Computer simulation of Na2ThF6 single crystals: prediction of a phase transition under hydrostatic pressures

摘要

In this work we have performed atomistic simulations for the Na2ThF6 compound in order to investigate the predicted ferroelastoelectric and ferrobielastic P (6) over bar 2m -> P321 structural phase transition induced by hydrostatic pressure. The set of potentials obtained describe very well the structural parameters and dielectric constants at room temperature and pressure. On increasing pressure this phase transition occurs at around 6 GPa and has been observed from anomalous changes in several calculated observables. The elastic constant and piezoelectric coefficient tensors satisfy the symmetry criteria imposed by the P (6) over bar 2m -> P321 ferroic phase transition.