Vacancy formation enthalpy at high pressures in tantalum

Abstract

Using a mixed basis pseudopotential method, total energy calculationswere performed to obtain the enthalpy of vacancy formation in Ta as afunction of pressure, which is important for understanding the effectsof pressure on mechanical properties. The vacancy formation enthalpyis found to increase from 2.95 eV at ambient pressures to 12.86 eV at300 GPa, and the vacancy formation volume decreases from being 53 ± 5%of the bulk volume per atom at ambient pressure to 20 ± 2% at300 GPa, for a 54-atom supercell. We also show that there is a strongcorrespondence between the vacancy formation enthalpy and the meltingtemperature in Ta.