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arXiv · 1309.6210

Phase transformation B1 to B2 in TiC, TiN, ZrC and ZrN under pressure

V. I. Ivashchenko·P. E. A. Turchi·V. I. Shevchenko
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Abstract

Phase stability of various phases of MX (M = Ti, Zr; X = C, N) at equilibrium and under pressure is examined based on first-principles calculations of the electronic and phonon structures. The results reveal that all B1 (NaCl-type) MX structures undergo a phase transition to the B2-structures under high pressure in agreement with the previous total-energy calculations. The B1-MX structures are dynamically stable under very high pressure (210-570 GPa). The pressure-induced B2 (CsCl-type) MC phases are dynamically unstable even at high pressures, and TiN and ZrN are found to crystallize with the B2-structure only at pressures above 55 GPa. The first-order B1-to-B2 phase transition in these nitrides is not related to the softening of phonon modes, and the dynamical instability of B2-MX is associated with a high density of states at the Fermi level.

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V. I. Ivashchenko, P. E. A. Turchi, V. I. Shevchenko. 2013-09-24. Phase transformation B1 to B2 in TiC, TiN, ZrC and ZrN under pressure. https://doi.org/10.5488/cmp.16.33602

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