Spectroscope properties of KCaY(PO4)2:Eu3+ in vacuum ultraviolet region

In order to investigate the energy migration mechanisms of Eu3+ doped hexagonal KCaY(PO4)2 in vacuum ultraviolet (VUV) region, KCaY1−x(PO4)2:Eux3+ (0 ≪ x < 0.1) are prepared and their photoluminescence (PL) properties are evaluated under 147 nm excitation. Monitored by 616 nm emission, the weak band around 136–162 nm in the excitation spectra of KCaY0.95(PO4)20.05:Eu3+ could be assigned to the absorption of PO43−. The sharp peak at 213 nm which overlaps with the charge transition band (CTB) of Eu3+–O2− at about 177–280 nm should be assigned to the transition to 3H4 levels of Eu3+. Under 147 nm excitation the strongest emission peak is located at about 616 nm. When x reaches 0.05 in KCaY1−x(PO4)2:Eux3+(0 < x < 0.1), the optimum emission intensity is obtained. A main reason for the low quenching concentration of Eu3+ is that Eu3+ occupies not only the Y3+ position but also the K+ and Ca2+ sites, so the energy migration among Eu3+ ions could be in three-dimensional.