Distribution and solubility limit of AI in Al₂O ₃-doped ZnO sintered body

A few mol% Al₂O₃-doped ZnO sintered body forms a substitutional solid solution and the semi-conducting property is drastically affected by the content of the dissolved AI. It was suggested from the results of XRD and EPMA that Al existed in the ZnO sintered body in the form of ZnAl₂O₄. Furthermore, the distribution of ZnAl ₂O₄ was visualized by AFM and SEM. It was, however, difficult for these techniques to detect dissolved Al in ZnO grains directly. The SIMS mapping suggested that the trace amount of Al (approximately 0.3 atomic%) dissolved into ZnO grains because of high sensitivity for trace impurities. This result was consistent with the change in lattice constants of ZnO with Al dissolution.