Microemulsion‐Mediated Synthesis and Characterization of YBO 3 : Ce 3+ Phosphors

Monophasic YBO 3 : Ce 3+ phosphors were successfully synthesized via microemulsion route with various volumetric ratios of water to oil ( W s ). The phosphors had uniform size distribution on the nanometer scale with spherical morphology owing to confinement of the constituent cations by the aqueous micelles. As W s was decreased from 0.1 to 0.025, the average size of the produced particles decreased from 189 to 90 nm due to reduced sizes of aqueous micelles. Upon 363 nm excitation, the phosphors exhibited strong and broad blue emission ranging from 375 to 520 nm, which arise from the 5 d to 2 F 5/2 and 2 F 7/2 transitions of Ce 3+ ions. The emission intensity declined with the decrease of particle size, and this result can be ascribed to the increment of surface defects in small particles. YBO 3 : Ce 3+ phosphors, that were prepared with W s  = 0.1 at high calcination temperatures, exhibited high luminescent intensity due to less defects. The mechanisms of enhanced crystallinity and luminescence as a function of W s and calcinations temperature were investigated in detail.