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Morozov, V.A.; Posokhova, S.M.; Deyneko, D., V; Savina, A.A.; Morozov, A., V; Tyablikov, O.A.; Redkin, B.S.; Spassky, D.A.; Hadermann, J.; Lazoryak, B., I |
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Title |
Influence of annealing conditions on the structure and luminescence properties of KGd1-xEux(MoO4)2(0\leq x\leq1) |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
CrystEngComm |
Abbreviated Journal |
Crystengcomm |
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Volume |
21 |
Issue |
42 |
Pages |
6460-6471 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
This study describes the influence of annealing temperature on the structure and luminescence properties of KGd1-xEux(MoO4)(2) (0 <= x <= 1). Compounds with the general formula (A ', A '')(n)[(W, Mo)O-4](m) are investigated as luminescent materials for photonic applications such as phosphor-converted LEDs (light-emitting diodes). Herein, the KGd0.8Eu0.2(MoO4)(2) light-rose crystal was grown by the Czochralski technique. Moreover, three polymorphs of KGd1-xEux(MoO4)(2) were present in the 923-1223 K range of annealing temperatures under ambient pressure: a triclinic alpha-phase, a disproportionately modulated monoclinic beta-phase and an orthorhombic gamma-phase with a KY(MoO4)(2)-type structure. The different behaviors of KGd(MoO4)(2) and KEu(MoO4)(2) were revealed by DSC studies. The number and the character of phase transitions for KGd1-xEux(MoO4)(2) depended on the elemental composition. The formation of a continuous range of solid solutions with the triclinic alpha-KEu(MoO4)(2)-type structure and ordering of K+ and Eu3+/Gd3+ cations were observed only for alpha-KGd1-xEux(MoO4)(2) (0 <= x <= 1) prepared at 923 K. The structures of gamma-KGd1-xEux(MoO4)(2) (x = 0 and 0.2) were studied using electron diffraction and refined using the powder X-ray diffraction data. The luminescence properties of KGd1-xEux(MoO4)(2) prepared at different annealing temperatures were studied and related to their different structures. The maxima of the D-5(0) -> F-7(2) integral emission intensities were found under excitation at lambda(ex) = 300 nm and lambda(ex) = 395 nm for triclinic scheelite-type alpha-KGd0.6Eu0.4(MoO4)(2) and monoclinic scheelite-type beta-KGd0.4Eu0.6(MoO4)(2) prepared at 1173 K, respectively. The latter shows the brightest red light emission among the KGd1-xEux(MoO4)(2) phosphors. The maximum and integral emission intensity of beta-KGd0.4Eu0.6(MoO4)(2) in the D-5(0) -> F-7(2) transition region is similar to 20% higher than that of the commercially used red phosphor Gd2O2S:Eu3+. Thus, beta-KGd0.4Eu0.6(MoO4)(2) is very attractive for application as a near-UV convertible red-emitting phosphor for LEDs. |
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000493072200015 |
Publication Date |
2019-09-20 |
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Edition |
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ISSN |
1466-8033 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.474 |
Times cited |
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Open Access  |
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Notes |
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Approved |
Most recent IF: 3.474 |
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Call Number |
UA @ admin @ c:irua:164603 |
Serial |
6304 |
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Author |
Pourbabak, S. |
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Title |
Influence of nano and microstructural features and defects in finegrained NiTi on the thermal and mechanical reversibility of the martensitic transformation |
Type |
Doctoral thesis |
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Year |
2020 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
166 p. |
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Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:165919 |
Serial |
6305 |
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Author |
Du, K.; Zhang, M.; Dai, C.; Zhou, Z.N.; Xie, Y.W.; Ren, Z.H.; Tian, H.; Chen, L.Q.; Van Tendeloo, G.; Zhang, Z. |
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Title |
Manipulating topological transformations of polar structures through real-time observation of the dynamic polarization evolution |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Nature communications |
Abbreviated Journal |
Nat Commun |
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Volume |
10 |
Issue |
10 |
Pages |
4864 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Topological structures based on controllable ferroelectric or ferromagnetic domain configurations offer the opportunity to develop microelectronic devices such as high-density memories. Despite the increasing experimental and theoretical insights into various domain structures (such as polar spirals, polar wave, polar vortex) over the past decade, manipulating the topological transformations of polar structures and comprehensively understanding its underlying mechanism remains lacking. By conducting an in-situ non-contact bias technique, here we systematically investigate the real-time topological transformations of polar structures in PbTiO3/SrTiO3 multilayers at an atomic level. The procedure of vortex pair splitting and the transformation from polar vortex to polar wave and out-of-plane polarization are observed step by step. Furthermore, the redistribution of charge in various topological structures has been demonstrated under an external bias. This provides new insights for the symbiosis of polar and charge and offers an opportunity for a new generation of microelectronic devices. |
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000492835100002 |
Publication Date |
2019-10-25 |
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Edition |
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ISSN |
2041-1723 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
12.124 |
Times cited |
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Most recent IF: 12.124 |
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Call Number |
UA @ admin @ c:irua:164681 |
Serial |
6307 |
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Author |
Lumbeeck, G. |
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Title |
Mechanisms of nano-plasticity in as-deposited and hydrided nanocrystalline Pd and Ni thin films |
Type |
Doctoral thesis |
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Year |
2019 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
130 p. |
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Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:164918 |
Serial |
6309 |
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Author |
Sirotina, A.P.; Callaert, C.; Volykhov, A.A.; Frolov, A.S.; Sanchez-Barriga, J.; Knop-Gericke, A.; Hadermann, J.; Yashina, L.V. |
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Title |
Mechanistic studies of gas reactions with multicomponent solids : what can we learn by combining NAP XPS and atomic resolution STEM/EDX? |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
The journal of physical chemistry: C : nanomaterials and interfaces |
Abbreviated Journal |
J Phys Chem C |
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Volume |
123 |
Issue |
43 |
Pages |
26201-26210 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Rapid development of experimental techniques has enabled real time studies of solid gas reactions at the level reaching the atomic scale. In the present paper, we focus on a combination of atomic resolution STEM/EDX, which visualizes the reaction zone, and near ambient pressure (NAP) XPS, which collects information for a surface layer of variable thickness under reaction conditions. We compare the behavior of two affined topological insulators, Bi2Te3 and Sb2Te3. We used a simple reaction with molecular oxygen occurring at 298 K, which is of practical importance to avoid material degradation. Despite certain limitations, a combination of in situ XPS and ex situ cross-sectional STEM/EDX allowed us to obtain a self-consistent picture of the solid gas reaction mechanism for oxidation of Sb2Te3 and Bi2Te3 crystals, which includes component redistribution between the oxide and the subsurface layer and Te segregation with formation of a thin ordered layer at the interface. The process is multistep in case of both compounds. At the very beginning of the oxidation process the reactivity is determined by the energy benefit of the corresponding element oxygen bond formation. Further in the oxidation process, the behavior of these two compounds becomes similar and features component redistribution between the oxide and the subsurface layer. |
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Wos |
000493865700019 |
Publication Date |
2019-10-03 |
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ISSN |
1932-7447; 1932-7455 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.536 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 4.536 |
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Call Number |
UA @ admin @ c:irua:164664 |
Serial |
6310 |
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Author |
Leuthner, G.T.; Hummel, S.; Mangler, C.; Pennycook, T.J.; Susi, T.; Meyer, J.C.; Kotakoski, J. |
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Title |
Scanning transmission electron microscopy under controlled low-pressure atmospheres |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
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Volume |
203 |
Issue |
203 |
Pages |
76-81 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Transmission electron microscopy (TEM) is carried out in vacuum to minimize the interaction of the imaging electrons with gas molecules while passing through the microscope column. Nevertheless, in typical devices, the pressure remains at 10(-7) mbar or above, providing a large number of gas molecules for the electron beam to crack, which can lead to structural changes in the sample. Here, we describe experiments carried out in a modified scanning TEM (STEM) instrument, based on the Nion UltraSTEM 100. In this instrument, the base pressure at the sample is around 2 x 10(-10 )mbar, and can be varied up to 10(-6) mbar through introduction of gases directly into the objective area while maintaining atomic resolution imaging conditions. We show that air leaked into the microscope column during the experiment is efficient in cleaning graphene samples from contamination, but ineffective in damaging the pristine lattice. Our experiments also show that exposure to O(2 )and H2O lead to a similar result, oxygen providing an etching effect nearly twice as efficient as water, presumably due to the two 0 atoms per molecule. H(2 )and N-2 environments have no influence on etching. These results show that the residual gas environment in typical TEM instruments can have a large influence on the observations, and show that chemical etching of carbon-based structures can be effectively carried out with oxygen. |
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Wos |
000465021000010 |
Publication Date |
2019-02-04 |
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ISSN |
0304-3991 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.843 |
Times cited |
4 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.843 |
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Call Number |
UA @ admin @ c:irua:165937 |
Serial |
6321 |
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Author |
Pittarello, L.; Mckibbin, S.; Yamaguchi, A.; Ji, G.; Schryvers, D.; Debaille, V.; Claeys, P. |
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Title |
Two generations of exsolution lamellae in pyroxene from Asuka 09545 : Clues to the thermal evolution of silicates in mesosiderite |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
The American mineralogist |
Abbreviated Journal |
Am Mineral |
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Volume |
104 |
Issue |
11 |
Pages |
1663-1672 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Mesosiderite meteorites consist of a mixture of crustal basaltic or gabbroic material and metal. Their formation process is still debated due to their unexpected combination of crust and core materials, possibly derived from the same planetesimal parent body, and lacking an intervening mantle component. Mesosiderites have experienced an extremely slow cooling rate from ca. 550 degrees C, as recorded in the metal (0.25-0.5 degrees C/Ma). Here we present a detailed investigation of exsolution features in pyroxene from the Antarctic mesosiderite Asuka (A) 09545. Geothermobarometry calculations, lattice parameters, lamellae orientation, and the presence of clinoenstatite as the host were used in an attempt to constrain the evolution of pyroxene from 1150 to 570 degrees C and the formation of two generations of exsolution lamellae. After pigeonite crystallization at ca. 1150 degrees C, the first exsolution process generated the thick augite lamellae along (100) in the temperature interval 1000-900 degrees C. By further cooling, a second order of exsolution lamellae formed within augite along (001), consisting of monoclinic low-Ca pyroxene, equilibrated in the temperature range 900-800 degrees C. The last process, occurring in the 600-500 degrees C temperature range, was likely the inversion of high to low pigeonite in the host crystal, lacking evidence for nucleation of orthopyroxene. The formation of two generations of exsolution lamellae, as well as of likely metastable pigeonite, suggest non-equilibrium conditions. Cooling was sufficiently slow to allow the formation of the lamellae, their preservation, and the transition from high to low pigeonite. In addition, the preservation of such fine-grained lamellae limits long-lasting, impact reheating to a peak temperature lower than 570 degrees C. These features, including the presence of monoclinic low-Ca pyroxene as the host, are reported in only a few mesosiderites. This suggests a possibly different origin and thermal history from most mesosiderites and that the crystallography (i.e., space group) of low-Ca pyroxene could be used as parameter to distinguish mesosiderite populations based on their cooling history. |
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000494707400014 |
Publication Date |
2019-08-22 |
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ISSN |
0003-004x |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.021 |
Times cited |
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Open Access |
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Approved |
Most recent IF: 2.021 |
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Call Number |
UA @ admin @ c:irua:164645 |
Serial |
6331 |
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Author |
Hendrickx, M. |
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Title |
Study of the effect of cation substitution on the local structure and the properties of perovskites and Li-ion battery cathode materials |
Type |
Doctoral thesis |
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Year |
2020 |
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Abbreviated Journal |
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Volume |
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Pages |
208 p. |
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Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:173128 |
Serial |
6618 |
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Author |
Milagres de Oliveira, T. |
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Title |
Three-dimensional characterisation of nanomaterials : from model-like systems to real nanostructures |
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Doctoral thesis |
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Year |
2020 |
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Abbreviated Journal |
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230 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:170020 |
Serial |
6627 |
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Author |
Vanrompay, H. |
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Title |
Toward fast and dose efficient electron tomography |
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Doctoral thesis |
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Year |
2020 |
Publication |
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Abbreviated Journal |
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Volume |
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Pages |
207 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Call Number |
UA @ admin @ c:irua:169852 |
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6632 |
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Author |
Skorikov, A. |
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Title |
Fast approaches for investigating 3D elemental distribution in nanomaterials |
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Doctoral thesis |
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Year |
2021 |
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Pages |
143 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:178855 |
Serial |
6795 |
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Author |
Pedrazo Tardajos, A. |
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Title |
Advanced graphene supports for 3D in situ transmission electron microscopy |
Type |
Doctoral thesis |
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Year |
2021 |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
247 p. |
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Keywords |
Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Abstract |
Transmission electron microscopy (TEM) is an ideal tool to investigate nanomaterials. The information from TEM experiments allows us to link the structure and composition of nanomaterials to their intrinsic physical properties. However, despite the significant evolution of the TEM field during the last two decades, major progress is still possible through the development of optimal TEM techniques and supports. The results presented in this thesis focus on the optimization of sample supports and their application. Among the different options, graphene has previously been reported as useful sample support for electron microscopy due to its unparalleled properties, for example, it is the thinnest known support and provides a protective effect to the sample under investigation. Unfortunately, commercial graphene grids show poor quality, in terms of intactness and cleanness, inhibiting their wide application within the field. Therefore, this thesis focuses on the application of optimized graphene TEM grids, obtained by transferring high quality graphene using an advanced procedure. This improvement on the transfer has enabled the visualization of materials with low contrast and high sensitivity towards the electron beam, such as surface ligands capping gold nanoparticles or metal halide perovskites. Furthermore, the implemented protocol is not only of interest for conventional TEM grids but also a major benefit for in situ TEM studies, where the sample is investigated in real time under certain stimuli. Hence, the same graphene transfer technology can be also applied to advanced in situ MEMS holders dedicated for both heating and gas experiments, where the thickness and insulating nature of the silicon nitride (Si3N4) support may hamper some applications. By engineering periodic arrays of holes in their Si3N4 membrane by focused ion beam, onto which the graphene is transferred, it has been possible to get proof-of-concept 3D in situ investigations of heat-induced morphological and compositional transformations of complex nanosystems. As an example, it has enabled the investigation of the possible phase-transition of metal halide perovskites upon heating using 2D and 3D structural characterization. Moreover, it has allowed the study of in situ three-dimensional nanoparticle dynamics during gas phase catalysis as well as the first steps that would lead towards the design and creation of the first Graphene Gas Cell. Consequently, implementation of the advanced graphene transfer technology described in this thesis is envisaged to impact a broad range of future experiments. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:181143 |
Serial |
6836 |
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Author |
Du, K. |
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Title |
In situ TEM study on the manipulation of ferroelectrics |
Type |
Doctoral thesis |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
91 p. |
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Keywords |
Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
The strong correlated oxide systems attract a lot of attentions of scientists recently, the coexistence and interplay between various degrees of freedom, such as charge, spin and orbital, has been demonstrated to induce some fancy physical properties and phenomenon, including metal-insulator transition, high temperature superconductivity, colossal magnetoresistance. As a part of the strong correlated oxide systems, the ferroelectrics is abundant in both physical properties and application. First, if the electric dipole continuously rotating around a stable core then a topological structure is produced. If people could manipulate the topological structure and simultaneously observe the structure evolution, with external field applied on the topological structure, then it is very likely for such kind of ferroelectrics to be the next generation of storage, for it is reported to need low power input and produce high density of storage. In the other hand, in solids, charge polarity can one-to-one correspond to spin polarity phenomenologically, such as ferroelectricity and ferromagnetism, antiferroelectricity and antiferromagnetism, but ferrielectricity and ferrimagnetism kept telling a disparate story in microscopic level. The claimed “ferrielectrics” in existing research is equivalent to ferroelectric ones, thus the findings of such a real irreducible solids would complete the last piece of the ferroelectrics family. While solving the above two questions remain challengeable: the size of topological structure is small (typically below 10 nm), general characterization methods are insufficient for such high demand on space resolution, not to mention manipulating and observing its dynamic behavior at an atomic level. Here, employing the spherical aberration corrected electron microscope, we applied external field (heating and bias) on ferroelectrics. Combined with high-end characterization methods including the high-angle annular dark field (HAADF-STEM) image, Electron Energy Loss Spectroscopy (EELS) and integrated differential phase contrast (iDPC), the dynamic evolution of ferroelectrics are observed and analyzed. The main findings of this paper could be concluded as listed here: (1) PbTiO3(001)// SrTiO3(001) is grown on DyScO3 and SrRuO3 by pusled laser deposition, the atomical EDS mapping results reveal that the interface between PTO and STO is atomically sharp. Increasing the thickness of PTO from 1 uc to 21 uc, the topological structure wihtin PTO layer would transform from a/c domain to wave, vortex and finally flux closure domain. The geometric phase analysis results (GPA) reveal that above topological structures are corresponding to various strain. (2) Combined with in-situ biasing holder, the electric bias was applied on polar vortex, and it evolved from vortex (0 V) to polar wave (2 V) and finally polar down (5 V). EELS analysis was performed and we find that negative charge is gathered at vortex core, which turns the Ti4+ to Ti3+ there. The oxygen vacancy at negative polarization surface and the negative charge at the positive polarization surface realized the polarization screening of polar down domain. (3) Through the atomic inspection and analysis on lattice structure of BaFe2Se3, the near ladders within single unit are found to be different in degree of tetramerization, thus leading to a residual polarization along the a-axis. The further in-situ heating and biasing experiment was conducted on BaFe2Se3, and the strong and weak ladders are proved to be independent for their behavior under external field. This findings distinguishes ferrielectrics from ferroelectrics in solids. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:179310 |
Serial |
6842 |
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Author |
Prabhakara, V. |
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Title |
Strain measurement for semiconductor applications with Raman spectroscopy and Transmission electron microscopy |
Type |
Doctoral thesis |
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Year |
2021 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
149 p. |
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Keywords |
Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Scaling down the size of transistors has been a trend for several decades which has led to improved transistor performance, increased transistor density and hence the overall computation power of IC chips. The trend slowed in recent years due to reliability and power consumption issues at the nanoscale. Hence strain is introduced into transistor channels that has beneficial effects on improving the mobility of charge carriers, providing an alternative pathway for enhancing transistor performance. Therefore, monitoring strain is vital for the semiconductor industry. With the recent trend of decreasing device dimensions (FinFETS ~ 10-20nm) and strain modulation being used throughout, industry needs a reliable and fast method as quality control or defect characterisation. Such a universal strain measurement method does not exist, and one relies on a combination of quantitative in-line methods and complex off-line approaches. In this thesis, I investigated TEM and Raman spectroscopy-based methodologies for strain measurement. In terms of TEM methodologies, advancements are made for the STEM moiré imaging, targeting strain spatial resolution enhancement. I introduce advanced quadrature demodulation and phase stepping interferometry applied to STEM moiré that greatly enhances the spatial resolution while providing enhanced field of view and sensitivity for strain measurement. We introduce ways to reduce scan distortions in strain maps using an alternative scan strategy called “Block scanning” and the non-linear regression applied for strain extraction. Prospects for 3D strain analysis using high-resolution tomography is also investigated which gives direct access for the full second order strain tensors calculation. Finally, we compare strain measurements from TEM techniques with inline techniques like Raman spectroscopy. Raman stress measurement involves sensitive identification of the TO and LO phonon peaks. Raman spectrum of strained Ge transistor channel consists of strongly overlapping peaks within the spectral resolution of the spectrometer. Hence, the process of deconvolution of the two peaks is rather challenging. Hence, we explore new polarisation geometries like radially polarised incoming light which was shown to ease the deconvolution problem resulting in improved precision for Raman stress–strain measurements. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:182261 |
Serial |
6847 |
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Author |
Zhang, Z.; Bourgeois, L.; Zhang, Y.; Rosalie, J.M.; Medhekar, N. |
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Title |
Advanced imaging and simulations of precipitate interfaces in aluminium alloys and their role in phase transformations |
Type |
P1 Proceeding |
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Year |
2020 |
Publication |
MATEC web of conferences
T2 – 17th International Conference on Aluminium Alloys (ICAA), October 26-29, 2020 |
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Pages |
09003 |
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Keywords |
P1 Proceeding; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Precipitation is accompanied by the formation and migration of heterophase interfaces. Using the combined approach of advanced imaging and atomistic simulations, we studied the precipitate-matrix interfaces in various aluminium alloy systems, aiming to resolve their detailed atomic structures and illuminate their role in phase transformations. |
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000652552200053 |
Publication Date |
2020-11-05 |
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Series Volume |
326 |
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ISSN |
2261-236x; 2274-7214 |
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UA library record; WoS full record |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:179147 |
Serial |
6851 |
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Author |
Velazco Torrejón, A. |
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Title |
Alternative scan strategies for high resolution STEM imaging |
Type |
Doctoral thesis |
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Year |
2021 |
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Pages |
131 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Currently, a large variety of materials are studied by transmission electron microscopy (TEM) as it offers the possibility to perform structural and elemental analysis at a local scale. Relatively recent advances in aberration correctors and electron sources allow the instrument to achieve atomic resolution. Along with these advances, a state-of-the-art technology has been reached in TEM. However, the instrument is far from being perfect and imperfections or external sources can make the interpretation of information troublesome. Environmental factors such as acoustic and mechanical vibrations, temperature fluctuations, etc., can induce sample drift and create image distortions. These distortions are enhanced in scanning operation because of the serial acquisition of the information, which are more apparent at atomic resolution as small field of views are imaged. In addition, scanning distortions are induced due to the finite time response of the scan coils. These types of distortions would reduce precision in atomic-scale strain analysis, for instance, in semiconductors. Most of the efforts to correct these distortions are focused on data processing techniques post-acquisition. Another limitation in TEM is beam damage effects. Beam damage arises because of the energy transferred to the sample in electron-sample interactions. In scanning TEM, at atomic resolution, the increased electron charge density (electron dose) carried on a sub-Å size electron probe may aggravate beam damage effects. Soft materials such as zeolites, organic, biological materials, etc., can be destroyed under irradiation limiting the amount of information that can be acquired. Current efforts to circumvent beam damage are mostly based on low electron dose acquisitions and data processing methods to maximize the signal at low dose conditions. In this thesis, a different approach is given to address drift and scanning distortions, as well as beam damage effects. Novel scan strategies are proposed for that purpose, which are shown to substantially overcome these issues compared to the standard scan method in TEM. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:180973 |
Serial |
6852 |
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Author |
Mahadi, A.H.; Ye, L.; Fairclough, S.M.; Qu, J.; Wu, S.; Chen, W.; Papaioannou, E.; Ray, B.; Pennycook, T.J.; Haigh, S.J.; Young, N.P.; Tedsree, K.; Metcalfe, I.S.; Tsang, S.C.E. |
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Title |
Beyond surface redox and oxygen mobility at pd-polar ceria (100) interface : underlying principle for strong metal-support interactions in green catalysis |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Applied Catalysis B-Environmental |
Abbreviated Journal |
Appl Catal B-Environ |
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270 |
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Pages |
118843 |
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A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
When ceria is used as a support for many redox catalysis involved in green catalysis, it is well-known that the overlying noble metal can gain access to a significant quantity of oxygen atoms with high mobility and fast reduction and oxidation properties under mild conditions. However, it is as yet unclear what the underlying principle and the nature of the ceria surface involved are. By using two tailored morphologies of ceria nanocrystals, namely cubes and rods, it is demonstrated from Scanning Transmission Electron Microscopy with Electron Energy Loss Spectroscopy (STEM-EELS) mapping and Pulse Isotopic Exchange (PIE) that ceria nano-cubes terminated with a polar surface (100) can give access to more than the top most layer of surface oxygen atoms. Also, they give higher oxygen mobility than ceria nanorods with a non-polar facet of (110). A new insight for the possible additional role of polar ceria surface plays in the oxygen mobility is obtained from Density Functional Theory (DFT) calculations which suggest that the (100) surface sites that has more than half-filled O on same plane can drive oxygen atoms to oxidise adsorbate(s) on Pd due to the strong electrostatic repulsion. |
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000526110500007 |
Publication Date |
2020-03-04 |
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0926-3373 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
22.1 |
Times cited |
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Most recent IF: 22.1; 2020 IF: 9.446 |
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Call Number |
UA @ admin @ c:irua:183959 |
Serial |
6856 |
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Vervaet, B.A.; Nast, C.C.; Jayasumana, C.; Schreurs, G.; Roels, F.; Herath, C.; Kojc, N.; Samaee, V.; Rodrigo, S.; Gowrishankar, R. |
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Title |
Chronic interstitial nephritis in agricultural communities : a toxin-induced proximal tubular nephropathy |
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A1 Journal article |
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Year |
2020 |
Publication |
European Medical Journal : Nephrology |
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8 |
Issue |
1 |
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40-42 |
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A1 Journal article; Electron microscopy for materials research (EMAT); Pathophysiology |
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2053-4248 |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:180862 |
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6858 |
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Author |
Roegiers, J. |
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Title |
Development of combined photocatalytic and active carbon fiber technology for indoor air purification based on Multiphysics models |
Type |
Doctoral thesis |
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Year |
2021 |
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Pages |
XXX, 197 p. |
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Doctoral thesis; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL) |
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Exposure to volatile organic compounds (VOCs) remains a major public health concern. Indoor VOC concentrations typically far exceed outdoor levels due to a variety of emission sources and the stringent insulation measures that are imposed today. Many attempts have been made to use photocatalysis for indoor air purification. In an ideal situation, photocatalysis is capable of complete mineralization of VOCs to H2O and CO2, without any byproduct formation. Moreover, the process can take place at standard atmospheric conditions, i.e. ambient temperature and atmospheric pressure. However, successful exploitation is still impeded due to low conversion efficiency, significant pressure loss (and hence a high energy consumption) and byproduct formation. In the first part of this thesis an attempt was made to tackles these problems by designing a novel type of photocatalytic (PCO) reactor. The PCO device consists of a cylindrical vessel filled with TiO2-coated glass tubes and equipped with UV fluorescence lamps. It was investigated in terms of fluid dynamics, coating properties, UV-light distribution and photocatalytic activity. Experimental data was later used to develop and calibrate a Multiphysics model. The model proved to be a useful tool for designing and upscaling the PCO reactor. Consequently, an optimized prototype reactor was constructed and tested according the CEN-EN-16846-1 standard for VOC removal. Although the prototype showed promising results for lab-scale conditions, it struggled with byproduct formation when purifying ppb-level VOCs. In the second part of this thesis, activated carbon adsorption was investigated in order to combine it with photocatalysis. Activated carbon fiber was opted for its fast kinetics, high adsorption capacity and thermo-electrical regeneration. The filter was studied in detail regarding the adsorption of polar and apolar VOCs at indoor air concentration levels and regeneration capabilities. Experimental data was used to develop a Multiphysics model for activated carbon adsorption as well. Consequently, a novel type of ACF filter was developed using the Multiphysics model, which was equipped with electrodes in the tips of the pleats for effective thermal regeneration. In the last part, the combination of both ACF and PCO was studied using a realistic case study. Based on the Multiphysics model, the feasibility of a so-called hybrid air purification device could be investigated. The Multiphysics model shows promising results for this hybrid PCO-ACF system and hence, a demo setup was constructed for future research. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:181137 |
Serial |
6860 |
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Haug, C.; Ruebeling, F.; Kashiwar, A.; Gumbsch, P.; Kübel, C.; Greiner, C. |
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Title |
Early deformation mechanisms in the shear affected region underneath a copper sliding contact |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Nature Communications |
Abbreviated Journal |
Nat Commun |
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11 |
Issue |
1 |
Pages |
839-8 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Dislocation mediated plastic deformation decisively influences the friction coefficient and the microstructural changes at many metal sliding interfaces during tribological loading. This work explores the initiation of a tribologically induced microstructure in the vicinity of a copper twin boundary. Two distinct horizontal dislocation traces lines (DTL) are observed in their interaction with the twin boundary beneath the sliding interface. DTL formation seems unaffected by the presence of the twin boundary but the twin boundary acts as an indicator of the occurring deformation mechanisms. Three concurrent elementary processes can be identified: simple shear of the subsurface area in sliding direction, localized shear at the primary DTL and crystal rotation in the layers above and between the DTLs around axes parallel to the transverse direction. Crystal orientation analysis demonstrates a strong compatibility of these proposed processes. Quantitatively separating these different deformation mechanisms is crucial for future predictive modeling of tribological contacts. |
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Publication Date |
2020-02-11 |
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Edition |
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ISSN |
2041-1723 |
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Additional Links |
UA library record |
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Impact Factor |
16.6 |
Times cited |
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Approved |
Most recent IF: 16.6; 2020 IF: 12.124 |
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Call Number |
UA @ admin @ c:irua:183619 |
Serial |
6863 |
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Guzzinati, G.; Ghielens, W.; Mahr, C.; Béché, A.; Rosenauer, A.; Calders, T.; Verbeeck, J. |
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Electron Bessel beam diffraction patterns, line scan of Si/SiGe multilayer |
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Dataset |
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2019 |
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Dataset; ADReM Data Lab (ADReM); Electron microscopy for materials research (EMAT) |
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no |
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UA @ admin @ c:irua:169114 |
Serial |
6865 |
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Guzzinati, G.; Das, P.P.; Zompra, A., A.; Nicopoulos, S.; Verbeeck, J. |
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Electron energy loss spectra of several organic compounds |
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Dataset |
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2020 |
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Dataset; Electron microscopy for materials research (EMAT) |
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Abstract |
We placed crystals of different compounds to explore the possibility of fingerprinting them through EELS. Here are representative datasets of 7 different compounds: b-cyclodextrin hexacarboxy cyclohexane tannin TH-15 peptide TH-27 peptide two different forms of piroxicam The datasets were collected at EMAT, using a monochromated FEI Titan3 TEM, within the scope of an EUSMI request. More information as well as analysis methodologies adopted for the data are detailed in the paper: Das et al. “Reliable Characterization of Organic & Pharmaceutical Compounds with High Resolution Monochromated EEL Spectroscopy”, Polymers 2020, 12(7), 1434. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:180654 |
Serial |
6866 |
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Author |
De wael, A. |
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Title |
Model-based quantitative scanning transmission electron microscopy for measuring dynamic structural changes at the atomic scale |
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Doctoral thesis |
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Year |
2021 |
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Pages |
xiv, 146 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Abstract |
Nanomaterialen kunnen uiterst interessante eigenschappen vertonen voor een verscheidenheid aan veelbelovende toepassingen, gaande van zonnecrème tot batterijen voor elektrische auto’s. Een nanometer is een miljard keer kleiner dan een meter. Op deze schaal kunnen de materiaaleigenschappen volledig verschillen van bulkmaterialen op grotere schaal. Bovendien hangen de eigenschappen van nanomaterialen sterk af van hun exacte grootte en vorm. Kleine verschillen in de posities van de atomen, in de grootte-orde van een picometer (nog eens duizend maal kleiner dan een nanometer), kunnen de fysische eigenschappen al drastisch beïnvloeden. Daarom is een betrouwbare kwantificering van de atomaire structuur van kritisch belang om de evolutie naar materiaalontwerp mogelijk te maken en inzicht te verwerven in de relatie tussen de fysische eigenschappen en de structuur van nanomaterialen. Daarnaast kan de atomaire structuur van nanomaterialen ook veranderen in de loop van de tijd ten gevolge van verschillende fysische processen. Het onderzoek dat in deze thesis gepresenteerd wordt, maakt het mogelijk om de dynamische structuurveranderingen van nanomaterialen betrouwbaar te kwantificeren op atomaire schaal door gebruik te maken van raster transmissie elektronenmicroscopie (STEM). Ik heb dit gerealiseerd door methodes te ontwikkelen waarmee ik het aantal atomen “achter elkaar” kan tellen in elke atoomkolom van een nanomateriaal, en dit op basis van beelden opgenomen met een elektronenmicroscoop. Een belangrijk verschil met telmethodes voor de analyse van een enkel beeld is het schatten van de kans dat een atoomkolom atomen zal verliezen of bijkrijgen van het ene naar het andere beeld in de tijdreeks. Deze kwantitatieve methode kan het ontrafelen van de tijdsafhankelijke structuur-eigenschappen relatie van een nanomateriaal mogelijk maken, wat uiteindelijk kan leiden tot efficiënter design en productie van nanomaterialen voor innovatieve toepassingen. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:179514 |
Serial |
6870 |
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Author |
Gorji, S.; Kashiwar, A.; Mantha, L.S.; Kruk, R.; Witte, R.; Marek, P.; Hahn, H.; Kübel, C.; Scherer, T. |
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Title |
Nanowire facilitated transfer of sensitive TEM samples in a FIB |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
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Volume |
219 |
Issue |
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Pages |
113075 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
We introduce a facile approach to transfer thin films and other mechanically sensitive TEM samples inside a FIB with minimal introduction of stress and bending. The method is making use of a pre-synthetized flexible freestanding Ag nanowire attached to the tip of a typical tungsten micromanipulator inside the FIB. The main advantages of this approach are the significantly reduced stress-induced bending during transfer and attachment of the TEM sample, the very short time required to attach and cut the nanowire, the operation at very low dose and ion current, and only using the e-beam for Pt deposition during the transfer of sensitive TEM samples. This results in a reduced sample preparation time and reduced exposure to the ion beam or e-beam for Pt deposition during the sample preparation and thus also reduced contamination and beam damage. The method was applied to a number of thin films and different TEM samples in order to illustrate the advantageous benefits of the concept. In particular, the technique has been successfully tested for the transfer of a thin film onto a MEMS heating chip for in situ TEM experiments. |
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2020-07-15 |
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ISSN |
0304-3991 |
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UA library record |
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Impact Factor |
2.2 |
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Approved |
Most recent IF: 2.2; 2020 IF: 2.843 |
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Call Number |
UA @ admin @ c:irua:183618 |
Serial |
6871 |
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Author |
Jannis, D. |
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Title |
Novel detection schemes for transmission electron microscopy |
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Doctoral thesis |
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Year |
2021 |
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Abbreviated Journal |
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Pages |
iv, 208 p. |
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Doctoral thesis; Electron microscopy for materials research (EMAT) |
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Abstract |
Electron microscopy is an excellent tool which provides resolution down to the atomic scale with up to pm precision in locating atoms. The characterization of materials in these length scales is of utmost importance to answer questions in biology, chemistry and material science. The successful implementation of aberration-corrected microscopes made atomic resolution imaging relatively easy, this could give the impression that the development of novel electron microscopy techniques would stagnate and only the application of these instruments as giant magnifying tools would continue. This is of course not true and a multitude of problems still exist in electron microscopy. Two of such issues are discussed below. One of the biggest problems in electron microscopy is the presence of beam damage which occurs due the fact that the highly energetic incoming electrons have sufficient kinetic energy to change the structure of the material. The amount of damage induced depends on the dose, hence minimizing this dose during an experiment is beneficial. This minimizing of the total dose comes at the expense of more noise due to the counting nature of the electrons. For this reason, the implementation of four dimensional scanning transmission electron microscopy (4D STEM) experiments has reduced the total dose needed per acquisition. However, the current cameras used to measure the diffraction patterns are still two orders of magnitude slower than to the conventional STEM methods. Improving the acquisition speed would make the 4D STEM technique more feasible and is of utmost importance for the beam sensitive materials since less dose is used during the acquisition. In TEM there is not only the possibility to perform imaging experiments but also spectroscopic measurements. There are two frequently used methods: electron energy-loss spectroscopy (EELS) and energy dispersive x-ray spectroscopy (EDX). EELS measures the energy-loss spectrum of the incoming electron which gives information on the available excitations in the material providing elemental sensitivity. In EDX, the characteristic x-rays, arising from the decay of an atom which is initially excited due to the incoming electrons, are detected providing similar elemental analysis. Both methods are able to provide comparable elemental information where in certain circumstances one outperforms the other. However, both methods have a detection limit of approximately 100-1000 ppm which is not sufficient for some materials. In this thesis, two novel techniques which can make significant progress for the two problems discussed above. |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:182404 |
Serial |
6872 |
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Marteleur, M.; Idrissi, H.; Amin-Ahmadi, B.; Prima, F.; Schryvers, D.; Jacques, P.J. |
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On the nucleation mechanism of {112} < 111 > mechanical twins in as-quenched beta metastable Ti-12 wt.% Mo alloy |
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A1 Journal article |
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Year |
2019 |
Publication |
Materialia |
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Volume |
7 |
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Pages |
Unsp 100418 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Recently developed beta-metastable Ti grades take advantage of the simultaneous activation of TRIP and TWIP effects for enhancing their work hardening rate. However, the role of each plasticity mechanism on the macroscopic mechanical response is still unclear. In this work, the nucleation mechanism of the first activated plasticity mechanism, namely {112} < 111 > twinning, was investigated. Firstly, post-mortem TEM analysis showed that twins nucleate on pre-existing microstructural defects such as thermal jogs with the zonal dislocation mechanism. The precipitation of the omega phase on twin boundaries has been observed, as well as the emission of numerous dislocations from super-jogs present in these twin boundaries. It is also shown that {112} < 111 > twins act as effective dislocation sources for the subsequent plasticity mechanisms such as beta -> alpha '' martensitic transformation and {332} < 111 > twinning. Secondly, in situ TEM tensile testing of the investigated Ti grade highlighted the primary role of the initial defect configuration present in the microstructure. It is shown that twins cannot nucleate without the presence of specific defects allowing the triggering of the dislocation decomposition needed for the twinning mechanism highlighted in investigated bulk samples. |
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000537131000052 |
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2019-07-31 |
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2589-1529 |
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UA library record; WoS full record; WoS citing articles |
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UA @ admin @ c:irua:170326 |
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6875 |
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Samaeeaghmiyoni, V.; Cordier, P.; Demouchy, S.; Bollinger, C.; Gasc, J.; Mussi, A.; Schryvers, D.; Idrissi, H. |
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Title |
Research data supporting for Stress-induced amorphization triggers deformation in the lithospheric mantle |
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2020 |
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Dataset; Electron microscopy for materials research (EMAT) |
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Most recent IF: NA |
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UA @ admin @ c:irua:180668 |
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6881 |
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Author |
Guzzinati, G.; Béché, A.; McGrouther, D.; Verbeeck, J. |
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Title |
Rotation of electron beams in the presence of localised, longitudinal magnetic fields |
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2019 |
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Dataset; Electron microscopy for materials research (EMAT) |
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Electron Bessel beams have been generated by inserting an annular aperture in the illumination system of a TEM. These beams have passed through a localised magnetic field. As a result a low amount of image rotation (which is expected to be proportional to the longitudinal component of the magnetic field) is observed in the far field. A measure of this rotation should give access to the magneti field. The two datasets have been acquired in a FEI Titan3 microscope, operated at 300kV. The file focalseries.tif contains a series of images acquired varying the magnetic field through the objective lens. The file lineprofile.ser contains a series of images acquired by scanning the beam over a sample with several magnetised nanopillars. For reference, check the associated publication. |
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no |
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Call Number |
UA @ admin @ c:irua:169135 |
Serial |
6883 |
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Author |
Jannis, D.; Müller-Caspary, K.; Béché, A.; Oelsner, A.; Verbeeck, J. |
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Title |
Spectrocopic coincidence experiment in transmission electron microscopy |
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Dataset |
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2019 |
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Dataset; Electron microscopy for materials research (EMAT) |
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This dataset contains individual EEL and EDX events where for every event (electron or X-ray), their energy and time of arrival is stored. The experiment was performed in a transmission electron microscope (Tecnai Osiris) at 200 keV. The material investigated is an Al-Mg-Si-Cu alloy. The 'full_dataset.mat' contains the full dataset and the 'subset.mat' has the first five frames of the full dataset. The attached 'EELS-EDX.ipynb' is a jupyter notebook file. This file describes the data processing in order to observe the temporal correlation between the electrons and X-rays. |
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no |
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Call Number |
UA @ admin @ c:irua:169112 |
Serial |
6888 |
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Bouwmeester, R.L.; de Hond, K.; Gauquelin, N.; Verbeeck, J.; Koster, G.; Brinkman, A. |
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Title |
Stabilization of the perovskite phase in the Y-Bi-O system by using a BaBiO₃ buffer layer |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
Physica status solidi: rapid research letters |
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13 |
Issue |
7 |
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1800679 |
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A1 Journal article; Electron microscopy for materials research (EMAT) |
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A topological insulating phase has theoretically been predicted for the thermodynamically unstable perovskite phase of YBiO3. Here, it is shown that the crystal structure of the Y-Bi-O system can be controlled by using a BaBiO3 buffer layer. The BaBiO3 film overcomes the large lattice mismatch of 12% with the SrTiO3 substrate by forming a rocksalt structure in between the two perovskite structures. Depositing an YBiO3 film directly on a SrTiO3 substrate gives a fluorite structure. However, when the Y-Bi-O system is deposited on top of the buffer layer with the correct crystal phase and comparable lattice constant, a single oriented perovskite structure with the expected lattice constants is observed. |
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000477671800005 |
Publication Date |
2019-03-06 |
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1862-6254 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
11 |
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Notes |
The work at the University of Twente is financially supported by NWO through a VICI grant. N.G. and J.V. acknowledge financial support from the GOA project “Solarpaint” of the University of Antwerp. The microscope used for this experiment has been partially financed by the Hercules Fund from the Flemish Government. L. Ding is acknowledge for his help with the GPA analysis. |
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UA @ admin @ c:irua:181236 |
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6889 |
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