Suppression of YAG phase formation in YAP:Ce pellets

It is difficult to obtain the pure YAP phase in YAP:Ce pellets synthesized by solid-state reaction at high temperature (up to 1500°C), because a small amount of YAG (Y₃Al₅O₁₂):Ce tends to form, resulting in additional emission and degrading the scintillation performance. We attempted three methods to suppress the formation of this YAG phase: a) codoping with Ca, B and Ba, b) adding Ba and F compounds as flux, and c) adding excess Y. The presence or absence of a YAG phase in the YAP pellets was determined by photoluminescence (PL), radioluminescence (RL) and reflectivity spectra. The most significant suppression of the YAG phase was achieved by adding 10% excess Y, after which the YAG emission peak was nearly completely suppressed in the RL and PL spectra, and no YAG phase absorbance was found in reflectivity spectra compared to stoichiometric YAP pellets.