Luminescence spectroscopy of Ce3+-doped ABaPO4 (A=Li, Na, K) phosphors

Ce3+ doped ABaPO(4) (A=Li, Na, K) phosphors were prepared by conventional high temperature solid-state reaction. The phosphors were investigated by XRD, photoluminescence excitation and emission spectra, and luminescence decay curves. The five 5d levels corresponding to the 4f(1)-> 4f(0)5d(1) transition of Ce3+ ions were identified. The spectroscopic parameters, e.g., the 5d barycenter, the crystal-field splitting, and the Stokes shift, were discussed. LiBaPO4:Ce3+ phosphor could be efficiently excited by the near-UV lights (330-420 nm) and showed a broad emission band in the range of 430-620 nm with the maximum wavelength at 468 nm. In contrast, Ce3+-doped NaBaPO4 and KBaPO4 showed only excitation bands in a limited UV region (230-370 nm) and have blue emission at 385 nm and 416 nm, respectively. The temperature quenching of luminescence and the chromaticity coordinates were reported. The luminescence properties were discussed by analyzing the crystal structure and the local surroundings of Ce3+ ions on the Ba2+ sites.