Investigation on the luminescence of RE3+ (RE = Ce, Tb, Eu and Tm) in KMGd(PO4)2 (M = Ca, Sr) phosphates

The VUV excited luminescent properties of Ce3+, Tb3+, Eu3+ and Tm3+ in the matrices of KMGd(PO4)2 (M = Ca, Sr) were investigated. The bands at about 165 nm and 155 nm in the VUV excitation spectra are attributed to host lattice absorptions of the two matrices. For Ce3+-doped samples, the Ce3+ 5d levels can be identified. As for Tb3+-doped samples, typical 4f–5d absorption bands in the region of 175–250 nm were observed. For Eu3+ and Tm3+-doped samples, the O2−–Eu3+ and O2–Tm3+ CTBs are observed to be at about 229 nm and 177 nm, respectively. From the standpoints of color purity and luminescent efficiency, KCaGd(PO4)2:Tb3+ is an attractive candidate of green light PDP phosphor.