Structural phase stability and elastic properties of refractory carbides

In the present paper, we have investigated the high-pressure structural phase transition of refractory carbides (ZrC, HfC, NbC and TaC). A Modified Interaction Potential Model with Covalency (MIPMCv) has been applied. Phase transition pressures are associated with a sudden collapse in volume showing the occurrence of first order phase transition. At compressed volumes, these compounds are found in CsCl phase. The phase transition pressures and associated volume collapses obtained from present potential model show a generally better agreement with available experimental data than others. The elastic constants and bulk modulus are also reported. Our results are in general in good agreement with experimental and theoretical data where they are available, and provide predictions where they are unavailable.

We have computed the relative volume changes V(P)/V(0) corresponding to the values of r and r′ at different pressures and plotted them against the pressure in Fig. 2 (a–d) for ZrC, HfC, NbC and TaC.Figure optionsDownload as PowerPoint slideHighlights
► We have investigated the high-pressure structural phase transition of refractory carbides (ZrC, HfC, NbC and TaC).
► Phase transition pressures are associated with a sudden collapse in volume.
► Our model has conquered successfully the previous drawbacks which have been ignored by the previous authors.
► Our results of bulk modulus match with experimental results and better than others.