Cr-related luminescence in α-alumina prepared by sintering and oxidizing

Different types of α-alumina were prepared by sintering alumina powder with Cr dopant and by oxidizing PtAl coating, respectively. The Cr-related luminescence in α-alumina has been examined using laser excitation. The results indicate that the intensity of luminescence related to the actual Cr content presented in the probed zone for sintered alumina powder with different Cr concentration. However, for the alumina developed on PtAl coating, the Cr dopant concentration in the alumina scale showed little change during the earlier time of oxidation and the growing of alumina scale account for the increase of luminescence intensity. However, the Cr concentration decreased with extending oxidation time and the luminescence intensity changed little during that period due to the relatively stable Cr content in alumina scale.