Pressure and temperature phase diagram of Gd2Ti2O7 under irradiation

Abstract

The pressure and temperature phase diagram of Gd2Ti2O7 under irradiation are calculated by means of molecular dynamics calculations. The critical temperature for amorphization obeys a linear law with pressure. Gd2Ti2O7 under irradiation transits towards the fluorite above this temperature and amorphizes below. The configuration of the Ti interstitial reveals to be the key of the amorphizability of Gd2Ti2O7. Its stability depends upon disorder and pressure. Low pressure promotes the stabilization of Ti linked-polyhedra that drive the system to the amorphous state under irradiation. Conversely, high pressure activates its destabilization to interstitials that recombine with vacancies, driving the system to the fluorite structure under irradiation.