Site Occupancy Studies and Luminescence Properties of Emission Tunable Phosphors Ca9La(PO4)7:Re (Re = Ce3+, Eu2+)

The structure, site occupancies, and photoluminescence (PL) properties of Ce3+- or Eu2+-doped Ca9La(PO4)7 phosphors were investigated in this work. The powder X-ray diffraction (XRD) data and Rietveld refinement results showed that the phosphors are pure phases. The vacuum ultraviolet-ultraviolet–visible (VUV-UV–vis) spectra and decay curves confirmed that the Ce3+ and Eu2+ ions in Ca9La(PO4)7 occupied two crystal sites. Additionally, the tunable color can be obtained by adjusting doping concentration and altering temperature. The fabricated w-LED lamp based on Eu2+-doped Ca9La(PO4)7 phosphor gave properties with a color rendering index (CRI) of 85.26, CIE chromaticity coordinates of (0.358, 0.307), and color temperature (CCT) of 4329 K.