High-Luminance Y[sub 2]O[sub 3]:Eu[sup 3+] Phosphor Synthesis by High Temperature and Alkali Metal Ion-Added Spray Pyrolysis

We obtained a high-luminance red phosphor by spray pyrolysis without postheating treatment using a high-temperature furnace with a long residence time and the addition of alkali metal salts to the precursor solution. The luminance under UV and vacuum UV radiation was about 100 and 90% that of the conventional phosphor made by solid-state reaction. The phosphor with the highest luminance was synthesized from a precursor solution that contained a lithium salt at 1.6 times the total of the yttrium and europium molar quantity. Optimum pyrolysis conditions were 1600°C temperature and 12 s residence time. The median particle diameter of the phosphor was 1.0 μm, which is much smaller and less agglomerated than the commercial phosphor made by solid-state reaction, whose median diameter was 3.5 μm. Compared with the phosphor having 1.5 μm median particle diameter by the solid-state reaction, the luminance of the phosphor in this study was 125%. An X-ray diffraction study indicated that the highest luminance phosphor obtained by the addition of a lithium salt had little strain in the crystal and that crystal growth was promoted by the additive.