THERMOLUMINESCENCE OF ZRO2

The thermoluminescence of ZrO2 samples, both pure and doped with titanium, irradiated with low doses of x rays has been studied. The glow curve of ZrO2(Ti) exhibits, in the temperature range 100° to 350°K, four main peaks all having the same spectral composition. The pure ZrO 2 presents a similar glow curve but having a. luminous intensity about 2×103 times lower than that of the doped material. These data indicate that Ti4+ ions act as thermoluminescent centers. Activation energies were calculated by means of the initial rise method and also by using the shape of the isolated peaks. The electron traps probably are related to oxygen vacancies. In fact, the luminous intensity increases when the vacancy concentration increases, and the activation energies calculated from the dielectric constant are close to the activation energies obtained from glow peak data. The build-up curves indicate that the vacancies, acting as trapping centers, exist prior to the irradiation and are probably of the same type for all of the thermoluminescent peaks.