LAUSR

Abstract Eu2+-doped KSrPO4 and KBaPO4 phosphors have attracted much attention for white light-emitting diode (W-LED) applications. In this study, pulsed laser ablation in liquid (PLAL) was carried out in order to micronize fatally aggregated particles of KSrPO4:Eu2+ and KBaPO4:Eu2+ by H2 reduction under a high temperature to a suitable size for the W-LED applications. The diameter of aggregated particles after H2 reduction (approximately 2.0 μm) was successfully decreased to about half by PLAL, which is suitable for the W-LED applications. Furthermore, PLAL was found to maintain the luminescence intensity as high as before PLAL, indicating no contamination of impurities from processing devices. In addition, PLAL was also applied to KSrPO4:Eu3+ and KBaPO4:Eu3+ before H2 reduction and found not only to maintain the luminescence intensity but also to reduce the valence of Eu ions (Eu3+ → Eu2+). These results show not only the effectiveness of the micronization but also the feasibility of laser induced photo reduction of Eu ions in phosphate crystals for the W-LED applications by PLAL.