“Microstructure of quenched Ni-rich Ni-Ti shape memory alloys”. Somsen C, Kästner J, Wassermann EF, Boullay P, Schryvers D, Journal de physique: 4
T2 –, 8th European Symposium on Martensitic Transformations (ESOMAT2000), SEP 04-08, 2000, COMO, ITALY 11, 445 (2001). http://doi.org/10.1051/jp4:2001874
Abstract: Microstructural investigations with transmission electron microscopy were carried out on quenched Ni-Ti alloys with 52 and 54.5 at% Ni. For the Ni52Ti48 specimen long time exposed diffraction patterns of a single grain show besides the expected reflections of the B2-phase, two sets of extra reflections in different zones. The first type of spots is explained by lattice displacement waves, which are regarded as precursors of the martensitic Ni-Ti phases, B 19' and R-phase, respectively. The second set of reflection with more diffuse intensity than the other reflections is related to Ni4Ti3 precipitates in an early state of formation. For the Ni-richer Ni54.5Ti45.5 alloy only Ni4Ti3 precipitates in an early state of formation are found but no precursors of the B 19'- and R-phase.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1051/jp4:2001874
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“Nanoscale inhomogeneities in melt-spun Ni-Al”. Potapov P, Ochin P, Pons J, Schryvers D, Journal de physique: 4 11, 439 (2001). http://doi.org/10.1051/jp4:2001873
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1051/jp4:2001873
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“Structural characterisation of melt-spun Ti-Ni-Cu-ribbons”. Schryvers D, Potapov P, Ledda A, Shelyakov A, Journal de physique: 4 11, 363 (2001). http://doi.org/10.1051/jp4:2001861
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1051/jp4:2001861
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“Recent Advances in Transmission Electron Microscopy for Materials Science at the EMAT Lab of the University of Antwerp”. 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, Materials 11, 1304 (2018). http://doi.org/10.3390/ma11081304
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.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.654
Times cited: 15
DOI: 10.3390/ma11081304
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“Unravelling the multi-scale structure-property relationship of laser powder bed fusion processed and heat-treated AlSi10Mg”. Van Cauwenbergh P, Samaee V, Thijs L, Nejezchlebova J, Sedlak P, Ivekovic A, Schryvers D, Van Hooreweder B, Vanmeensel K, Scientific Reports 11, 6423 (2021). http://doi.org/10.1038/S41598-021-85047-2
Abstract: Tailoring heat treatments for Laser Powder Bed Fusion (LPBF) processed materials is critical to ensure superior and repeatable material properties for high-end applications. This tailoring requires in-depth understanding of the LPBF-processed material. Therefore, the current study aims at unravelling the threefold interrelationship between the process (LPBF and heat treatment), the microstructure at different scales (macro-, meso-, micro-, and nano-scale), and the macroscopic material properties of AlSi10Mg. A similar solidification trajectory applies at different length scales when comparing the solidification of AlSi10Mg, ranging from mould-casting to rapid solidification (LPBF). The similarity in solidification trajectories triggers the reason why the Brody-Flemings cellular microsegregation solidification model could predict the cellular morphology of the LPBF as-printed microstructure. Where rapid solidification occurs at a much finer scale, the LPBF microstructure exhibits a significant grain refinement and a high degree of silicon (Si) supersaturation. This study has identified the grain refinement and Si supersaturation as critical assets of the as-printed microstructure, playing a vital role in achieving superior mechanical and thermal properties during heat treatment. Next, an electrical conductivity model could accurately predict the Si solute concentration in LPBF-processed and heat-treated AlSi10Mg and allows understanding the microstructural evolution during heat treatment. The LPBF-processed and heat-treated AlSi10Mg conditions (as-built (AB), direct-aged (DA), stress-relieved (SR), preheated (PH)) show an interesting range of superior mechanical properties (tensile strength: 300-450 MPa, elongation: 4-13%) compared to the mould-cast T6 reference condition.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.259
DOI: 10.1038/S41598-021-85047-2
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“High resolution transmission electron microscopy study of nanoscale Ni-rich Ni-Al films evaporated onto NaCl and KCl”. Yandouzi M, Toth L, Schryvers D, Nanostructured materials 10, 99 (1998). http://doi.org/10.1016/S0965-9773(98)00025-7
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1016/S0965-9773(98)00025-7
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“La microscopie électronique à, transmission (MET) et son utilisation dans l'étude d'inclusions nano-cristallines dans le verre”. Fredrickx P, Schryvers D, L'archéométrie au service des monuments et des oeuvres d'art 10, 131 (2002)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT)
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“Ni cluster formation in low temperature annealed Ni50.6Ti49.4”. Pourbabak S, Wang X, Van Dyck D, Verlinden B, Schryvers D, Functional materials letters 10, 1740005 (2017). http://doi.org/10.1142/S1793604717400057
Abstract: Various low temperature treatments of Ni50.6Ti49.4 have shown an unexpected effect on the martensitic start temperature. Periodic diffuse intensity distributions in reciprocal space indicate the formation of short pure Ni strings along the <111> directions in the B2 ordered lattice, precursing the formation of Ni4Ti3 precipitates formed at higher annealing temperatures.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.234
Times cited: 4
DOI: 10.1142/S1793604717400057
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“Phase transformations and precipitation in amorphous Ti50Ni25Cu25 ribbons”. Satto C, Ledda A, Potapov P, Janssens JF, Schryvers D, Intermetallics 9, 395 (2001). http://doi.org/10.1016/S0966-9795(01)00015-2
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.14
Times cited: 16
DOI: 10.1016/S0966-9795(01)00015-2
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“Atomic-scale viscoplasticity mechanisms revealed in high ductility metallic glass films”. Idrissi H, Ghidelli M, Béché, A, Turner S, Gravier S, Blandin J-J, Raskin J-P, Schryvers D, Pardoen T, Scientific reports 9, 13426 (2019). http://doi.org/10.1038/s41598-019-49910-7
Abstract: The fundamental plasticity mechanisms in thin freestanding Zr65Ni35 metallic glass films are investigated in order to unravel the origin of an outstanding strength/ductility balance. The deformation process is homogenous until fracture with no evidence of catastrophic shear banding. The creep/relaxation behaviour of the films was characterized by on-chip tensile testing, revealing an activation volume in the range 100–200 Å3. Advanced high-resolution transmission electron microscopy imaging and spectroscopy exhibit a very fine glassy nanostructure with well-defined dense Ni-rich clusters embedded in Zr-rich clusters of lower atomic density and a ~2–3 nm characteristic length scale. Nanobeam electron diffraction analysis reveals that the accumulation of plastic deformation at roomtemperature
correlates with monotonously increasing disruption of the local atomic order. These results provide experimental evidences of the dynamics of shear transformation zones activation in metallic glasses. The impact of the nanoscale structural heterogeneities on the mechanical properties including the rate dependent behaviour is discussed, shedding new light on the governing plasticity mechanisms in metallic glasses with initially heterogeneous atomic arrangement.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.259
DOI: 10.1038/s41598-019-49910-7
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“Linking a completely three-dimensional nanostrain to a structural transformation eigenstrain”. Tirry W, Schryvers D, Nature materials 8, 752 (2009). http://doi.org/10.1038/NMAT2488
Abstract: NiTi is one of the most popular shape-memory alloys, a phenomenon resulting from a martensitic transformation. Commercial NiTi-based alloys are often thermally treated to contain Ni4Ti3 precipitates. The presence of these precipitates can introduce an extra transformation step related to the so-called R-phase. It is believed that the strain field surrounding the precipitates, caused by the matrixprecipitate lattice mismatch, lies at the origin of this intermediate transformation step. Atomic-resolution transmission electron microscopy in combination with geometrical phase analysis is used to measure the elastic strain field surrounding these precipitates. By combining measurements from two different crystallographic directions, the three-dimensional strain matrix is determined from two-dimensional measurements. Comparison of the measured strain matrix to the eigenstrain of the R-phase shows that both are very similar and that the introduction of the R-phase might indeed compensate the elastic strain introduced by the precipitate.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 39.737
Times cited: 53
DOI: 10.1038/NMAT2488
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“Dislocation driven nanosample plasticity: new insights from quantitative in-situ TEM tensile testing”. Samaee V, Gatti R, Devincre B, Pardoen T, Schryvers D, Idrissi H, Scientific Reports 8, 12012 (2018). http://doi.org/10.1038/s41598-018-30639-8
Abstract: Intrinsic dislocation mechanisms in the vicinity of free surfaces of an almost FIB damage-free single crystal Ni sample have been quantitatively investigated owing to a novel sample preparation method combining twin-jet electro-polishing, in-situ TEM heating and FIB. The results reveal that the small-scale plasticity is mainly controlled by the conversion of few tangled dislocations, still present after heating, into stable single arm sources (SASs) as well as by the successive operation of these sources. Strain hardening resulting from the operation of an individual SAS is reported and attributed to the decrease of the length of the source. Moreover, the impact of the shortening of the dislocation source on the intermittent plastic flow, characteristic of SASs, is discussed. These findings provide essential information for the understanding of the regime of ‘dislocation source’ controlled plasticity and the related mechanical size effect.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 4.259
Times cited: 9
DOI: 10.1038/s41598-018-30639-8
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“Stability of Ni in nitinol oxide surfaces”. Tian H, Schryvers D, Liu D, Jiang Q, van Humbeeck J, Acta biomaterialia 7, 892 (2011). http://doi.org/10.1016/j.actbio.2010.09.009
Abstract: The stability of Ni in titanium oxide surface layers on nitinol wires known to release certain amounts of Ni was investigated by first principles density functional theory and transmission electron microscopy. The oxides were identified as a combination of TiO and TiO2 depending on the thickness of the layer. The calculations indicate that free Ni atoms can exist in TiO at ambient temperature while Ni particles form in TiO2, which was confirmed by the transmission electron microscopy observations. The results are discussed with respect to surface stability and Ni release due to free Ni atoms and Ni particles.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.319
Times cited: 39
DOI: 10.1016/j.actbio.2010.09.009
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“Electronically decoupled stacking fault tetrahedra embedded in Au(111) films”. Schouteden K, Amin-Ahmadi B, Li Z, Muzychenko D, Schryvers D, Van Haesendonck C, Nature communications 7, 14001 (2016). http://doi.org/10.1038/ncomms14001
Abstract: Stacking faults are known as defective structures in crystalline materials that typically lower the structural quality of the material. Here, we show that a particular type of defects, i.e., stacking fault tetrahedra (SFTs), exhibits quantized, particle-in-a-box electronic behaviour, revealing a potential synthetic route to decoupled nanoparticles in metal films. We report on the electronic properties of SFTs that exist in Au(111) films, as evidenced by scanning tunnelling microscopy and confirmed by transmission electron microscopy. We find that the SFTs reveal a remarkable decoupling from their metal surroundings, leading to pronounced energy level quantization effects within the SFTs. The electronic behaviour of the SFTs can be described well by the particle-in-a-box model. Our findings demonstrate that controlled preparation of SFTs may offer an alternative way to achieve well decoupled nanoparticles of high crystalline quality in metal thin films without the need of thin insulating layers.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 7
DOI: 10.1038/ncomms14001
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“On the nucleation mechanism of {112} <, 111 >, mechanical twins in as-quenched beta metastable Ti-12 wt.% Mo alloy”. Marteleur M, Idrissi H, Amin-Ahmadi B, Prima F, Schryvers D, Jacques PJ, Materialia 7, Unsp 100418 (2019). http://doi.org/10.1016/J.MTLA.2019.100418
Abstract: Recently developed beta-metastable Ti grades take advantage of the simultaneous activation of TRIP and TWIP effects for enhancing their work hardening rate. However, the role of each plasticity mechanism on the macroscopic mechanical response is still unclear. In this work, the nucleation mechanism of the first activated plasticity mechanism, namely {112} < 111 > twinning, was investigated. Firstly, post-mortem TEM analysis showed that twins nucleate on pre-existing microstructural defects such as thermal jogs with the zonal dislocation mechanism. The precipitation of the omega phase on twin boundaries has been observed, as well as the emission of numerous dislocations from super-jogs present in these twin boundaries. It is also shown that {112} < 111 > twins act as effective dislocation sources for the subsequent plasticity mechanisms such as beta -> alpha '' martensitic transformation and {332} < 111 > twinning. Secondly, in situ TEM tensile testing of the investigated Ti grade highlighted the primary role of the initial defect configuration present in the microstructure. It is shown that twins cannot nucleate without the presence of specific defects allowing the triggering of the dislocation decomposition needed for the twinning mechanism highlighted in investigated bulk samples.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1016/J.MTLA.2019.100418
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“Austenite and martensite microstructures in splat-cooled Ni-Al”. Schryvers D, Holland-Moritz D, Intermetallics 6, 427 (1998). http://doi.org/10.1016/S0966-9795(97)00091-5
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.14
Times cited: 13
DOI: 10.1016/S0966-9795(97)00091-5
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“Dislocation-mediated relaxation in nanograined columnar palladium films revealed by on-chip time-resolved HRTEM testing”. Colla M-S, Amin-Ahmadi B, Idrissi H, Malet L, Godet S, Raskin J-P, Schryvers D, Pardoen T, Nature communications 6, 5922 (2015). http://doi.org/10.1038/ncomms6922
Abstract: The high-rate sensitivity of nanostructured metallic materials demonstrated in the recent literature is related to the predominance of thermally activated deformation mechanisms favoured by a large density of internal interfaces. Here we report time-resolved high-resolution electron transmission microscopy creep tests on thin nanograined films using on-chip nanomechanical testing. Tests are performed on palladium, which exhibited unexpectedly large creep rates at room temperature. Despite the small 30-nm grain size, relaxation is found to be mediated by dislocation mechanisms. The dislocations interact with the growth nanotwins present in the grains, leading to a loss of coherency of twin boundaries. The density of stored dislocations first increases with applied deformation, and then decreases with time to drive additional deformation while no grain boundary mechanism is observed. This fast relaxation constitutes a key issue in the development of various micro- and nanotechnologies such as palladium membranes for hydrogen applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
Times cited: 34
DOI: 10.1038/ncomms6922
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“Recrystallization and grain growth in a B2 iron aluminide alloy”. Samajdar I, Ratchev P, Verlinden B, Schryvers D, Intermetallics 6, 419 (1998). http://doi.org/10.1016/S0966-9795(97)00092-7
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.14
Times cited: 17
DOI: 10.1016/S0966-9795(97)00092-7
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“Towards biolubricant compatible vegetable oils by pore mouth hydrogenation with shape-selective Pt/ZSM-5 catalysts”. Van Aelst J, Philippaerts A, Bartholomeeusen E, Fayad E, Thibault-Starzyk F, Lu J, Schryvers D, Ooms R, Verboekend D, Jacobs P, Sels B, Catalysis science &, technology 6, 2820 (2016). http://doi.org/10.1039/C6CY00498A
Abstract: Pt/ZSM-5 catalysts with various crystal sizes were prepared via competitive ion-exchange, followed by a slow activation procedure. Even when using very large ZSM-5 crystals, highly dispersed Pt nano-clusters were contained within the zeolite crystal's voids, as ascertained by 2D pressure-jump IR spectroscopy of adsorbed CO and focussed ion-beam transmission electron microscopy. The shape-selective properties of the Pt/ZSM-5 catalysts were evaluated in the partial hydrogenation of soybean oil. Unique hydrogenation selectivities were observed, as the fatty acids located at the central position of the triacylglycerol (TAG) molecules were preferentially hydrogenated. The resulting oil has therefore high levels of intermediately melting TAGs, which are compatible with biolubricants due to their improved oxidative stability and still appropriate low-temperature fluidity. The TAG distribution in the partially hydrogenated soybean oil samples was independent from the zeolite crystal size, while the hydrogenation activity linearly increases with the crystal's external surface area. This trend was confirmed with a Pt loaded mesoporous ZSM-5 zeolite, obtained via a mild alkaline treatment. These observations imply and confirm a genuine pore mouth catalysis mechanism, in which only one fatty acid chain of the TAG is able to enter the micropores of ZSM-5, where the double bonds are hydrogenated by the crystal encapsulated Pt-clusters.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 5.773
Times cited: 5
DOI: 10.1039/C6CY00498A
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“Defect structures in CuZr martensite, studies by CTEM and HRTEM”. Seo JW, Schryvers D, Journal de physique: 4 C5, 149 (1997). http://doi.org/10.1051/jp4:1997523
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 1
DOI: 10.1051/jp4:1997523
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“Electron microscopy studies of martensite microstructures”. Schryvers D, Journal de physique: 4 C5, 109 (1997). http://doi.org/10.1051/jp4:1997517
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1051/jp4:1997517
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“HRTEM study of austenite and martensite in splat-cooled and nanoscale thin film Ni-Al”. Schryvers D, Yandouzi M, Holland-Moritz D, Toth L, Journal de physique: 4 C5, 203 (1997). http://doi.org/10.1051/jp4:1997532
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1051/jp4:1997532
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“Martensitic and related transformations in Ni-Al alloys”. Schryvers D, Journal de physique: 4
T2 –, IIIrd European Symposium on Martensitic Transformations (ESOMAT 94), SEP 14-16, 1994, BARCELONA, SPAIN 5, 225 (1995). http://doi.org/10.1051/jp4:1995235
Abstract: The present paper gives a review of results of recent studies investigating the fundamentals of the martensitic and related phase transformations in Ni-Al. For the former case, the emphasis will be on the microstructure of martensite plates. The latter include the metastable Ni2Al omega-like and stable Ni5Al3 bainitic phases. These phases will be discussed in view of their atomic structure, nucleation, growth and effect on the martensitic transformation. A separate chapter will deal with precursor effects.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 21
DOI: 10.1051/jp4:1995235
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“Nucleation and growth of the Ni5Al3 phase in Ni-Al austenite and martensite”. Schryvers D, Toth L, Ma Y, Tanner L, Journal de physique: 4
T2 –, IIIrd European Symposium on Martensitic Transformations (ESOMAT 94), SEP 14-16, 1994, BARCELONA, SPAIN 5, 299 (1995). http://doi.org/10.1051/jp4:1995246
Abstract: The nucleation and growth mechanisms of Ni5Al3 precipitates and microtwinned plates in B2 austenite and 2M (3R) martensite phases are described on the basis of conventional and high resolution electron microscopy. In the Ni62.5Al37.5 B2 austenite matrix short annealings at 550 degrees C introduce three-pointed star shaped precipitates consisting of twin related parts of different variants of the Ni5Al3 structure. Longer annealings result in plates growing separately from these wings and developing microtwinning in order to accommodate stress built-up at the interfaces with the surrounding matrix. Annealing of Ni65Al35 2M martensite plates induces simple reordering into the Ni5Al3 phase, increasing the fct c/a ratio by about 1%. As a result stracking faults are introduced in the smallest twin variants.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 3
DOI: 10.1051/jp4:1995246
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“SAED and HREM results suggest a NiTi B19' based superstructure for CuZr martensite”. Schryvers D, Journal de physique: colloques, suppléments 5, 1047 (1995). http://doi.org/10.1051/jp4/1995581047
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 2
DOI: 10.1051/jp4/1995581047
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“Ni2Al versus Ni5Al3 ordering in Ni65Al35 austenite and martensite”. Schryvers D, Toth L, van Humbeeck J, Beyer J, Journal de physique: colloques, suppléments 5, 1029 (1995). http://doi.org/10.1051/jp4/1995581029
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Times cited: 12
DOI: 10.1051/jp4/1995581029
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“In-Situ TEM Stress Induced Martensitic Transformation in Ni50.8Ti49.2 Microwires”. Pourbabak S, Orekhov A, Samaee V, Verlinden B, Van Humbeeck J, Schryvers D, Shape memory and superelasticity 5, 154 (2019). http://doi.org/10.1007/s40830-019-00217-6
Abstract: In-situ transmission electron microscopy tensile straining is used to study the stress induced martensitic transformation in Ni50.8Ti49.2. Two microwire samples with different heat treatment are investigated from which one single crystal and three polycrystalline TEM specimens, the latter with micro- and nano-size grains, have been produced. The measured Young’s modulus for all TEM specimens is around 70 GPa, considerably higher than the averaged 55 GPa of the original microwire sample. The height of the superelastic stress plateau shows an inverse relationship with the specimen thickness for the polycrystalline specimens. Martensite starts nucleating within the elastic region of the stress–strain curve and on the edges of the specimens while also grain boundaries act as nucleation sites in the polycrystalline specimens. When a martensite plate reaches a grain boundary in the polycrystalline specimen, it initiates the transformation in the neighboring grain at the other side of the grain boundary. In later stages martensite plates coalesce at higher loads in the stress plateau. In highly strained specimens, residual martensite remains after release.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1007/s40830-019-00217-6
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“Electronic and chemical properties of nickel oxide thin films and the intrinsic defects compensation mechanism”. Poulain R, Lumbeeck G, Hunka J, Proost J, Savolainen H, Idrissi H, Schryvers D, Gauquelin N, Klein A, ACS applied electronic materials 4, 2718 (2022). http://doi.org/10.1021/ACSAELM.2C00230
Abstract: Although largely studied, contradictory results on nickel oxide (NiO) properties can be found in the literature. We herein propose a comprehensive study that aims at leveling contradictions related to NiO materials with a focus on its conductivity, surface properties, and the intrinsic charge defects compensation mechanism with regards to the conditions preparation. The experiments were performed by in situ photo-electron spectroscopy, electron energy loss spectroscopy, and optical as well as electrical measurements on polycrystalline NiO thin films prepared under various preparation conditions by reactive sputtering. The results show that surface and bulk properties were strongly related to the deposition temperature with in particular the observation of Fermi level pinning, high work function, and unstable oxygen-rich grain boundaries for the thin films produced at room temperature but not at high temperature (>200 degrees C). Finally, this study provides substantial information about surface and bulk NiO properties enabling to unveil the origin of the high electrical conductivity of room temperature NiO thin films and also for supporting a general electronic charge compensation mechanism of intrinsic defects according to the deposition temperature.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
DOI: 10.1021/ACSAELM.2C00230
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“Fabrication and characterization of functionally graded Ni-Ti multilayer thin films”. Tian H, Schryvers D, Mohanchandra KP, Carman GP, van Humbeeck J, Functional materials letters 2, 61 (2009). http://doi.org/10.1142/S1793604709000570
Abstract: A functionally graded multilayer NiTi thin film was deposited on a SiO2/Si substrate by d.c. sputtering using a ramped heated NiTi alloy target. The stand-alone films were crystallized at 500°C in vacuum better than 10-7 Torr. Transmission electron microscopy micrographs taken along the film cross section show two distinct regions, thin and thick, with weak R and B2 phases, respectively. The film compositions along the thickness were measured and quantified using the standard-less EELSMODEL method. The film deposited during the initial thermal ramp (thin regions) displays an average of 54 at.% Ni while the film deposited at a more elevated target temperature (thick regions) shows about 51 at.% Ni.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.234
Times cited: 9
DOI: 10.1142/S1793604709000570
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“Martensitic and bainitic transformations in Ni-Al alloys”. Schryvers D, Journal de physique: 4 C2, 225 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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