Photoluminescence of ZnGa2O4 phosphor prepared by a microencapsulation method

An inorganic luminescent material has been prepared using the microencapsul ation method. A chemical precipitation process was used to produce a unifor m ZnO layer on the surface of Ga2O3 particles. The best encapsulating effec t for Ca2O3 with particle size under 5 mu m, is obtained with the use of ur ea concentration of 0.7 M in an 0.1 M Zn(NO3)(2).6H(2)O aqueous solution, h eated at 75 degrees C for 5-15 h. This composite powder requires a firing t emperature of 1100 degrees C and soaking time of 5 h, to synthesize phospho rs with good repeatability. The synthetic ZnGa2O4 phosphor emits close to b lue light at 455 nm under 254 nm excitation, and the best emission intensit y is obtained when the molar ratio of ZnO/Ga2O3 approximately equals 1.0. T he produced powder is anterior to the powder obtained by the traditional me chanical mixing which requires firing temperature above 1100 degrees C with longer soaking time and emits a broad-band spectrum with a peak at 470 nm. (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.