David Holec

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We present a scale-bridging approach for modeling the integral elastic response of polycrystalline composite that is based on a multi-disciplinary combination of (i) parameter-free first-principles calculations of thermodynamic phase stability and single-crystal elastic stiffness; and (ii) homogenization schemes developed for polycrystalline aggregates and(More)
Table 1: Lattice vectors and fractional coordinates of atoms for the primitive cells used for construction of {100}, {110}, {111}, and {112} surfaces of the B1 structure. The N-terminated {111} slab is obtained by exchanging Al and N lattice sites. {100} {110} {111} {112} a1 1/2 −1/2 0 √ 2/2 0 0 √ 2/4 − √ 6/4 0 √ 3 0 0 a2 1/2 1/2 0 0 1 0 √ 2/4 √ 6/4 0 0 √(More)
For non-centrosymmetric crystals, the refinement of charge-density maps requires highly accurate measurements of structure-factor phase, which can now be obtained using the extinction-free convergent-beam electron microdiffraction method. We report here accurate low-order structure-factor phases and amplitudes for gallium nitride (GaN) in the wurtzite(More)
The complex structure of Ta2O5 led to the development of various structural models. Among them, superstructures represent the most stable configurations. However, their formation requires kinetic activity and long-range ordering processes, which are hardly present during physical vapor deposition. Based on nano-beam X-ray diffraction and concomitant ab(More)
D. Holec, Ferenc Tasnadi, P. Wagner, M. Friak, J. Neugebauer, P. H. Mayrhofer and J. Keckes, Macroscopic elastic properties of textured ZrN-AlN polycrystalline aggregates: From ab initio calculations to grainscale interactions, 2014, Physical Review B. Condensed Matter and Materials Physics, (90), 18, 184106. http://dx.doi.org/10.1103/PhysRevB.90.184106(More)
The development of interfacial coherency stresses in TiN/AlN bilayer and multilayer films was investigated by finite element method (ABAQUS) using the four-node bilinear quadrilateral axisymmetric element CAX4R. The TiN and AlN layers are always in compression and tension at the interface, respectively, as may be expected from the fact TiN has larger(More)