Abstract
Fine‐particle 
red phosphor (∼1 μm) with spherical shapes was synthesized from a submicron‐size yttrium (europium) oxide, obtained by controlled hydrolysis of yttrium alkoxide‐europium chloride, employing sodium thiosulfate as a sulfurizing agent. Various preparative parameters, such as activator concentration, firing temperature, and duration, were optimized for the maximum luminance at low‐voltage excitation (<1000 V), and the best phosphor was compared with a commercial phosphor. The best phosphor with an improved luminance can be obtained for the phosphor prepared at 1000°C for 6 h and doped with 4 mol % europium. The fine‐grained phosphor showed increased luminance at low current densities 
and decreased luminance at high current densities. The improvement in luminance is attributed to the small particle size of the phosphors and uniform distribution of the activator. Synthesized phosphors were analyzed using X‐ray diffraction and scanning electron microscopy to interpret the observed luminescent properties. © 2000 The Electrochemical Society. All rights reserved.