Submicron-sized spherical yttrium oxide based phosphors prepared by supercritical CO2-assisted aerosolization and pyrolysis

Abstract

The synthesis of Eu(III)- and Tb(III)-doped yttrium oxide phosphor powders by supercritical ${\mathrm{CO}}_{\mathrm{2}}$ -assisted aerosolization and pyrolysis (at 1010 °C) from aqueous solutions of ${\mathrm{Y(NO}}_{\mathrm{3}}{\mathrm{)}}_{\mathrm{3}},$ ${\mathrm{Eu(NO}}_{\mathrm{3}}{\mathrm{)}}_{\mathrm{3}},$ and ${\mathrm{Tb(NO}}_{\mathrm{3}}{\mathrm{)}}_{\mathrm{3}}$ is presented. Dense, submicron aerosols are formed by contacting aqueous solutions of the precursor metal nitrates with supercritical ${\mathrm{CO}}_{\mathrm{2}}$ at 1500 psi, and decompressing the mixture through a restrictor nozzle into a heated tube. X-ray diffraction data indicate that the powders are crystalline, and consist of a single phase. Scanning electron microscope shows that they are spherical in morphology and less than 1 μm in size with average diameters of $\text{∼0.2\hspace{0.17em}μ}\mathrm{m}.$ The cathodoluminescence intensity of the ${\mathrm{Y}}_{\mathrm{1.91}}{\mathrm{Eu}}_{\mathrm{0.09}}{\mathrm{O}}_{\mathrm{3}}$ powders, annealed at 1200 °C for 1 h, is more than twice greater than that of the industrial standard (P56, 3–10 μm in diameter) phosphor. The phosphors synthesized by this method are promising candidates for use in high-resolution low-voltage flat panel displays.