Detection of foreign phases in doped a-alumina powders by thermoluminescence

The thermoluminescence (TL) after excitation by UV or X-rays radiation of doped α-alumina powders is investigated. In the case of zirconia, the alumina-zirconia composites present five of the characteristic peaks of zirconia at –170, –145, –90, 0 and 95°C. After a thermal treatment of mixed oxides, a new peak is observed at –35°C in TL. This peak reveals the presence of stabilized tetragonal zirconia in the material. In the case of calcium, the TL curves of α-alumina doped by calcium present a double peak around 110 and 130°C which can be attributed to the presence of the hibonite phase: CaAl12O19. Moreover, in the case of zirconia, by comparing this analysis with those realised by X-rays diffraction (XRD), it can be shown that the TL has one better limit of detection than the XRD.