Structural phase transformations in InP under pressure: A molecular-dynamics study

The pressure induced structural phase transformations of InP up to 100 GPa are investigated using molecular-dynamics simulations. The calculated InP equation of state for the zincblende (ZB) phase at room temperature is in excellent agreement with experiments as well as several thermodynamic properties validating the interatomic potential employed in the simulations. Results show a sequence of dynamic structural transformations from ZB → rocksalt (RS) at 10 GPa, from RS → rhombohedral (RH) at 14 GPa, and from RH → CsCI at 70 GPa. The RS → RH transformation is a weakly first order transition while the other two transformations are typical first order transitions which present large volume drop and hysteresis in the reverse transformation. The RH intermediate phase between RS and CsCI was never considered for InP even though it was predicted for other materials. The ZB → RS transition uses a Pmm2 pathway while the RS → RH → CsCI is consistent with the Buerger mechanism which uses the R3m pathway.