Transition of Gd2O3:Eu Phosphor to GdBO3:Eu Phosphor with Boron Concentration in the Spray Pyrolysis

The transition of europium-doped gadolinium oxide phosphor to gadolinium borate phosphor with the concentration of boron in the spray pyrolysis was investigated. The particles prepared from spray solution below 10 wt% boric acid of prepared phosphor had crystal structure of Gd2O3:Eu phosphor, in which the crystallinity of the particles decreased with increasing the boron concentration. A single phase GdBO3:Eu phosphor particles were prepared from spray solution above 50 wt% boric acid of prepared phosphor. The phosphor particles prepared from spray solution with 20 wt% boric acid of prepared phosphor had no XRD peaks of Gd2O3:Eu and GdBO3:Eu. Therefore the phosphor particles prepared from spray solution with 20 wt% boric acid of prepared phosphor had the lowest photoluminescence intensity under ultraviolet and vacuum ultraviolet. GdBO3:Eu and Gd2O3:Eu phosphor particles prepared from spray solutions with proper concentrations of boric acid had good photoluminescence intensity under vacuum ultraviolet. The morphology of the phosphor particles were strongly affected by the concentrations of boric acid added into spray solution.