Regensburg 2022 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 8: Crystallography in Materials Science, Microstructure and Dielectric Properties
KFM 8.2: Talk
Monday, September 5, 2022, 15:20–15:40, H7
Impact of the stacking sequence on the stability of transition-metal diborides — •Thomas Leiner1, Nikola Koutná2, Paul H. Mayrhofer2, and David Holec1 — 1Department of Materials Science, Montanuniversität Leoben, Austria — 2Institute of Materials Science and Technology, TU Wien, Austria
Transition-metal diborides are a very hard and brittle type of materials, which, among others, find their use as protective coatings, because of their excellent heat conductivity, oxidation stability and wear resistance.
The investigated diborides XB2 X=(Cr, Hf, Mn, Mo, Nb, Re, Ta, Ti, V, Zr) occur in three different known stackings, the A-A-A-A stacking of e.g. TiB2, the A-B-A-B stacking of ReB2 and the A-B-B-A stacking of WB2.
In this work, the impact of the stacking sequence on the stability of diborides is investigated via ab initio methods (VASP) and phonon analysis. The energy levels and the energy barriers for the different structures of the transition-metal diborides is calculated and evaluated. The stability of observed local and global energy minima are further investigated by assessing their phonon density of states and their phonon frequencies.
Predictions about a possible stability of certain stackings are made and the behaviour of different diborides was compared to each other.