Analysis of structural properties of refractory compounds at high temperature and pressure using a potential model

• We have investigated the high-pressure structural transition of TMNs.
• A modified model (RTBIP) (including the temperature effect) has been developed.
• Phase transition pressures are associated with a sudden collapse in volume.
• Our model is able to explain Cauchy violations.
• We have extended our study to elastic and mechanical properties of these compounds.

In this paper we focused on the structural and elastic properties of four transition metal mononitrides (TMNs) (M=Ti, Nb, Hf and Zr) by using realistic three body interaction potential (RTBIP) model, including the role of temperature. These TMN compounds have been found to undergo NaCl (B1) to CsCl (B2) phase transition, at a pressure quite high as compared to other binary systems. We successfully obtained the phase transition pressures and volume changes at different temperatures. In addition, elastic constants of TMNs at different temperatures are discussed. The present theoretical results have been compared with the available experimental data and predictions of LDA theory.