Thermo-stimulated luminescence of ion-irradiated yttria-stabilized zirconia

Yttria-stabilized zirconia (ZrO2:Y3+) single crystals (with 9.5 mol% Y2O3) were irradiated with ions (from 1 MeV He to 2.6 GeV U). Electron paramagnetic resonance (EPR) data show that two kinds of colour centres (F+-type and T centres) are produced. Thermo-stimulated luminescence (TSL) data exhibit a quite strong peak at similar to 500-550 K in the glow curves of all irradiated samples regardless of the ion species and energy. Moreover, the 3D-TSL measurements reveal that this peak is correlated with a light emission at a wavelength of similar to 620 nm (i.e. photon energy similar to 2 eV). The TSL peak maximum temperatures are consistent with characteristic temperatures of about 500 K of annealing stages of colour centres. However, the trap-depth energies (ranging between 0.7 and 1.4 eV) deduced from the initial rise of partially cleaned TSL peaks, or from a rough approximation using Urbach's formula, are rather larger than the activation energies for defect recovery, ranging between 0.3 and 0.7 eV, as deduced from the EPR data. The processes involved in TSL are discussed in relation to available photoluminescence and defect energy-level data.