Soft Chemistry Routes to YPO4-Based Phosphors: Dependence of Textural and Optical Properties on Synthesis Pathways

Different liquid routes have been used to prepare Eu 3+ -activated YPO 4 phosphors. These materials have been compared with conventionally obtained YPO 4 . For the first time (to our knowledge), a specific sol−gel approach has been developed to produce this material. All phases have been checked with X-ray diffraction (XRD) and solid-state nuclear magnetic resonance. Evaluation of the textural properties of the materials with XRD and scanning electron microscopy have demonstrated that the synthesis pathway can greatly influence the morphology of the materials and that in particular, the sol−gel route yields the smallest particles with the narrowest distribution. The optical study of the obtained phosphors shows that even if all materials exhibit comparable fluorescence in term of energetic scheme, some discrepancies can be noted according to the preparation route. In particular, liquid derived materials show shorter emission lifetimes; this observation has been correlated with residual OH groups in these materials. We have also observed that the emission yield, which is a fundamental parameter for applications purposes, depends on the preparation and that the coprecipitation technique leads to the best efficiency.