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Author	Quintelier, M.; Perkisas, T.; Poppe, R.; Batuk, M.; Hendrickx, M.; Hadermann, J.
Title	Determination of spinel content in cycled Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ using three-dimensional electron diffraction and precession electron diffraction			Type	A1 Journal article
Year	2021	Publication	Symmetry-Basel	Abbreviated Journal	Symmetry-Basel
Volume	13	Issue	11	Pages	1989-17
Keywords	A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM); Electron microscopy for materials research (EMAT)
Abstract	Among lithium battery cathode materials, Li1.2Ni0.13Mn0.54Co0.13O2 (LR-NMC) has a high theoretical capacity, but suffers from voltage and capacity fade during cycling. This is partially ascribed to transition metal cation migration, which involves the local transformation of the honeycomb layered structure to spinel-like nano-domains. Determination of the honeycomb layered/spinel phase ratio from powder X-ray diffraction data is hindered by the nanoscale of the functional material and the domains, diverse types of twinning, stacking faults, and the possible presence of the rock salt phase. Determining the phase ratio from transmission electron microscopy imaging can only be done for thin regions near the surfaces of the crystals, and the intense beam that is needed for imaging induces the same transformation to spinel as cycling does. In this article, it is demonstrated that the low electron dose sufficient for electron diffraction allows the collection of data without inducing a phase transformation. Using calculated electron diffraction patterns, we demonstrate that it is possible to determine the volume ratio of the different phases in the particles using a pair-wise comparison of the intensities of the reflections. Using this method, the volume ratio of spinel structure to honeycomb layered structure is determined for a submicron sized crystal from experimental three-dimensional electron diffraction (3D ED) and precession electron diffraction (PED) data. Both twinning and the possible presence of the rock salt phase are taken into account. After 150 charge-discharge cycles, 4% of the volume in LR-NMC particles was transformed irreversibly from the honeycomb layered structure to the spinel structure. The proposed method would be applicable to other multi-phase materials as well.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000815310500001	Publication Date	2021-10-21
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2073-8994	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	1.457	Times cited		Open Access	OpenAccess
Notes				Approved	Most recent IF: 1.457
Call Number	UA @ admin @ c:irua:189468			Serial	7080
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Author	Kutukov, P.; Rumyantseva, M.; Krivetskiy, V.; Filatova, D.; Batuk, M.; Hadermann, J.; Khmelevsky, N.; Aksenenko, A.; Gaskov, A.
Title	Influence of Mono- and Bimetallic PtOx, PdOx, PtPdOx Clusters on CO Sensing by SnO2 Based Gas Sensors			Type	A1 Journal Article
Year	2018	Publication	Nanomaterials	Abbreviated Journal	Nanomaterials-Basel
Volume	8	Issue	11	Pages	917
Keywords	A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Abstract	To obtain a nanocrystalline SnO2 matrix and mono- and bimetallic nanocomposites SnO2/Pd, SnO2/Pt, and SnO2/PtPd, a flame spray pyrolysis with subsequent impregnation was used. The materials were characterized using X-ray diffraction (XRD), a single-point BET method, transmission electron microscopy (TEM), and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with energy dispersive X-ray (EDX) mapping. The electronic state of the metals in mono- and bimetallic clusters was determined using X-ray photoelectron spectroscopy (XPS). The active surface sites were investigated using the Fourier Transform infrared spectroscopy (FTIR) and thermo-programmed reduction with hydrogen (TPR-H-2) methods. The sensor response of blank SnO2 and nanocomposites had a carbon monoxide (CO) level of 6.7 ppm and was determined in the temperature range 60-300 degrees C in dry (Relative Humidity (RH) = 0%) and humid (RH = 20%) air. The sensor properties of the mono- and bimetallic nanocomposites were analyzed on the basis of information on the electronic state, the distribution of modifiers in SnO2 matrix, and active surface centers. For SnO2/PtPd, the combined effect of the modifiers on the electrophysical properties of SnO2 explained the inversion of sensor response from n- to p-types observed in dry conditions.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000451316100052	Publication Date	2018-11-07
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2079-4991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.553	Times cited	7	Open Access	Not_Open_Access
Notes	This research was funded by the Russian Ministry of Education and Sciences (Agreement No. 14.613.21.0075, RFMEFI61317X0075).			Approved	Most recent IF: 3.553
Call Number	EMAT @ emat @c:irua:155767			Serial	5139
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Author	Naberezhnyi, D.; Rumyantseva, M.; Filatova, D.; Batuk, M.; Hadermann, J.; Baranchikov, A.; Khmelevsky, N.; Aksenenko, A.; Konstantinova, E.; Gaskov, A.
Title	Effects of Ag additive in low temperature CO detection with In₂O₃ based gas sensors			Type	A1 Journal article
Year	2018	Publication	Nanomaterials	Abbreviated Journal
Volume	8	Issue	10	Pages	801
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Nanocomposites In2O3/Ag obtained by ultraviolet (UV) photoreduction and impregnation methods were studied as materials for CO sensors operating in the temperature range 25-250 degrees C. Nanocrystalline In2O3 and In2O3/Ag nanocomposites were characterized by X-ray diffraction (XRD), single-point Brunauer-Emmet-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with energy dispersive X-ray (EDX) mapping. The active surface sites were investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) spectroscopy and thermo-programmed reduction with hydrogen (TPR-H-2) method. Sensor measurements in the presence of 15 ppm CO demonstrated that UV treatment leads to a complete loss of In2O3 sensor sensitivity, while In2O3/Ag-UV nanocomposite synthesized by UV photoreduction demonstrates an increased sensor signal to CO at T < 200 degrees C. The observed high sensor response of the In2O3/Ag-UV nanocomposite at room temperature may be due to the realization of an additional mechanism of CO oxidation with participation of surface hydroxyl groups associated via hydrogen bonds.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000451174100057	Publication Date	2018-10-08
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2079-4991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited		Open Access
Notes				Approved	no
Call Number	UA @ admin @ c:irua:156335			Serial	7842
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Author	Guzzinati, G.; Altantzis, T.; Batuk, M.; De Backer, A.; Lumbeeck, G.; Samaee, V.; Batuk, D.; Idrissi, H.; Hadermann, J.; Van Aert, S.; Schryvers, D.; Verbeeck, J.; Bals, S.
Title	Recent Advances in Transmission Electron Microscopy for Materials Science at the EMAT Lab of the University of Antwerp			Type	A1 Journal article
Year	2018	Publication	Materials	Abbreviated Journal	Materials
Volume	11	Issue	11	Pages	1304
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The rapid progress in materials science that enables the design of materials down to the nanoscale also demands characterization techniques able to analyze the materials down to the same scale, such as transmission electron microscopy. As Belgium’s foremost electron microscopy group, among the largest in the world, EMAT is continuously contributing to the development of TEM techniques, such as high-resolution imaging, diffraction, electron tomography, and spectroscopies, with an emphasis on quantification and reproducibility, as well as employing TEM methodology at the highest level to solve real-world materials science problems. The lab’s recent contributions are presented here together with specific case studies in order to highlight the usefulness of TEM to the advancement of materials science.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000444112800041	Publication Date	2018-07-28
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1996-1944	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.654	Times cited	15	Open Access	OpenAccess
Notes	Fonds Wetenschappelijk Onderzoek, G.0502.18N, G.0267.18N, G.0120.12N, G.0365.15N, G.0934.17N, S.0100.18N AUHA13009 ; European Research Council, COLOURATOM 335078 ; Universiteit Antwerpen, GOA Solarpaint ; G. Guzzinati, T. Altantzis and A. De Backer have been supported by postdoctoral fellowship grants from the Research Foundation Flanders (FWO). Funding was also received from the European Research Council (starting grant no. COLOURATOM 335078), the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 770887), the Research Foundation Flanders (FWO, Belgium) through project fundings (G.0502.18N, G.0267.18N, G.0120.12N, G.0365.15N, G.0934.17N, S.0100.18N, G.0401.16N) and from the University of Antwerp through GOA project Solarpaint. Funding for the TopSPIN precession system under grant AUHA13009, as well as for the Qu-Ant-EM microscope, is acknowledged from the HERCULES Foundation. H. Idrissi is mandated by the Belgian National Fund for Scientific Research (F.R.S.-FNRS). (ROMEO:green; preprint:; postprint:can ; pdfversion:can); saraecas; ECAS_Sara;			Approved	Most recent IF: 2.654
Call Number	EMAT @ emat @c:irua:153737UA @ admin @ c:irua:153737			Serial	5064
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Author	Chizhov, A.; Vasiliev, R.; Rumyantseva, M.; Krylov, I.; Drozdov, K.; Batuk, M.; Hadermann, J.; Abakumov, A.; Gaskov, A.
Title	Light-activated sub-ppm NO₂ detection by hybrid ZnO/QD nanomaterials vs. charge localization in core-shell QD			Type	A1 Journal article
Year	2019	Publication	Frontiers in materials	Abbreviated Journal
Volume	6	Issue	6	Pages
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	New hybrid materials-photosensitized nanocomposites containing nanocrystal heterostructures with spatial charge separation, show high response for practically important sub-ppm level NO2 detection at room temperature. Nanocomposites ZnO/CdSe, ZnO/(CdS@CdSe), and ZnO/(ZnSe@CdS) were obtained by the immobilization of nanocrystals-colloidal quantum dots (QDs), on the matrix of nanocrystalline ZnO. The formation of crystalline core-shell structure of QDs was confirmed by HAADF-STEM coupled with EELS mapping. Optical properties of photosensitizers have been investigated by optical absorption and luminescence spectroscopy combined with spectral dependences of photoconductivity, which proved different charge localization regimes. Photoelectrical and gas sensor properties of nanocomposites have been studied at room temperature under green light (max = 535 nm) illumination in the presence of 0.12-2 ppm NO2 in air. It has been demonstrated that sensitization with type II heterostructure ZnSe@CdS with staggered gap provides the rapid growth of effective photoresponse with the increase in the NO2 concentration in air and the highest sensor sensitivity toward NO2. We believe that the use of core-shell QDs with spatial charge separation opens new possibilities in the development of light-activated gas sensors working without thermal heating.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000487641600002	Publication Date	2019-09-24
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2296-8016	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	1	Open Access
Notes	; This work was financially supported by RFBR grant No. 1653-76001 (RFBR – ERA.Net FONSENS 096) and in part by a grant from the St. Petersburg State University – Event 3-2018 (id: 26520408). AC acknowledges support from the RFBR grant No. 18-33-01004. ;			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:163776			Serial	5390
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Author	Marikutsa, A.; Rumyantseva, M.; Gaskov, A.; Batuk, M.; Hadermann, J.; Sarmadian, N.; Saniz, R.; Partoens, B.; Lamoen, D.
Title	Effect of zinc oxide modification by indium oxide on microstructure, adsorbed surface species, and sensitivity to CO			Type	A1 Journal article
Year	2019	Publication	Frontiers in materials	Abbreviated Journal
Volume	6	Issue	6	Pages
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract	Additives in semiconductor metal oxides are commonly used to improve sensing behavior of gas sensors. Due to complicated effects of additives on the materials microstructure, adsorption sites and reactivity to target gases the sensing mechanism with modified metal oxides is a matter of thorough research. Herein, we establish the promoting effect of nanocrystalline zinc oxide modification by 1-7 at.% of indium on the sensitivity to CO gas due to improved nanostructure dispersion and concentration of active sites. The sensing materials were synthesized via an aqueous coprecipitation route. Materials composition, particle size and BET area were evaluated using X-ray diffraction, nitrogen adsorption isotherms, high-resolution electron microscopy techniques and EDX-mapping. Surface species of chemisorbed oxygen, OH-groups, and acid sites were characterized by probe molecule techniques and infrared spectroscopy. It was found that particle size of zinc oxide decreased and the BET area increased with the amount of indium oxide. The additive was observed as amorphous indium oxide segregated on agglomerated ZnO nanocrystals. The measured concentration of surface species was higher on In2O3-modified zinc oxide. With the increase of indium oxide content, the sensor response of ZnO/In2O3 to CO was improved. Using in situ infrared spectroscopy, it was shown that oxidation of CO molecules was enhanced on the modified zinc oxide surface. The effect of modifier was attributed to promotion of surface OH-groups and enhancement of CO oxidation on the segregated indium ions, as suggested by DFT in previous work.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000461540600001	Publication Date	2019-03-15
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2296-8016	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	11	Open Access	OpenAccess
Notes	; Research was supported by the grant from Russian Science Foundation (project No. 18-73-00071). ;			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:158540			Serial	5205
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Author	Van Rompaey, S.; Dachraoui, W.; Turner, S.; Podyacheva, O.Y.; Tan, H.; Verbeeck, J.; Abakumov, A.; Hadermann, J.
Title	Layered oxygen vacancy ordering in Nb-doped SrCo_1-xFe_xO_3-\delta perovskite			Type	A1 Journal article
Year	2013	Publication	Zeitschrift für Kristallographie	Abbreviated Journal	Z Krist-Cryst Mater
Volume	228	Issue	1	Pages	28-34
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The crystal structure of SrCo0.7Fe0.2Nb0.1O2.72 was determined using a combination of precession electron diffraction (PED), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and spatially resolved electron energy loss spectroscopy (STEM-EELS). The structure has a tetragonal P4/mmm symmetry with cell parameters a = b = a(p), c = 2a(p) (a(p) being the cell parameter of the perovskite parent structure). Octahedral BO2 layers alternate with the anion-deficient BO1.4 layers, the different B cations are randomly distributed over both layers. The specific feature of the SrCo0.7Fe0.2NB0.1O2.72 microstructure is a presence of extensive nanoscale twinning resulting in domains with alignment of the tetragonal c-axis along all three cubic direction of the perovskite subcell.
Address
Corporate Author				Thesis
Publisher		Place of Publication	München	Editor
Language		Wos	000315475900004	Publication Date	2013-01-24
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2194-4946;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.179	Times cited	9	Open Access
Notes	Fwo; Countatoms			Approved	Most recent IF: 3.179; 2013 IF: NA
Call Number	UA @ lucian @ c:irua:107698UA @ admin @ c:irua:107698			Serial	1808
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Author	Meert, K.W.; Morozov, V.A.; Abakumov, A.M.; Hadermann, J.; Poelman, D.; Smet, P.F.
Title	Energy transfer in Eu³⁺ doped scheelites : use as thermographic phosphor			Type	A1 Journal article
Year	2014	Publication	Optics express	Abbreviated Journal	Opt Express
Volume	22	Issue	9	Pages	A961-A972
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	In this paper the luminescence of the scheelite-based CaGd2(1-x)Eu2x(WO4)4 solid solutions is investigated as a function of the Eu content and temperature. All phosphors show intense red luminescence due to the 5D0 7F2 transition in Eu3+, along with other transitions from the 5D1 and 5D0 excited states. For high Eu3+ concentrations the intensity ratio of the emission originating from the 5D1 and 5D0 levels has a non-conventional temperature dependence, which could be explained by a phonon-assisted cross-relaxation process. It is demonstrated that this intensity ratio can be used as a measure of temperature with high spatial resolution, allowing the use of these scheelites as thermographic phosphor. The main disadvantage of many thermographic phosphors, a decreasing signal for increasing temperature, is absent.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000335905300037	Publication Date	2014-04-22
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1094-4087;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.307	Times cited	47	Open Access
Notes				Approved	Most recent IF: 3.307; 2014 IF: 3.488
Call Number	UA @ lucian @ c:irua:117067			Serial	1044
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Author	Vishwakarma, M.; Karakulina, O.M.; Abakumov, A.M.; Hadermann, J.; Mehta, B.R.
Title	Nanoscale Characterization of Growth of Secondary Phases in Off-Stoichiometric CZTS Thin Films			Type	A1 Journal article
Year	2018	Publication	Journal of nanoscience and nanotechnology	Abbreviated Journal	J Nanosci Nanotechno
Volume	18	Issue	3	Pages	1688-1695
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	The presence of secondary phases is one of the main issues that hinder the growth of pure kesterite Cu2ZnSnS4 (CZTS) based thin films with suitable electronic and junction properties for efficient solar cell devices. In this work, CZTS thin films with varied Zn and Sn content have been prepared by RF-power controlled co-sputtering deposition using Cu, ZnS and SnS targets and a subsequent sulphurization step. Detailed TEM investigations show that the film shows a layered structure with the majority of the top layer being the kesterite phase. Depending on the initial thin film composition, either about ~1 μm Cu-rich and Zn-poor kesterite or stoichiometric CZTS is formed as top layer. X-ray diffraction, Raman spectroscopy and transmission electron microscopy reveal the presence of Cu2−x S, ZnS and SnO2 minor secondary phases in the form of nanoinclusions or nanoparticles or intermediate layers.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000426033400022	Publication Date	2018-03-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1533-4880	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	1.483	Times cited		Open Access	Not_Open_Access
Notes	Manoj Vishwakarma acknowl- edges IIT Delhi for MHRD fellowship. Professor B. R. Mehta acknowledges the support of the Schlumberger chair professorship. Manoj Vishwakarma, Joke Hadermann and Olesia M. karakulina acknowledge support provided by InsoL-DST. Manoj Vishwakarma acknowledges sup- port provided by CSIR funded projects and the support of DST-FIST Raman facility. References			Approved	Most recent IF: 1.483
Call Number	EMAT @ emat @c:irua:147505			Serial	4775
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Author	Kelchtermans, A.; Adriaensens, P.; Slocombe, D.; Kuznetsov, V.L.; Hadermann, J.; Riskin, A.; Elen, K.; Edwards, P.P.; Hardy, A.; Van Bael, M.K.
Title	Increasing the solubility limit for tetrahedral aluminium in ZnO:Al nanorods by variation in synthesis parameters			Type	A1 Journal article
Year	2015	Publication	Journal of nanomaterials	Abbreviated Journal	J Nanomater
Volume	2015	Issue	2015	Pages	1-8
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Nanocrystalline ZnO:Al nanoparticles are suitable building blocks for transparent conductive layers. As the concentration of substitutional tetrahedral Al is an important factor for improving conductivity, here we aim to increase the fraction of substitutional Al. To this end, synthesis parameters of a solvothermal reaction yielding ZnO:Al nanorods were varied. A unique set of complementary techniques was combined to reveal the exact position of the aluminium ions in the ZnO lattice and demonstrated its importance in order to evaluate the potential of ZnO:Al nanocrystals as optimal building blocks for solution deposited transparent conductive oxide layers. Both an extension of the solvothermal reaction time and stirring during solvothermal treatment result in a higher total tetrahedral aluminium content in the ZnO lattice. However, only the longer solvothermal treatment effectively results in an increase of the substitutional positions aimed for.
Address
Corporate Author				Thesis
Publisher		Place of Publication	New York, N.Y.	Editor
Language		Wos	000358516300001	Publication Date	2015-07-12
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1687-4110;1687-4129;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	1.871	Times cited	2	Open Access
Notes	FWO; Methusalem			Approved	Most recent IF: 1.871; 2015 IF: 1.644
Call Number	c:irua:124426			Serial	1600
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Author	Watanabe, Y.; Hyeon-Deuk, K.; Yamamoto, T.; Yabuuchi, M.; Karakulina, O.M.; Noda, Y.; Kurihara, T.; Chang, I.-Y.; Higashi, M.; Tomita, O.; Tassel, C.; Kato, D.; Xia, J.; Goto, T.; Brown, C.M.; Shimoyama, Y.; Ogiwara, N.; Hadermann, J.; Abakumov, A.M.; Uchida, S.; Abe, R.; Kageyama, H.
Title	Polyoxocationic antimony oxide cluster with acidic protons			Type	A1 Journal article
Year	2022	Publication	Science Advances	Abbreviated Journal
Volume	8	Issue	24	Pages	eabm5379-8
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	The success and continued expansion of research on metal-oxo clusters owe largely to their structural richness and wide range of functions. However, while most of them known to date are negatively charged polyoxometalates, there is only a handful of cationic ones, much less functional ones. Here, we show an all-inorganic hydroxyiodide [H(10.)7Sb(32.1)O(44)][H2.1Sb2.1I8O6][Sb0.76I6](2)center dot 25H(2)O (HSbOI), forming a face-centered cubic structure with cationic Sb32O44 clusters and two types of anionic clusters in its interstitial spaces. Although it is submicrometer in size, electron diffraction tomography of HSbOI allowed the construction of the initial structural model, followed by powder Rietveld refinement to reach the final structure. The cationic cluster is characterized by the presence of acidic protons on its surface due to substantial Sb3+ deficiencies, which enables HSbOI to serve as an excellent solid acid catalyst. These results open up a frontier for the exploration and functionalization of cationic metal-oxo clusters containing heavy main group elements.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000812533800008	Publication Date	2022-06-17
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2375-2548	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	13.6	Times cited		Open Access	OpenAccess
Notes				Approved	Most recent IF: 13.6
Call Number	UA @ admin @ c:irua:189689			Serial	7091
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Author	Ranjbar, S.; Hadipour, A.; Vermang, B.; Batuk, M.; Hadermann, J.; Garud, S.; Sahayaraj, S.; Meuris, M.; Brammertz, G.; da Cunha, A.F.; Poortmans, J.
Title	P-N Junction Passivation in Kesterite Solar Cells by Use of Solution-Processed TiO2 Layer			Type	A1 Journal article
Year	2017	Publication	IEEE journal of photovoltaics	Abbreviated Journal	Ieee J Photovolt
Volume	7	Issue	7	Pages	1130-1135
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	In this work, we used a solution-processed TiO2 layer between Cu2ZnSnSe4 and CdS buffer layer to reduce the recombination at the p–n junction. Introducing the TiO2 layer showed a positive impact on VOC but fill factor and efficiency decreased. Using a KCN treatment, we could create openings in the TiO2 layer, as confirmed by transmission electron microscopy measurements. Formation of these openings in the TiO2 layer led to the improvement of the short-circuit current, fill factor, and the efficiency of the modified solar cells.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000404258900026	Publication Date	2017-04-25
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2156-3381	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.712	Times cited	2	Open Access	OpenAccess
Notes	This work was supported in part by the European Union’s Horizon 2020 research and innovation program under Grant 640868, in part by the Flemish government, Department Economy, Science and Innovation, in part by the FEDER funds through the COMPETE 2020 Programme, and in part by the National Funds through FCT – Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013. The work of S. Ranjbar was supported by the Portuguese Science and Technology Foundation through Ph.D. grant SFRH/BD/78409/2011. The work of B. Vermang was supported by the Flemish Research Foundation FWO (mandate 12O4215N).			Approved	Most recent IF: 3.712
Call Number	EMAT @ emat @ c:irua:143986			Serial	4583
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Author	Missen, O.P.; Mills, S.J.; Canossa, S.; Hadermann, J.; Nenert, G.; Weil, M.; Libowitzky, E.; Housley, R.M.; Artner, W.; Kampf, A.R.; Rumsey, M.S.; Spratt, J.; Momma, K.; Dunstan, M.A.
Title	Polytypism in mcalpineite : a study of natural and synthetic Cu₃TeO₆			Type	A1 Journal article
Year	2022	Publication	Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials (Online)	Abbreviated Journal	Acta Crystallogr B
Volume	78	Issue	1	Pages
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Synthetic and naturally occurring forms of tricopper orthotellurate, (Cu3TeO6)-Te-II-O-IV (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, (Cu3TeO6)-Te-II-O-IV is shown to occur in two polytypes. The higher-symmetric (Cu3TeO6)-Te-II-O-IV-1C polytype is cubic, space group 1a (3) over bar, with a = 9.537 (1) angstrom and V = 867.4 (3) angstrom(3) as reported in previous studies. The 1C polytype is a well characterized structure consisting of alternating layers of (CuO6)-O-II octahedra and both (CuO6)-O-II and (TeO6)-O-VI octahedra in a patchwork arrangement. The structure of the lower-symmetric orthorhombic (Cu3TeO6)-Te-II-O-IV-2O polytype was determined for the first time in this study by 3D ED and verified by Rietveld refinement. The 2O polytype crystallizes in space group Pcca, with a = 9.745 (3) angstrom, b = 9.749 (2) angstrom, c = 9.771 (2) angstrom and V = 928.3 (4) angstrom(3) . High-precision XRPD data were also collected on (Cu3TeO6)-Te-II-O-IV-2O to verify the lower-symmetric structure by performing a Rietveld refinement. The resultant structure is identical to that determined by 3D ED, with unit-cell parameters a = 9.56157 (19) angstrom, b = 9.55853 (11) angstrom, c = 9.62891 (15) angstrom and V = 880.03 (2) angstrom(3) . The lower symmetry of the 2O polytype is a consequence of a different cation ordering arrangement, which involves the movement of every second (CuO6)-O-II and (TeO6)-O-VI octahedral layer by (1/4, 1/4, 0), leading to an offset of (TeO6)-O-VI and (CuO6)-O-II octahedra in every second layer giving an ABAB* stacking arrangement. Syntheses of (Cu3TeO6)-Te-II-O-IV showed that low-temperature (473 K) hydrothermal conditions generally produce the 2O polytype. XRPD measurements in combination with Raman spectroscopic analysis showed that most natural mcalpineite is the orthorhombic 2O polytype. Both XRPD and Raman spectroscopy measurements may be used to differentiate between the two polytypes of (Cu3TeO6)-Te-II-O-IV. In Raman spectroscopy, (Cu3TeO6)-Te-II-O-IV-1C has a single strong band around 730 cm(-1), whereas (Cu3TeO6)-Te-II-O-IV-2O shows a broad double maximum with bands centred around 692 and 742 cm(-1).
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000752899700003	Publication Date	2022-01-18
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2052-5206	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	1.9	Times cited		Open Access	OpenAccess
Notes				Approved	Most recent IF: 1.9
Call Number	UA @ admin @ c:irua:186529			Serial	6962
Permanent link to this record



Author	Hadermann, J.; Palatinus, L.
Title	Introducton to the special issue on electron crystallography			Type	Editorial
Year	2019	Publication	And Materials	Abbreviated Journal
Volume	75	Issue	4	Pages	462-462
Keywords	Editorial; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000480512600028	Publication Date	2019-08-05
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN		ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	2	Open Access
Notes	; ;			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:161845			Serial	5389
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Author	Callaert, C.; Bercx, M.; Lamoen, D.; Hadermann, J.
Title	Interstitial defects in the van der Waals gap of Bi₂Se₃			Type	A1 Journal article
Year	2019	Publication	Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials (Online)	Abbreviated Journal	Acta Crystallogr B
Volume	75	Issue	4	Pages	717-732
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Bi<sub>2</sub>Se<sub>3</sub>is a thermoelectric material and a topological insulator. It is slightly conducting in its bulk due to the presence of defects and by controlling the defects different physical properties can be fine tuned. However, studies of the defects in this material are often contradicting or inconclusive. Here, the defect structure of Bi<sub>2</sub>Se<sub>3</sub>is studied with a combination of techniques: high-resolution scanning transmission electron microscopy (HR-STEM), high-resolution energy-dispersive X-ray (HR-EDX) spectroscopy, precession electron diffraction tomography (PEDT), X-ray diffraction (XRD) and first-principles calculations using density functional theory (DFT). Based on these results, not only the observed defects are discussed, but also the discrepancies in results or possibilities across the techniques. STEM and EDX revealed interstitial defects with mainly Bi character in an octahedral coordination in the van der Waals gap, independent of the applied sample preparation method (focused ion beam milling or cryo-crushing). The inherent character of these defects is supported by their observation in the structure refinement of the EDT data. Moreover, the occupancy probability of the defects determined by EDT is inversely proportional to their corresponding DFT calculated formation energies. STEM also showed the migration of some atoms across and along the van der Waals gap. The kinetic barriers calculated using DFT suggest that some paths are possible at room temperature, while others are most probably beam induced.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000480512600024	Publication Date	2019-08-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2052-5206	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.032	Times cited		Open Access
Notes	University of Antwerp, 31445 ; Acknowledgements We thank Artem M. Abakumov for providing the original Bi2Se3 sample and are also very grateful to Christophe Vandevelde for trying repeatedly to get good single crystal X-ray diffraction data out of each of our failed attempts at making an undeformed single crystal. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the FWO-Vlaanderen and the Flemish Government-department EWI.			Approved	Most recent IF: 2.032
Call Number	EMAT @ emat @c:irua:161847			Serial	5295
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Author	Batuk, D.; Batuk, M.; Abakumov, A.M.; Hadermann, J.
Title	Synergy between transmission electron microscopy and powder diffraction : application to modulated structures			Type	A1 Journal article
Year	2015	Publication	Acta crystallographica: section B: structural science	Abbreviated Journal	Acta Crystallogr B
Volume	71	Issue	71	Pages	127-143
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The crystal structure solution of modulated compounds is often very challenging, even using the well established methodology of single-crystal X-ray crystallography. This task becomes even more difficult for materials that cannot be prepared in a single-crystal form, so that only polycrystalline powders are available. This paper illustrates that the combined application of transmission electron microscopy (TEM) and powder diffraction is a possible solution to the problem. Using examples of anion-deficient perovskites modulated by periodic crystallographic shear planes, it is demonstrated what kind of local structural information can be obtained using various TEM techniques and how this information can be implemented in the crystal structure refinement against the powder diffraction data. The following TEM methods are discussed: electron diffraction (selected area electron diffraction, precession electron diffraction), imaging (conventional high-resolution TEM imaging, high-angle annular dark-field and annular bright-field scanning transmission electron microscopy) and state-of-the-art spectroscopic techniques (atomic resolution mapping using energy-dispersive X-ray analysis and electron energy loss spectroscopy).
Address
Corporate Author				Thesis
Publisher		Place of Publication	Copenhagen	Editor
Language		Wos	000352166500002	Publication Date	2015-04-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2052-5206;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.032	Times cited	11	Open Access
Notes	Fwo G039211n			Approved	Most recent IF: 2.032; 2015 IF: NA
Call Number	c:irua:124411			Serial	3408
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Author	Poppe, R.; Roth, N.; Neder, R.B.; Palatinus, L.; Iversen, B.B.; Hadermann, J.
Title	Refining short-range order parameters from the three-dimensional diffuse scattering in single-crystal electron diffraction data			Type	A1 Journal article
Year	2024	Publication	IUCrJ	Abbreviated Journal
Volume	11	Issue	1	Pages	82-91
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Our study compares short-range order parameters refined from the diffuse scattering in single-crystal X-ray and single-crystal electron diffraction data. Nb0.84CoSb was chosen as a reference material. The correlations between neighbouring vacancies and the displacements of Sb and Co atoms were refined from the diffuse scattering using a Monte Carlo refinement in DISCUS. The difference between the Sb and Co displacements refined from the diffuse scattering and the Sb and Co displacements refined from the Bragg reflections in single-crystal X-ray diffraction data is 0.012 (7) angstrom for the refinement on diffuse scattering in single-crystal X-ray diffraction data and 0.03 (2) angstrom for the refinement on the diffuse scattering in single-crystal electron diffraction data. As electron diffraction requires much smaller crystals than X-ray diffraction, this opens up the possibility of refining short-range order parameters in many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	001168018300012	Publication Date	2023-12-14
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2052-2525	ISBN		Additional Links	UA library record; WoS full record
Impact Factor		Times cited		Open Access
Notes				Approved	no
Call Number	UA @ admin @ c:irua:205513			Serial	9170
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Author	Poppe, R.; Vandemeulebroucke, D.; Neder, R.B.; Hadermann, J.
Title	Quantitative analysis of diffuse electron scattering in the lithium-ion battery cathode material Li_1.2Ni_0.13Mn_0.54Co_0.13O₂			Type	A1 Journal article
Year	2022	Publication	IUCrJ	Abbreviated Journal	Iucrj
Volume	9	Issue	5	Pages	695-704
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	In contrast to perfectly periodic crystals, materials with short-range order produce diffraction patterns that contain both Bragg reflections and diffuse scattering. To understand the influence of short-range order on material properties, current research focuses increasingly on the analysis of diffuse scattering. This article verifies the possibility to refine the short-range order parameters in submicrometre-sized crystals from diffuse scattering in single-crystal electron diffraction data. The approach was demonstrated on Li<sub>1.2</sub>Ni<sub>0.13</sub>Mn<sub>0.54</sub>Co<sub>0.13</sub>O<sub>2</sub>, which is a state-of-the-art cathode material for lithium-ion batteries. The intensity distribution of the 1D diffuse scattering in the electron diffraction patterns of Li<sub>1.2</sub>Ni<sub>0.13</sub>Mn<sub>0.54</sub>Co<sub>0.13</sub>O<sub>2</sub>depends on the number of stacking faults and twins in the crystal. A model of the disorder in Li<sub>1.2</sub>Ni<sub>0.13</sub>Mn<sub>0.54</sub>Co<sub>0.13</sub>O<sub>2</sub>was developed and both the stacking fault probability and the percentage of the different twins in the crystal were refined using an evolutionary algorithm in<italic>DISCUS</italic>. The approach was applied on reciprocal space sections reconstructed from 3D electron diffraction data since they exhibit less dynamical effects compared with in-zone electron diffraction patterns. A good agreement was achieved between the calculated and the experimental intensity distribution of the diffuse scattering. The short-range order parameters in submicrometre-sized crystals can thus successfully be refined from the diffuse scattering in single-crystal electron diffraction data using an evolutionary algorithm in<italic>DISCUS</italic>.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000852551800018	Publication Date	2022-09-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2052-2525	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.9	Times cited		Open Access	OpenAccess
Notes	The research leading to these results has received funding from the Research Foundation Flanders, G035619N G040116N ;			Approved	Most recent IF: 3.9
Call Number	EMAT @ emat @c:irua:190647			Serial	7105
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Author	Poltavets, V.V.; Lokshin, K.A.; Nevidomskyy, A.H.; Croft, M.; Tyson, T.A.; Hadermann, J.; Van Tendeloo, G.; Egami, T.; Kotliar, G.; ApRoberts-Warren, N.; Dioguardi, A.P.; Curro, N.J.; Greenblatt, M.;
Title	Bulk magnetic order in a two-dimensional Ni¹⁺/Ni²⁺ (d⁹/d⁸) nickelate, isoelectronic with superconducting cuprates			Type	A1 Journal article
Year	2010	Publication	Physical review letters	Abbreviated Journal	Phys Rev Lett
Volume	104	Issue	20	Pages	206403
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The Ni(1+)/Ni(2+) states of nickelates have the identical (3d(9)/3d(8)) electronic configuration as Cu(2+)/Cu(3+) in the high temperature superconducting cuprates, and are expected to show interesting properties. An intriguing question is whether mimicking the electronic and structural features of cuprates would also result in superconductivity in nickelates. Here we report experimental evidence for a bulklike magnetic transition in La(4)Ni(3)O(8) at 105 K. Density functional theory calculations relate the transition to a spin density wave nesting instability of the Fermi surface.
Address
Corporate Author				Thesis
Publisher		Place of Publication	New York, N.Y.	Editor
Language		Wos	000277945900033	Publication Date	2010-05-19
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0031-9007;1079-7114;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	8.462	Times cited	35	Open Access
Notes				Approved	Most recent IF: 8.462; 2010 IF: 7.622
Call Number	UA @ lucian @ c:irua:95613			Serial	260
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Author	Sanchez-Barriga, J.; Aguilera, I.; Yashina, L., V; Tsukanova, D.Y.; Freyse, F.; Chaika, A.N.; Callaert, C.; Abakumov, A.M.; Hadermann, J.; Varykhalov, A.; Rienks, E.D.L.; Bihlmayer, G.; Blugel, S.; Rader, O.
Title	Anomalous behavior of the electronic structure of (Bi_1-xIn_x)₂Se₃across the quantum phase transition from topological to trivial insulator			Type	A1 Journal article
Year	2018	Publication	Physical review B	Abbreviated Journal
Volume	98	Issue	23	Pages	235110
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Using spin- and angle-resolved photoemission spectroscopy and relativistic many-body calculations, we investigate the evolution of the electronic structure of (Bi1-xInx)(2)Se-3)(2)Se-3 bulk single crystals around the critical point of the trivial to topological insulator quantum-phase transition. By increasing x, we observe how a surface gap opens at the Dirac point of the initially gapless topological surface state of Bi2Se3, leading to the existence of massive fermions. The surface gap monotonically increases for a wide range of x values across the topological and trivial sides of the quantum-phase transition. By means of photon-energy-dependent measurements, we demonstrate that the gapped surface state survives the inversion of the bulk bands which occurs at a critical point near x = 0.055. The surface state exhibits a nonzero in-plane spin polarization which decays exponentially with increasing x, and which persists in both the topological and trivial insulator phases. Our calculations reveal qualitative agreement with the experimental results all across the quantum-phase transition upon the systematic variation of the spin-orbit coupling strength. A non-time-reversal symmetry-breaking mechanism of bulk-mediated scattering processes that increase with decreasing spin-orbit coupling strength is proposed as explanation.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000452322800003	Publication Date	2018-12-05
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited		Open Access
Notes				Approved	no
Call Number	UA @ admin @ c:irua:156240			Serial	7462
Permanent link to this record



Author	Augustyns, V.; van Stiphout, K.; Joly, V.; Lima, T.A.L.; Lippertz, G.; Trekels, M.; Menendez, E.; Kremer, F.; Wahl, U.; Costa, A.R.G.; Correia, J.G.; Banerjee, D.; Gunnlaugsson, H.P.; von Bardeleben, J.; Vickridge, I.; Van Bael, M.J.; Hadermann, J.; Araujo, J.P.; Temst, K.; Vantomme, A.; Pereira, L.M.C.
Title	Evidence of tetragonal distortion as the origin of the ferromagnetic ground state in gamma-Fe nanoparticles			Type	A1 Journal article
Year	2017	Publication	Physical review B	Abbreviated Journal	Phys Rev B
Volume	96	Issue	17	Pages	174410
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	<script type='text/javascript'>document.write(unpmarked('gamma-Fe and related alloys are model systems of the coupling between structure and magnetism in solids. Since different electronic states (with different volumes and magnetic ordering states) are closely spaced in energy, small perturbations can alter which one is the actual ground state. Here, we demonstrate that the ferromagnetic state of gamma-Fe nanoparticles is associated with a tetragonal distortion of the fcc structure. Combining a wide range of complementary experimental techniques, including low-temperature Mossbauer spectroscopy, advanced transmission electron microscopy, and synchrotron radiation techniques, we unambiguously identify the tetragonally distorted ferromagnetic ground state, with lattice parameters a = 3.76(2) angstrom and c = 3.50(2) angstrom, and a magnetic moment of 2.45(5) mu(B) per Fe atom. Our findings indicate that the ferromagnetic order in nanostructured gamma-Fe is generally associated with a tetragonal distortion. This observation motivates a theoretical reassessment of the electronic structure of gamma-Fe taking tetragonal distortion into account.'));
Address
Corporate Author				Thesis
Publisher	American Physical Society	Place of Publication	New York, N.Y	Editor
Language		Wos	000414525200005	Publication Date	2017-11-07
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	1	Open Access	OpenAccess
Notes	; The authors thank the Fund for Scientific Research-Flanders, the Concerted Research Action of the KU Leuven (GOA/14/007), the KU Leuven BOF (STRT/14/002), the Hercules Foundation, the Portuguese Foundation for Science and Technology (CERN/FIS-NUC/0004/2015), and the European Union Seventh Framework through ENSAR2 (European Nuclear Science and Applications Research, Project No. 654002), and SPIRIT (Support of Public and Industrial Research Using Ion Beam Technology, Contract No. 227012). We acknowledge the European Synchrotron Radiation Facility (ESRF) for providing beam time (experiments 26-01-1018, 26-01-1057, 20-02-728, HC-1850, HC-2208), as well as C. Baehtz, N. Boudet, and N. Blancand for support during the experiments. We acknowledge the ISOLDE-CERN facility for providing beam time (experiment IS580) and technical assistance. The authors (L.M.C.P., F.K.) acknowledge the facilities and the scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility at the Centre for Advanced Microscopy, Australian National University. We also acknowledge the contribution of Prof. Mark Ridgway (Australian National University), who passed away before the work was completed. ;			Approved	Most recent IF: 3.836
Call Number	UA @ lucian @ c:irua:147387			Serial	4873
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Author	Abakumov, A.M.; Batuk, D.; Tsirlin, A.A.; Prescher, C.; Dubrovinsky, L.; Sheptyakov, D.V.; Schnelle, W.; Hadermann, J.; Van Tendeloo, G.
Title	Frustrated pentagonal Cairo lattice in the non-collinear antiferromagnet Bi₄Fe₅O₁₃F			Type	A1 Journal article
Year	2013	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
Volume	87	Issue	2	Pages	024423-24429
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We report on the crystal structure and magnetism of the iron-based oxyfluoride Bi4Fe5O13F, a material prototype of the Cairo pentagonal spin lattice. The crystal structure of Bi4Fe5O13F is determined by a combination of neutron diffraction, synchrotron x-ray diffraction, and transmission electron microscopy. It comprises layers of FeO6 octahedra and FeO4 tetrahedra forming deformed pentagonal units. The topology of these layers resembles a pentagonal least-perimeter tiling, which is known as the Cairo lattice. This topology gives rise to frustrated exchange couplings and underlies a sequence of magnetic transitions at T-1 = 62 K, T-2 = 71 K, and T-N = 178 K, as determined by thermodynamic measurements and neutron diffraction. Below T-1, Bi4Fe5O13F forms a fully ordered non-collinear antiferromagnetic structure, whereas the magnetic state between T-1 and T-N may be partially disordered according to the sizable increase in the magnetic entropy at T-1 and T-2. Bi4Fe5O13F reveals unanticipated magnetic transitions on the pentagonal Cairo spin lattice and calls for a further work on finite-temperature properties of this strongly frustrated spin model. DOI: 10.1103/PhysRevB.87.024423
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000314224800002	Publication Date	2013-02-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	17	Open Access
Notes				Approved	Most recent IF: 3.836; 2013 IF: 3.664
Call Number	UA @ lucian @ c:irua:107688			Serial	1293
Permanent link to this record



Author	Vishwakarma, M.; Varandani, D.; Hendrickx, M.; Hadermann, J.; Mehta, B.R.
Title	Nanoscale photovoltage mapping in CZTSe/CuxSe heterostructure by using kelvin probe force microscopy			Type	A1 Journal article
Year	2020	Publication	Materials Research Express	Abbreviated Journal
Volume	7	Issue	1	Pages	016418
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	In the present work, kelvin probe force microscopy (KPFM) technique has been used to study the CZTSe/CuxSe bilayer interface prepared by multi-step deposition and selenization process of metal precursors. Transmission electron microscopy (TEM) confirmed the bilayer configuration of the CZTSe/CuxSe sample. Two configuration modes (surface mode and junction mode) in KPFM have been employed in order to measure the junction voltage under illumination conditions. The results show that CZTSe/CuxSe has small junction voltage of similar to 21 mV and the presence of CuxSe secondary phase in the CZTSe grain boundaries changes the workfunction of the local grain boundaries region. The negligible photovoltage difference between grain and grain boundaries in photovoltage image indicates that CuxSe phase deteriorates the higher photovoltage at grain boundaries normally observed in CZTSe based device. These results can be important for understanding the role of secondary phases in CZTSe based junction devices.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000520120900001	Publication Date	2019-12-27
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN		ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited		Open Access	OpenAccess
Notes	; Authors acknowledges support provided DST in the forms of InSOL and Indo-Swiss projects. We also acknowledge Joke Hadermann EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Belgium for helping in TEM measurements. M V Manoj Vishwakarma acknowledges IIT Delhi for MHRD fellowship. Prof B R Mehta acknowledges the support of the Schlumberger chair professorship. M V also acknowledges the support of DST-FIST Raman facility. ;			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:167843			Serial	6567
Permanent link to this record



Author	Piorra, A.; Hrkac, V.; Wolff, N.; Zamponi, C.; Duppel, V.; Hadermann, J.; Kienle, L.; Quandt, E.
Title	(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃ thin films prepared by PLD : relaxor properties and complex microstructure			Type	A1 Journal article
Year	2019	Publication	Journal of applied physics	Abbreviated Journal	J Appl Phys
Volume	125	Issue	24	Pages	244103
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Ferroelectric lead-free thin films of the composition (Ba0.85Ca0.15)(Ti0.9Zr0.1)O-3 (BCZT) were deposited by pulsed laser deposition on Pt/TiO2/SiO2/Si substrates using a ceramic BCZT target prepared by a conventional solid state reaction. The target material itself shows a piezoelectric coefficient of d(33)=640pm/V. The (111) textured thin films possess a thickness of up to 1.1 mu m and exhibit a clamped piezoelectric response f of up to 190pm/V, a dielectric coefficient of (r)=2000 at room temperature, and a pronounced relaxor behavior. As indicated by transmission electron microscopy, the thin films are composed of longitudinal micrometersized columns with similar to 100nm lateral dimension that are separated at twin- and antiphase boundaries. The superposition phenomena according to this columnar growth were simulated based on suitable supercells. The major structural component is described as a tetragonal distorted variant of the perovskite parent type; however, frequently coherently intergrown nanodomains were observed indicating a much more complex structure that is characterized by a 7-layer modulation along the growth direction of the films.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000474439600002	Publication Date	2019-06-25
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0021-8979; 1089-7550	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.068	Times cited		Open Access
Notes	; The authors want to thank Dr. Martina Luysberg and Dr. Lothar Houben from the Ernst Ruska Centre in Julich for discussion and CS-corrected microscopy. Funding of this work via the DFG (No. CRC1261) “Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics” and the PAK902 is gratefully acknowledged. ;			Approved	Most recent IF: 2.068
Call Number	UA @ admin @ c:irua:161310			Serial	5399
Permanent link to this record



Author	Vishwakarma, M.; Thota, N.; Karakulina, O.; Hadermann, J.; Mehta, B.R.
Title	Role of graphene inter layer on the formation of the MoS₂ – CZTS interface during growth			Type	P1 Proceeding
Year	2018	Publication	(icc-2017)	Abbreviated Journal
Volume		Issue		Pages
Keywords	P1 Proceeding; Electron microscopy for materials research (EMAT)
Abstract	The growth of MoS2 layer near the Mo/CZTS interface during sulphurization process can have an impact on back contact cell parameters (series resistance and fill factor) depending upon the thickness or quality of MoS2. This study reports the dependence of the thickness of interfacial MoS2 layer on the growth of graphene at the interface between molybdenum back contact and deposited CZTS layer. The graphene layer reduces the accumulation of Zn/ZnS, Sn/SnO2 and formation of pores near the MoS2-CZTS interface. The use of graphene as interface layer can be potentially useful for improving the quality of Mo/MoS2/CZTS interface.
Address
Corporate Author				Thesis
Publisher	Amer inst physics	Place of Publication	Melville	Editor
Language		Wos	000436313003046	Publication Date	2018-05-09
Series Editor		Series Title		Abbreviated Series Title
Series Volume	1953	Series Issue		Edition
ISSN	978-0-7354-1648-2; 0094-243x; 0094-243x	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	1	Open Access	OpenAccess
Notes	; The authors acknowledge support provided by DST project. M.V. acknowledges IIT Delhi for MHRD fellowship. Prof. B. R. Mehta acknowledges the support of the Schlumberger chair professorship. ;			Approved	Most recent IF: NA
Call Number	UA @ lucian @ c:irua:153203			Serial	5126
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Author	Blandy, J.N.; Abakumov, A.M.; Christensen, K.E.; Hadermann, J.; Adamson, P.; Cassidy, S.J.; Ramos, S.; Free, D.G.; Cohen, H.; Woodruff, D.N.; Thompson, A.L.; Clarke, S.J.;
Title	Soft chemical control of the crystal and magnetic structure of a layered mixed valent manganite oxide sulfide			Type	A1 Journal article
Year	2015	Publication	APL materials	Abbreviated Journal	Apl Mater
Volume	3	Issue	3	Pages	041520
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Oxidative deintercalation of copper ions from the sulfide layers of the layered mixed-valent manganite oxide sulfide Sr2MnO2Cu1.5S2 results in control of the copper-vacancy modulated superstructure and the ordered arrangement of magnetic moments carried by the manganese ions. This soft chemistry enables control of the structures and properties of these complex materials which complement mixed-valent perovskite and perovskite-related transition metal oxides. (C) 2015 Author(s).
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000353828400027	Publication Date	2015-04-21
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2166-532X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	4.335	Times cited	5	Open Access
Notes				Approved	Most recent IF: 4.335; 2015 IF: NA
Call Number	c:irua:126021			Serial	3049
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Author	Buffière, M.; Brammertz, G.; Batuk, M.; Verbist, C.; Mangin, D.; Koble, C.; Hadermann, J.; Meuris, M.; Poortmans, J.
Title	Microstructural analysis of 9.7% efficient Cu₂ZnSnSe₄ thin film solar cells			Type	A1 Journal article
Year	2014	Publication	Applied physics letters	Abbreviated Journal	Appl Phys Lett
Volume	105	Issue	18	Pages	183903
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	This work presents a detailed analysis of the microstructure and the composition of our record Cu 2ZnSnSe4 (CZTSe)-CdS-ZnO solar cell with a total area efficiency of 9.7%. The average composition of the CZTSe crystallites is Cu 1.94 Zn 1.12Sn0.95Se3.99. Large crystals of ZnSe secondary phase (up to 400 nm diameter) are observed at the voids between the absorber and the back contact, while smaller ZnSe domains are segregated at the grain boundaries and close to the surface of the CZTSe grains. An underlying layer and some particles of Cu xSe are observed at the Mo-MoSe2-Cu2ZnSnSe4 interface. The free surface of the voids at the back interface is covered by an amorphous layer containing Cu, S, O, and C, while the presence of Cd, Na, and K is also observed in this region.
Address
Corporate Author				Thesis
Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
Language		Wos	000345000000086	Publication Date	2014-11-08
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0003-6951;1077-3118;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.411	Times cited	17	Open Access
Notes				Approved	Most recent IF: 3.411; 2014 IF: 3.302
Call Number	UA @ lucian @ c:irua:121329			Serial	2038
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Author	Ulu Okudur, F.; Batuk, M.; Hadermann, J.; Safari, M.; De Sloovere, D.; Kumar Mylavarapu, S.; Joos, B.; D'Haen, J.; Van Bael, M.K.; Hardy, A.
Title	Solution-gel-based surface modification of LiNi_0.5Mn_1.5O_4-δ with amorphous Li-Ti-O coating			Type	A1 Journal article
Year	2023	Publication	RSC advances	Abbreviated Journal
Volume	13	Issue	47	Pages	33146-33158
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	LNMO (LiNi0.5Mn1.5O4-delta) is a high-energy density positive electrode material for lithium ion batteries. Unfortunately, it suffers from capacity loss and impedance rise during cycling due to electrolyte oxidation and electrode/electrolyte interface instabilities at high operating voltages. Here, a solution-gel synthesis route was used to coat 0.5-2.5 mu m LNMO particles with amorphous Li-Ti-O (LTO) for improved Li conduction, surface structural stability and cyclability. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis coupled with energy dispersive X-ray (EDX) showed Ti-rich amorphous coatings/islands or Ti-rich spinel layers on many of the LTO-modified LNMO facets, with a thickness varying from about 1 to 10 nm. The surface modification in the form of amorphous islands was mostly possible on high-energy crystal facets. Physicochemical observations were used to propose a molecular mechanism for the surface modification, combining insights from metalorganic chemistry with the crystallographic properties of LNMO. The improvements in functional properties were investigated in half cells. The cell impedance increased faster for the bare LNMO compared to amorphous LTO modified LNMO, resulting in R-ct values as high as 1247 Omega (after 1000 cycles) for bare LNMO, against 216 Omega for the modified material. At 10C, the modified material boosted a 15% increase in average discharge capacity. The improvements in electrochemical performance were attributed to the increase in electrochemically active surface area, as well as to improved HF-scavenging, resulting in the formation of protective byproducts, generating a more stable interface during prolonged cycling.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	001102666700001	Publication Date	2023-11-09
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2046-2069	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	3.9	Times cited		Open Access
Notes				Approved	Most recent IF: 3.9; 2023 IF: 3.108
Call Number	UA @ admin @ c:irua:202091			Serial	9096
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Author	Batuk, M.; Vandemeulebroucke, D.; Ceretti, M.; Paulus, W.; Hadermann, J.
Title	Topotactic redox cycling in SrFeO2.5+δ explored by 3D electron diffraction in different gas atmospheres			Type	A1 Journal article
Year	2022	Publication	Journal of materials chemistry A : materials for energy and sustainability	Abbreviated Journal	J Mater Chem A
Volume		Issue		Pages
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	For oxygen conducting materials applied in solid oxide fuel cells and chemical-looping processes, the understanding of the oxygen diffusion mechanism and the materials’ crystal structure at different stages of the redox reactions is a key parameter to control their performance. In this paper we report the first ever in situ 3D ED experiment in a gas environment and with it uncover the structure evolution of SrFeO2.5 as notably different from that reported from in situ X-ray and in situ neutron powder diffraction studies in gas environments. Using in situ 3D ED on submicron sized single crystals obtained from a high quality monodomain SrFeO2.5 single crystal , we observe the transformation under O2 flow of SrFeO2.5 with an intra- and interlayer ordering of the left and right twisted (FeO4) tetrahedral chains (space group Pcmb) into consecutively SrFeO2.75 with space group Cmmm (at 350°C, 33% O2) and SrFeO3-δ with space group Pm3 ̅m (at 400°C, 100% O2). Upon reduction in H2 flow, the crystals return to the brownmillerite structure with intralayer order, but without regaining the interlayer order of the pristine crystals. Therefore, redox cycling of SrFeO2.5 crystals in O2 and H2 introduces stacking faults into the structure, resulting in an I2/m(0βγ)0s symmetry with variable β.
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Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000891928400001	Publication Date	0000-00-00
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2050-7488	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	11.9	Times cited		Open Access	OpenAccess
Notes	Financial support is acknowledged from the FWO-Hercules fund I003218N ‘Infrastructure for imaging nanoscale processes in gas/vapor or liquid environments’, from the University of Antwerp through grant BOF TOP 38689. This work was supported by the European Commission Horizon 2020 NanED grant number 956099. Financial support from the French National Research Agency (ANR) through the project “Structural induced Electronic Complexity controlled by low temperature Topotactic Reaction” (SECTOR No. ANR-14-CE36- 0006-01) is gratefully acknowledged.			Approved	Most recent IF: 11.9
Call Number	EMAT @ emat @c:irua:192325			Serial	7229
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Author	Mallick, S.; Zhang, W.; Batuk, M.; Gibbs, A.S.; Hadermann, J.; Halasyamani, P.S.; Hayward, M.A.
Title	The crystal and defect structures of polar KBiNb₂O₇			Type	A1 Journal article
Year	2022	Publication	Journal of the Chemical Society : Dalton transactions	Abbreviated Journal	Dalton T
Volume	51	Issue	5	Pages	1866-1873
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	KBiNb2O7 was prepared from RbBiNb2O7 by a sequence of cation exchange reactions which first convert RbBiNb2O7 to LiBiNb2O7, before KBiNb2O7 is formed by a further K-for-Li cation exchange. A combination of neutron, synchrotron X-ray and electron diffraction data reveal that KBiNb2O7 adopts a polar, layered, perovskite structure (space group A11m) in which the BiNb2O7 layers are stacked in a (0, ½, z) arrangement, with the K+ cations located in half of the available 10-coordinate interlayer cation sites. The inversion symmetry of the phase is broken by a large displacement of the Bi3+ cations parallel to the y-axis. HAADF-STEM images reveal that KBiNb2O7 exhibits frequent stacking faults which convert the (0. ½, z) layer stacking to (½, 0, z) stacking and vice versa, essentially switching the x- and y-axes of the material. By fitting the complex diffraction peak shape of the SXRD data collected from KBiNb2O7 it is estimated that each layer has approximately an ~11% chance of being defective – a high level which is attributed to the lack of cooperative NbO6 tilting in the material, which limits the lattice strain associated with each fault.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000741540300001	Publication Date	2022-01-05
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1477-9226	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	4	Times cited		Open Access	OpenAccess
Notes	Experiments at the Diamond Light Source were performed as part of the Block Allocation Group award “Oxford/Warwick Solid State Chemistry BAG to probe composition-structure-property relationships in solids” (EE18786). Experiments at the ISIS pulsed neutron facility were supported by a beam time allocation from the STFC (RB 2000148). SM thanks Somerville College for an Oxford Ryniker Lloyd scholarship. PSH and WZ thank the National Science Foundation (DMR-2002319) for support.			Approved	Most recent IF: 4
Call Number	EMAT @ emat @c:irua:185504			Serial	6951
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