SYNTHESIS OF RED-EMITTING, SMALL-PARTICLE SIZE LUMINESCENT OXIDES USING AN OPTIMIZED COMBUSTION PROCESS

A novel ceramic synthesis technique, combustion synthesis, was explore d to produce red-emitting Cr3+-doped Y3Al5O12 and Eu3+-doped Y2O3 phos phors with improved physical and luminescent properties, This techniqu e involves the reaction of metal nitrates (oxidizers) and an organic f uel (urea, carbohydrazide, glycine) at 500 degrees C. Resulting powder s are well-crystallized, with a large surface area and small particle size, The spectral energy distribution was observed using photolumines cence measurements, The effects of processing parameters such as type of fuel, fuel-to-oxidizer ratio, furnace temperature, and batch water content were studied, An increase in phosphor brightness with increasi ng reaction temperature was observed, Postreaction heat treatments (10 00 degrees, 1300 degrees, and 1600 degrees C) increased the luminous i ntensity of as-synthesized powders, Residual carbon content and chromi um site symmetry were investigated as possible explanations for the in crease in brightness with increasing heat treatment temperature, By ta iloring the reaction chemistry, the optimal conditions for producing t he most luminescent phosphors have been identified.