Abstract
Eu-doped GaN crystals were synthesized at 600-750°C and N2 pressure of 5 MPa from 1 mol% Eu-added Na-Ga melts. The yield and morphology of crystals varied with temperature and Na mole fraction, rNa=Na/(Na+Ga) in the melts. Colorless transparent columnar crystals of Eu-doped GaN were obtained as crusts formed on the Na-Ga melt surface at rNa=0.67 and 650 or 700°C. Under an ultraviolet light, the crusts glowed red. A strong emission peak concerned with the intra-4f transition of Eu3+ from 5D0 to 7F2 was observed at 621 nm in the photoluminescence (PL) spectrum. The maximum PL intensity was observed in the sample prepared at rNa=0.67 and 650°C.
