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“3D FIB/SEM study of Ni4Ti3 precipitates in Ni-Ti alloys with different thermal-mechanical histories”. Cao S, Nishida M, Somsen C, Eggeler G, Schryvers D, , 02004 (2009). http://doi.org/10.1051/esomat/200902004
Abstract: The three-dimensional size, morphology and distribution of Ni4Ti3 precipitates growing in binary Ni-rich Ni-Ti alloys have been investigated via a slice view procedure in a Dual-Beam FIB/SEM system, in order to better stress-free Ni50.8Ti49.2 alloy with all four variants of precipitates and a compressed Ni51Ti49 alloy with aligned precipitates in one family were studied. The Ni4Ti3 precipitates reach a volume fraction of 9.6% in the reconstructed region of the stress-free alloy and 4.3% in the compressed one. In both cases, the mean volume, specific surface area, sphericity and aspect ratio of the precipitates are calculated and the Pair Distribution Functions of the precipitates are obtained. It is shown that most precipitates in the stress-free sample grow larger and have a more lenticular shape, while those in the compressed sample are more cylindrical. Deviations from these ideal shapes reveal internal steps in the stress-free sample and lamellae formation in the compressed one.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1051/esomat/200902004
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“3D reconstruction of a Ni51Ti49 alloy with precipitates by FIB-SEM alice-and-view”. Cao S, Tirry W, Schryvers D, Materia Japan 46, 803 (2007)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT)
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“3D reconstruction of Ni4Ti3 precipitates in a Ni51Ti49 alloy in a FIB/SEM dual-beam system”. Cao S, Tirry W, van den Broek W, Schryvers D, Materials science forum 583, 277 (2008). http://doi.org/10.4028/www.scientific.net/MSF.583.277
Abstract: Ni4Ti3 precipitates play an important role in the shape memory and superelastic behaviour of thermo-mechanically treated Ni-Ti material. The 3D morphology and distribution of such precipitates with lenticular shape and rhombohedral atomic structure in the austenitic B2 matrix of a binary Ni-rich Ni-Ti alloy has been elucidated via a slice view procedure in a Dual-Beam FIB/SEM system. With the sequence of cross-section SE images obtained from the SEM, a 3D reconstruction has been achieved after proper alignment and image processing, from which both qualitative and quantitative analysis can be performed. Careful imaging is needed to ensure that all variants of the precipitates are observed with equal probability, regardless sample orientation. Moreover, due to the weak contrast of the precipitates, proper imaging conditions need to be selected to allow for semi-automated image treatment. Finally, a volume ratio of 10.2% for the Ni4Ti3 precipitates could be calculated, summed over all variants, which yields a net composition of Ni50.36Ti49.64 for the matrix, leading to an increase of 113 degrees for the martensitic start temperature Ms. Also, the expected relative orientation of the different variants of the precipitates could be confirmed. In the near future, other quantitative measures on the distribution of the precipitates can be expected.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
DOI: 10.4028/www.scientific.net/MSF.583.277
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“3D strain fields surrounding Ni4Ti3: direct measurement and correlation with the R-phase”. Tirry W, Schryvers D, , 02032 (2009). http://doi.org/10.1051/esomat/200902032
Abstract: Strain fields introduced by coherent Ni4Ti3 precipitates in austenitic Ni-Ti are believed to be a possible origin of why the R-phase transformation is introduced as an extra step before transforming to the B19'. The presence of this strain field was already confirmed in the past by conventional transmission electron microscopy (TEM) techniques and measured quantitatively by high resolution TEM (HRTEM). This time the geometrical phase method is applied on HRTEM micrographs to measure the full 3D strain tensor of the strain fields. Since each atomic resolution micrograph only results in a 2D measurement of the strain, observations in two different zone orientations are combined to retrieve the 3 x 3 strain tensor. In this work observations in a [1-1 1](B2) and [1 0-1](B2) zone orientation are used and this in case of precipitates with a diameter of around 50nm. In a next step the measured strain tensor is compared to the calculated eigenstrain of the R-phase in reference to the B2 matrix. This comparison shows that the introduced strain is very similar to the eigenstrain of one R-phase variant. Since for both structures, Ni4Ti3 and R-phase, four orientation variants are possible, each variant of the R-phase is thus able to accommodate the strain field of one of the Ni4Ti3 variants.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
DOI: 10.1051/esomat/200902032
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“65th birthdays of W. Owen Saxton, David J. Smith and Dirk Van Dyck / PICO 2013 From multislice to big bang”. Lichte H, Dunin-Borkowski R, Tillmann K, Van Aert S, Van Tendeloo G Amsterdam (2013).
Keywords: ME3 Book as editor; Electron microscopy for materials research (EMAT)
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“Ab initio based atomic scattering amplitudes and {002} electron structure factors of InxGa1-xAs/GaAs quantum wells”. Titantah JT, Lamoen D, Schowalter M, Rosenauer A, Journal of physics : conference series 209, 012040 (2010). http://doi.org/10.1088/1742-6596/209/1/012040
Abstract: The atomic scattering amplitudes of the various atoms of the systems Ga1−xInxAs, GaAs1−xNx and InAs1−xNx are calculated using the density functional theory (DFT) approach. The scattering amplitudes of N, Ga, As and In in the model systems are compared with the frequently used Doyle and Turner values. Deviation from the latter values is found for small scattering vectors (s<0.3Å−1) and for these scattering vectors dependence on the orientation of the scattering vector and the chemical environment is reported. We suggest a parametrization of these modified scattering amplitudes (MASAs) for small scattering vectors (s<1.0Å−1). The MASAs are exploited within zero pressure classical Metropolis Monte Carlo (MC), finite temperature calculations to investigate the effect of quantum well size on the electron {002} structure factor (SF) of Ga1−xInxAs quantum wells.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1088/1742-6596/209/1/012040
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“Ab initio computation of the mean inner Coulomb potential of technological important semiconductors”. Schowalter M, Rosenauer A, Lamoen D, Kruse P, Gerthsen D, 1007, 233 (2005)
Keywords: A1 Journal article; Electron Microscopy for Materials Science (EMAT);
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“Accurate description of the van der Waals interaction of an electron-positron pair with the surface of a topological insulator”. Saniz R, Vercauteren S, Lamoen D, Partoens B, Barbiellini B, Journal of physics : conference series 505, 012002 (2014). http://doi.org/10.1088/1742-6596/505/1/012002
Abstract: Positrons can be trapped in localized states at the surface of a material, and thus quite selectively interact with core or valence surface electrons. Hence, advanced surface positron spectroscopy techniques can present the ideal tools to study a topological insulator, where surface states play a fundamental role. We analyze the problem of a positron at a TI surface, assuming that it is a weakly physisorbed positronium (Ps) atom. To determine if the surface of interest in a material can sustain such a physisorption, an accurate description of the underlying van der Waals (vdW) interaction is essential. We have developed a first-principles parameterfree method, based on the density functional theory, to extract key parameters determining the vdW interaction potential between a Ps atom and the surface of a given material. The method has been successfully applied to quartz and preliminary results on Bi2Te2Se indicate the existence of a positron surface state. We discuss the robustness of our predictions versus the most relevant approximations involved in our approach.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Times cited: 2
DOI: 10.1088/1742-6596/505/1/012002
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“Accurate measurements of atomic displacements in La0.9Sr0.1MnO3 thin films grown on a SrTiO3 substrate”. Geuens P, Lebedev OI, van Dyck D, Van Tendeloo G s.l., page 1133 (2000).
Keywords: H3 Book chapter; Electron microscopy for materials research (EMAT); Vision lab
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Lobato I (2014) Accurate modeling of high angle electron scattering. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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Amin-Ahmadi B (2015) Adanced TEM investigation of the elementary plsticity mechanisms in palladium thin films at the nano scale. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“Advanced electron microscopy and its possibilities to solve complex structures: application to transition metal oxides”. Van Tendeloo G, Hadermann J, Abakumov AM, Antipov EV, Journal of materials chemistry 19, 2660 (2009). http://doi.org/10.1039/b817914j
Abstract: Design and optimization of materials properties can only be performed through a thorough knowledge of the structure of the compound. In this feature article we illustrate the possibilities of advanced electron microscopy in materials science and solid state chemistry. The different techniques are briefly discussed and several examples are given where the structures of complex oxides, often with a modulated structure, have been solved using electron microscopy.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 9
DOI: 10.1039/b817914j
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“Advanced electron microscopy characterisation of important precipitation and ordering phenomena in shape memory systems”. Schryvers D, Shape memory and superelasticity 1, 78 (2015). http://doi.org/10.1007/s40830-015-0006-3
Abstract: The present paper discusses some important aspects of precipitation and ordering in alloy systems that show a martensitic transformation and can or are used as shape memory or superelastic metallic systems. The precipitates are investigated by a variety of conventional and advanced electron microscopy techniques, including atomic resolution, 3D slice-and-view, energy loss spectroscopy etc. Depending on the system, such secondary phases can decrease the probability of a displacive transformation by changing the phase stability in the system, such as in the case of NiAl or NiTiPd, or can mechanically hinder the passage of the transformation interface, as in NiTiNb. On the other hand, properly controlling the nucleation and growth of some precipitates can strongly improve the properties of some types of materials, as is the case for the well-known Ni4Ti3 precipitates.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1007/s40830-015-0006-3
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Goris B (2014) Advanced electron tomography : 3 dimensional structural characterisation of nanomaterials down to the atomic scale. Antwerpen
Keywords: Doctoral thesis; Electron microscopy for materials research (EMAT)
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“Advanced TEM and SEM methods applied to 3D nano- and microstructural investigations of Ni4Ti3 precipitates in Ni-Ti (SMA)”. Schryvers D, Tirry W, Cao S, Diffusion and defect data : solid state data : part B : solid state phenomena 172/174, 229 (2011). http://doi.org/10.4028/www.scientific.net/SSP.172-174.229
Abstract: Two different kinds of experimental approaches yielding three-dimensional structural information on metastable semi-coherent precipitates are demonstrated. By combining high-resolution images from two independent viewing directions a full description of the strain field surrounding a nano-sized Ni4Ti3 precipitate in Ni-Ti can be obtained. The principal axes and strains correlate well with the transformation strain of the observed R-phase transformation close to the precipitate. Using a slice-and-view procedure in a FIB/SEM dual-beam instrument, a three-dimensional voxel dataset is produced from which morphological and distributional information on the same precipitates can be obtained yielding new insight into the particular transformation paths of these alloys, relevant for their functional behaviour.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.4028/www.scientific.net/SSP.172-174.229
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“Advanced TEM investigations on Ni-Ti shape memory material: strain and concentration gradients surrounding Ni4Ti3 precipitates”. Schryvers D, Tirry W, Yang Z, , 329 (2005)
Abstract: Lattice deformations and concentration gradients surrounding Ni4Ti3 precipitates grown by appropriate annealing in a Ni51Ti49 B2 austenite matrix are determined by a combination of TEM techniques. Quantitative Fourier analysis of HRTEM images reveals a deformed nanoscale region with lattice deformations up to 2% while EELS and EDX indicate a Ni depleted zone up to 150 nm away from the matrix-precipitate interface.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT)
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“Advanced TEM studies of martensite and related phase transformations”. Schryvers D s.l., page 947 (1999).
Keywords: H1 Book chapter; Electron microscopy for materials research (EMAT)
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“Aerosol synthesis of nanostructured, ultrafine fullerene particles”. Joutsensaari J, Ahonen PP, Tapper U, Kauppinen EI, Pauwels B, Amelinckx S, Van Tendeloo G, (1999)
Keywords: P3 Proceeding; Electron microscopy for materials research (EMAT)
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“Andreev-type states induced by quantum confinement”. Shanenko AA, Croitoru MD, Mints RG, Peeters FM, Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques 2, 611 (2008). http://doi.org/10.1134/S1027451008040216
Abstract: The properties of a clean superconductor with nanoscale dimensions are governed by quantum confinement of the electrons. This results in a spatially inhomogeneous superconducting condensate and in the formation of new Andreev-type quasiparticle states. These states are mainly located beyond regions where the superconducting condensate is enhanced. A numerical self-consistent solution of the Bogoliubov-de Gennes equations for a cylindrical metallic nanowire shows that these new Andreev-type states decrease the ratio of the energy gap to the critical temperature.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1134/S1027451008040216
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“Anion ordering in fluorinated La2CuO4”. Hadermann J, Abakumov AM, Van Tendeloo G, Shpanchenko RV, Oleinikov PN, Antipov EV s.l., page 133 (1999).
Keywords: H1 Book chapter; Electron microscopy for materials research (EMAT)
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“The application of transmission electron microscopy (TEM) in the research of inorganic colorants in stained glass windows and parchment illustrations”. Fredrickx P, Wouters J, Schryvers D Archetype, London, page 137 (2003).
Keywords: H3 Book chapter; Electron microscopy for materials research (EMAT)
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“Aqueous CSD approach for the growth of novel, lattice-tuned LaxCe1-xO\delta epitaxial layers”. Narayanan V, Lommens P, De Buysser K, Vanpoucke DEP, Huehne R, Molina L, Van Tendeloo G, van der Voort P, Van Driessche I, Journal of materials chemistry 22, 8476 (2012). http://doi.org/10.1039/c2jm15752g
Abstract: Lanthanumcerium oxide (LCO) films were deposited on Ni-5%W substrates by chemical solution deposition (CSD) from water-based precursors. LCO films containing different ratios of lanthanum and cerium ions (from CeO2 to La2Ce2O7) were prepared. The composition of the layers was optimized towards the formation of LCO buffer layers, lattice-matched with the superconducting YBa2Cu3Oy layer, useful for the development of coated conductors. Single, crack-free LCO layers with a thickness of up to 140 nm could be obtained in a single deposition step. The crystallinity and microstructure of these lattice-matched LCO layers were studied by X-ray diffraction techniques, RHEED and SEM. We find that only layers with thickness below 100 nm show a crystalline top surface although both thick and thin layers show good biaxial texture in XRD. On the most promising layers, AFM and (S)TEM were performed to further evaluate their morphology. The overall surface roughness varies between 3.9 and 7.5 nm, while the layers appear much more dense than the frequently used La2Zr2O7 (LZO) systems, showing much smaller nanovoids (12 nm) than the latter system. Their effective buffer layer action was studied using XPS. The thin LCO layers supported the growth of superconducting YBCO deposited using PLD methods.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 24
DOI: 10.1039/c2jm15752g
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Van Aert S (2011) Atomen in 3D : Antwerpenaren brengen atomaire structuur nanodeeltjes in beeld. 9
Keywords: Newspaper/Magazine/blog article; Electron microscopy for materials research (EMAT)
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“Atomen tellen”. Van Aert S, Batenburg J, Van Tendeloo S, Nederlands tijdschrift voor natuurkunde (1991) 77, 292 (2011)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT); Vision lab
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“Atomic scale characterization of supported and assembled nanoparticles”. Pauwels B, Yandouzi M, Schryvers D, Van Tendeloo G, Verschoren G, Lievens P, Hou M, van Swygenhoven H, , B8.3 (2001)
Keywords: P3 Proceeding; Electron microscopy for materials research (EMAT)
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“Atomic scale modeling of supported and assembled nanoparticles”. Zhurkin E, Hou M, van Swygenhoven H, Pauwels B, Yandouzi M, Schryvers D, Van Tendeloo G, Lievens P, Verschoren G, Kuriplach J, van Peteghem S, Segers D, Dauwe C, , B8.2 (2001)
Keywords: P3 Proceeding; Electron microscopy for materials research (EMAT)
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“Atomic structure of alloys close to phase transitions”. Van Tendeloo G, Schryvers D, Nucleation and growth processes in materials 580, 283 (2000)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Biaxially aligned yttria stabilized zirconia and titanium nitride layers deposited by unbalanced magnetron sputtering”. Mahieu S, Ghekiere P, de Winter G, de Gryse R, Depla D, Lebedev OI, Diffusion and defect data : solid state data : part B : solid state phenomena
T2 –, 2nd International Conference on Texture and Anisotropy of Polycrystals, JUL 07-09, 2004, Metz, FRANCE 105, 447 (2005)
Abstract: Control of the texture and the biaxial alignment of sputter deposited films has provoked a great deal of interest due to its technological importance. indeed, many physical properties of thin films are influenced by the biaxial alignment. In this context, extensive research has been established to understand the growth mechanism of biaxially aligned Yttria Stabilized Zirconia (YSZ) as a buffer layer for high temperature superconducting copper oxides. In this work, the growth mechanism in general and the mechanism responsible of the biaxial alignment in detail were investigated for thin films of YSZ and TiN deposited by unbalanced magnetron sputtering using non-aligned polycrystalline stainless steel substrates. The mechanism responsible for the preferential out-of-plane alignment has been investigated by performing depositions on a non-tilted substrate. However, to study the in-plane alignment a tilted substrate was used. The microstructure of the deposited layers was characterised by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The crystallographic alignment has been investigated by X-ray diffraction (XRD) (angular scans and pole figures) and by Selective Area Diffraction (SAD). It was observed that the deposited layers show a zone T or zone II structure and the layers with a zone T structure consist of faceted grains. There seems to be a correlation between the crystal habit of these faceted grains and the measured biaxial alignment. A model for the preferential out-of-plane orientation, the in-plane alignment and the correlation between the microstructure and the biaxial alignment is proposed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Calculation of Debye-Waller temperature factors for GaAs”. Schowalter M, Rosenauer A, Titantah JT, Lamoen D, Springer proceedings in physics 120, 195 (2008)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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“Catalyst traces after chemical purification in CVD grown carbon nanotubes”. Biró, LP, Khanh NQ, Horváth ZE, Vértesy Z, Kocsonya A, Konya Z, Osváth Z, Koós A, Guylai J, Zhang XB, Van Tendeloo G, Fonseca A, Nagy JB, , 183 (2001)
Keywords: P3 Proceeding; Electron microscopy for materials research (EMAT)
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