Study on the intrinsic defect in Er2O3 crystal from combined first-principles and thermodynamic calculation

Erbium oxide (Er2O3) crystal is expected to be a new generation of persistent luminescence devices. The intrinsic point defects have a great influence on the properties of crystals. So, we investigated the formation energy of intrinsic point defect in Er2O3 crystal by density functional theory (DFT) and thermodynamic calculation. The effect of vibration entropy variation with temperature is considered. The results show that the influence of vibrational entropy on the formation energy should not be ignored under high-temperature. The defect formation energy under varied temperatures and oxygen partial pressure has been obtained. The results indicate that the most stable defect change from oxygen vacancies to erbium vacancies when the Fermi level increases from valence band maximum (VBM) to conduction band minimum (CBM). Erbium vacancies are predicted as shallow level acceptors. Fermi pinning effect causes the crystal to have a p-type conductive behavior. Our calculated result can provide the optimization condition for adjusting the main defect types to satisfy the needs of application.