Compositional Dependence of Photoluminescence of ZnGa₂O₄

The photoluminescence characteristics of the zinc gallate have been investigated as a function of the composition and the firing atmosphere. Two distinct emission bands were observed whose peaks are 360 nm and 430 nm respectively. These emission bands are considered to be from two different emission centers. For ZnO/Ga₂O₃=49.3/50.7 or higher, 430 nm band is predominant and for ZnO/Ga₂O₃=49.2/50.8 or lower, 360 nm band becomes predominant, whereas 430 nm band is almost completely suppressed. The shift of emission peak is thought to be due to the change of the cation distribution with the zinc content in the spinel zinc gallate. Also, the emission centers responsible for the 360 nm band are considered to be more efficient energy absorbers than the ones for the 430 nm band. Highly efficient green emitting phosphor was obtained by activating Zn-deficient zinc gallate with manganese.