EFFECTS OF ALUMINUM DOPING UPON COLOR FORMATION IN ZINC-OXIDE POWDERS

The effects on the reflectance spectra of zinc oxide powders, of heat treatment, and of mechanical grinding were investigated for both undop ed and aluminum-doped ZnO. A broad absorptance band at 390-400 nm was induced in the undoped powders both by heating in air and by grinding. From a comparison with electron paramagnetic resonance data from the literature, the band could be related to oxygen vacancies. It was foun d that aluminum doping suppresses the band formation induced by grindi ng; however, the doping does not suppress the band formation induced b y heat treatment.