PHOTOLUMINESCENT CHARACTERIZATION OF ZIRCONIA-TOUGHENED ALUMINA (ZTA) CERAMICS

Photoluminescence (PL) investigations in zirconia-toughened alumina (ZTA) with three different zirconia contents were carried out. The PL emission spectra consist of a dominant structureless band centered at about 500 nm which exhibits a main excitation band centered near 292 nm with a subsidiary peak at about 254 nm. The 500 nm luminescence intensity is considerably increased by grinding. Luminescent intensities were plotted against zirconia content of ZTA samples. A good linear fit is found between the intensity ratio I-254/I-292 and the total or tetragonal phase amount (wt%) of ziconia. After severe grinding, the ratio I-254/I-292 tends to be independent of zirconia content. The results are analyzed on the basis of defect centres which would be favored by the tetragonal to monoclinic transformation.