Volume | Series Issue | Edition | |||
ISSN | 1744-683X | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.889 | Times cited | 2 | Open Access | OpenAccess |
Notes | The authors thank Prof. J. K. G. Dhont and the ICS-3 group for useful discussions and support. YL would like to thank the Marie Sklodowska Curie Initial Training Network SOMATAI under the EU Grant Agreement No. 316866 for financial support. BT contributed to this work during an internship at Forschungszentrum Ju¨lich supported by the International Helmholtz Research School of Biophysics and Soft Matter (IHRS BioSoft), which is gratefully acknowledged. SB and NC acknowledge financial support from the European Research Council (ERC Starting Grant No. 335078-COLOURATOMS).; ECAS_Sara; (ROMEO:yellow; preprint:; postprint:restricted ; pdfversion:cannot); | Approved | Most recent IF: 3.889 | ||
Call Number | EMAT @ emat @ c:irua:136166 | Serial | 4292 | ||
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Author | Schouteden, K.; Govaerts, K.; Debehets, J.; Thupakula, U.; Chen, T.; Li, Z.; Netsou, A.; Song, F.; Lamoen, D.; Van Haesendonck, C.; Partoens, B.; Park, K. | ||||
Title | Annealing-Induced Bi Bilayer on Bi2Te3 Investigated via Quasi-Particle-Interference Mapping | Type | A1 Journal article | ||
Year | 2016 | Publication | ACS nano | Abbreviated Journal | Acs Nano |
Volume | 10 | Issue | 10 | Pages | 8778-8787 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) | ||||
Abstract | Topological insulators (TIs) are renowned for their exotic topological surface states (TSSs) that reside in the top atomic layers, and hence, detailed knowledge of the surface top atomic layers is of utmost importance. Here we present the remarkable morphology changes of Bi2Te3 surfaces, which have been freshly cleaved in air, upon subsequent systematic annealing in ultrahigh vacuum and the resulting effects on the local and area-averaging electronic properties of the surface states, which are investigated by combining scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and Auger electron spectroscopy (AES) experiments with density functional theory (DFT) calculations. Our findings demonstrate that the annealing induces the formation of a Bi bilayer atop the Bi2Te3 surface. The adlayer results in n-type doping, and the atomic defects act as scattering centers of the TSS electrons. We also investigated the annealing-induced Bi bilayer surface on Bi2Te3 via voltage-dependent quasi-particle-interference (QPI) mapping of the surface local density of states and via comparison with the calculated constant-energy contours and QPI patterns. We observed closed hexagonal patterns in the Fourier transform of real-space QPI maps with secondary outer spikes. DFT calculations attribute these complex QPI patterns to the appearance of a “second” cone due to the surface charge transfer between the Bi bilayer and the Bi2Te3. Annealing in ultrahigh vacuum offers a facile route for tuning of the topological properties and may yield similar results for other topological materials. | ||||
Address | Department of Physics, Virginia Tech , Blacksburg, Virginia 24061, United States | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000384399300073 | Publication Date | 2016-09-02 |
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Series Volume | Series Issue | Edition | |||
ISSN | 1936-0851 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 13.942 | Times cited | 15 | Open Access | |
Notes | The research in Leuven and Antwerp was supported by the Research FoundationFlanders (FWO, Belgium). The research in Leuven received additional support from the Flemish Concerted Research Action Program (BOF KULeuven, Project GOA/14/007) and the KULeuven Project GOA “Fundamental Challenges in Semiconductor Research”. Z.L. acknowledges the support from the China Scholarship Council (2011624021) and from KU Leuven Internal Funds (PDM). K.S. and J.D. acknowledge additional support from the FWO. T.C. and F.S. acknowledge the financial support of the National Key Projects for Basic Research of China (Grants 2013CB922103 and 2011CB922103), the National NaturalScience Foundation of China (Grant s 91421109, 11134005,11522432, and 11274003), the Natural Science Foundation ofJiangsu Province (Grant BK20130054), and the FundamentalResearch Funds for the Central Universities. K.P. wassupported by the U.S. National Science Foundation (DMR-1206354) and San Diego Supercomputer Center (SDSC)Comet and Gordon (DMR060009N). | Approved | Most recent IF: 13.942 | ||
Call Number | EMAT @ emat @ c:irua:136269 | Serial | 4294 | ||
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Author | Cassidy, S.J.; Batuk, M.; Batuk, D.; Hadermann, J.; Woodruff, D.N.; Thompson, A.L.; Clarke, S.J. | ||||
Title | Complex Microstructure and Magnetism in Polymorphic CaFeSeO | Type | A1 Journal article | ||
Year | 2016 | Publication | Inorganic chemistry | Abbreviated Journal | Inorg Chem |
Volume | 55 | Issue | 55 | Pages | 10714-10726 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | The structural complexity of the antiferromagnetic oxide selenide CaFeSeO is described. The compound contains puckered FeSeO layers composed of FeSe2O2 tetrahedra sharing all their vertexes. Two polymorphs coexist that can be derived from an archetype BaZnSO structure by cooperative tilting of the FeSe2O2 tetrahedra. The polymorphs differ in the relative arrangement of the puckered layers of vertex-linked FeSe2O2 tetrahedra. In a noncentrosymmetric Cmc21 polymorph (a = 3.89684(2) A, b = 13.22054(8) A, c = 5.93625(2) A) the layers are related by the C-centering translation, while in a centrosymmetric Pmcn polymorph, with a similar cell metric (a = 3.89557(6) A, b = 13.2237(6) A, c = 5.9363(3) A), the layers are related by inversion. The compound shows long-range antiferromagnetic order below a Neel temperature of 159(1) K with both polymorphs showing antiferromagnetic coupling via Fe-O-Fe linkages and ferromagnetic coupling via Fe-Se-Fe linkages within the FeSeO layers. The magnetic susceptibility also shows evidence for weak ferromagnetism which is modeled in the refinements of the magnetic structure as arising from an uncompensated spin canting in the noncentrosymmetric polymorph. There is also a spin glass component to the magnetism which likely arises from the disordered regions of the structure evident in the transmission electron microscopy. | ||||
Address | Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, United Kingdom | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000385785700085 | Publication Date | 2016-10-05 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0020-1669 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 4.857 | Times cited | 6 | Open Access | |
Notes | We acknowledge the financial support of the EPSRC (Grants EP/I017844/1 and EP/M020517/1), the Leverhulme Trust (RPG-2014-221), and the Diamond Light Source (studentship support for S. J. Cassidy). We thank the ESTEEM2 network for enabling the electron microscopy investigations and the ISIS facility and the Diamond Light Source Ltd. for the award of beam time. We thank Dr. P. Manuel for assistance on WISH, Dr. R. I. Smith for assistance on GEM and POLARIS, and Dr. C. Murray and Dr. A. Baker for assistance on I11. | Approved | Most recent IF: 4.857 | ||
Call Number | EMAT @ emat @ c:irua:136823 | Serial | 4312 | ||
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Author | Zhang, F.; Inokoshi, M.; Batuk, M.; Hadermann, J.; Naert, I.; Van Meerbeek, B.; Vleugels, J. | ||||
Title | Strength, toughness and aging stability of highly-translucent Y-TZP ceramics for dental restorations | Type | A1 Journal article | ||
Year | 2016 | Publication | Dental Materials | Abbreviated Journal | Dent Mater |
Volume | 32 | Issue | 32 | Pages | e327-e337 |
Keywords | A1 Journal article; Electron Microscopy for Materials Science (EMAT); | ||||
Abstract | OBJECTIVE: The aim was to evaluate the optical properties, mechanical properties and aging stability of yttria-stabilized zirconia with different compositions, highlighting the influence of the alumina addition, Y2O3 content and La2O3 doping on the translucency. METHODS: Five different Y-TZP zirconia powders (3 commercially available and 2 experimentally modified) were sintered under the same conditions and characterized by X-ray diffraction with Rietveld analysis and scanning electron microscopy (SEM). Translucency (n=6/group) was measured with a color meter, allowing to calculate the translucency parameter (TP) and the contrast ratio (CR). Mechanical properties were appraised with four-point bending strength (n=10), single edge V-notched beam (SEVNB) fracture toughness (n=8) and Vickers hardness (n=10). The aging stability was evaluated by measuring the tetragonal to monoclinic transformation (n=3) after accelerated hydrothermal aging in steam at 134 degrees C, and the transformation curves were fitted by the Mehl-Avrami-Johnson (MAJ) equation. Data were analyzed by one-way ANOVA, followed by Tukey's HSD test (alpha=0.05). RESULTS: Lowering the alumina content below 0.25wt.% avoided the formation of alumina particles and therefore increased the translucency of 3Y-TZP ceramics, but the hydrothermal aging stability was reduced. A higher yttria content (5mol%) introduced about 50% cubic zirconia phase and gave rise to the most translucent and aging-resistant Y-TZP ceramics, but the fracture toughness and strength were considerably sacrificed. 0.2mol% La2O3 doping of 3Y-TZP tailored the grain boundary chemistry and significantly improved the aging resistance and translucency. Although the translucency improvement by La2O3 doping was less effective than for introducing a substantial amount of cubic zirconia, this strategy was able to maintain the mechanical properties of typical 3Y-TZP ceramics. SIGNIFICANCE: Three different approaches were compared to improve the translucency of 3Y-TZP ceramics. | ||||
Address | KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, Belgium | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 000389516400003 | Publication Date | 2016-10-06 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0109-5641 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 4.07 | Times cited | Open Access | ||
Notes | The authors acknowledge the Research Fund of KU Leu- ven under project 0T/10/052 and the Fund for Scientific Research Flanders (FWO-Vlaanderen) under grant G.0431.10N. F. Zhang thanks the Research Fund of KU Leuven for her post- doctoral fellowship (PDM/15/153). We thank M. Peumans for the translucency measurements. | Approved | Most recent IF: 4.07 | ||
Call Number | EMAT @ emat @ c:irua:136821 | Serial | 4313 | ||
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Author | Yu, CP.; Vega Ibañez, F.; Béché, A.; Verbeeck, J. | ||||
Title | Quantum wavefront shaping with a 48-element programmable phase plate for electrons | Type | A1 Journal Article | ||
Year | 2023 | Publication | SciPost Physics | Abbreviated Journal | SciPost Phys. |
Volume | 15 | Issue | Pages | 223 | |
Keywords | A1 Journal Article; Electron Microscopy for Materials Science (EMAT) | ||||
Abstract | We present a 48-element programmable phase plate for coherent electron waves produced by a combination of photolithography and focused ion beam. This brings the highly successful concept of wavefront shaping from light optics into the realm of electron optics and provides an important new degree of freedom to prepare electron quantum states. The phase plate chip is mounted on an aperture rod placed in the C2 plane of a transmission electron microscope operating in the 100-300 kV range. The phase plate's behavior is characterized by a Gerchberg-Saxton algorithm, showing a phase sensitivity of 0.075 rad/mV at 300 kV, with a phase resolution of approximately 3x10e−3π. In addition, we provide a brief overview of possible use cases and support it with both simulated and experimental results. | ||||
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Corporate Author | Thesis | ||||
Publisher | SciPost | Place of Publication | Editor | ||
Language | English | Wos | 001116838500002 | Publication Date | 2023-12-04 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2542-4653 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 5.5 | Times cited | 1 | Open Access | |
Notes | This project is the result of a long-term effort involving many differ- ent sources of funding: JV acknowledges funding from an ERC proof of concept project DLV- 789598 ADAPTEM, as well as a University IOF proof of concept project towards launching the AdaptEM spin-off and the eBEAM project, supported by the European Union’s Horizon 2020 research and innovation program FETPROACT-EIC-07-2020: emerging paradigms and com- munities. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 823717 – ESTEEM3 and via The IMPRESS project from the HORIZON EUROPE framework program for research and innovation under grant agreement n. 101094299. FV, JV, and AB acknowledge funding from G042820N ‘Explor- ing adaptive optics in transmission electron microscopy.’ CPY acknowledges funding from a TOP-BOF project from the University of Antwerp. | Approved | Most recent IF: 5.5; 2023 IF: NA | ||
Call Number | EMAT @ emat @c:irua:202037 | Serial | 8984 | ||
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Author | Vandemeulebroucke, D.; Batuk, M.; Hajizadeh, A.; Wastiaux, M.; Roussel, P.; Hadermann, J. | ||||
Title | Incommensurate Modulations and Perovskite Growth in LaxSr2–xMnO4−δAffecting Solid Oxide Fuel Cell Conductivity | Type | A1 Journal Article | ||
Year | 2024 | Publication | Chemistry of Materials | Abbreviated Journal | Chem. Mater. |
Volume | Issue | Pages | |||
Keywords | A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; | ||||
Abstract | Ruddlesden-Popper La????Sr2−????MnO4−???? materials are interesting symmetric solid oxide fuel cell electrodes due to their good redox stability, mixed ionic and electronic conducting behavior and thermal expansion that matches well with common electrolytes. In reducing environments – as at a solid oxide fuel cell anode – the x = 0.5 member, i.e. La0.5Sr1.5MnO4−????, has a much higher total conductivity than compounds with a different La/Sr ratio, although all those compositions have the same K2NiF4-type I4/mmm structure. The origin for this conductivity difference is not yet known in literature. Now, a combination of in-situ and ex-situ 3D electron diffraction, high-resolution imaging, energy-dispersive X-ray analysis and electron energy-loss spectroscopy uncovered clear differences between x=0.25 and x=0.5 in the pristine structure, as well as in the transformations upon high-temperature reduction. In La0.5Sr1.5MnO4−????, Ruddlesden-Popper n=2 layer defects and an amorphous surface layer are present, but not in La0.25Sr1.75MnO4−????. After annealing at 700°C in 5% H2/Ar, La0.25Sr1.75MnO4−???? transforms to a tetragonal 2D incommensurately modulated structure with modulation vectors ⃗????1 = 0.2848(1) · (⃗????* +⃗????*) and ⃗????2 =0.2848(1) · (⃗????* – ⃗????*), whereas La0.5Sr1.5MnO4−???? only partially transforms to an orthorhombic 1D incommensurately modulated structure, with ⃗???? = 0.318(2) · ⃗????*. Perovskite domains grow at the crystal edge at 700°C in 5% H2 or vacuum, due to the higher La concentration on the surface compared to the bulk, which leads to a different thermodynamic equilibrium. Since it is known that a lower degree of oxygen vacancy ordering and a higher amount of perovskite blocks enhance oxygen mobility, those differences in defect structure and structural transformation upon reduction, might all contribute to the higher conductivity of La0.5Sr1.5MnO4−???? in solid oxide fuel cell anode conditions compared to other La/Sr ratios. |
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Wos | 001174840900001 | Publication Date | 2024-02-20 |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0897-4756 | ISBN | Additional Links | UA library record; WoS full record | |
Impact Factor | 8.6 | Times cited | Open Access | Not_Open_Access | |
Notes | Universiteit Antwerpen, BOF TOP 38689 ; Fonds Wetenschappelijk Onderzoek, I003218N ; European Commission NanED, 956099 ; | Approved | Most recent IF: 8.6; 2024 IF: 9.466 | ||
Call Number | EMAT @ emat @c:irua:204354 | Serial | 8997 | ||
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