Phase transformation B1 to B2 in TiC, TiN, ZrC and ZrN under pressure
| Autor: | Ivashchenko, V. I., Turchi, P. E. A., Shevchenko, V. I. |
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| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Condens. Matter Phys., 2013, vol. 16, No. 3, 33602 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.5488/CMP.16.33602 |
| Popis: | 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. Comment: 9 pages, 4 figures |
| Databáze: | arXiv |
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