High pressure behavior and structural properties of transition metal carbides

Abstract

A pressure induced structural phase transition from NaCl-type (B₁) to CsCl-type (B₂) structure has been predicted in transition metal carbides, namely TiC, ZrC, NbC, HfC, and TaC by using an interionic potential theory with modified ionic charge (Z_m ), which includes Coulomb screening effect due to d-electron. The phase transition pressure (P_T ) relies on large volume discontinuity in pressure–volume relationship, and identifies the structural phase transition from B₁ phase to B₂ phase. The variation of second-order elastic constants with pressure follows a systematic trend identical to that observed in other compounds of NaCl-type structure. The Born criterion for stability is found to be valid in transition metal carbides.

Keywords:

• high pressure
• phase transition
• equation of state
• elastic properties
• transition metal carbides

Acknowledgements

The authors are grateful to the Madhya Pradesh Council of Science and Technology (MPCST). S.P. Sanyal thanks CSIR, New Delhi, for the partial financial support.