The Effect of Sr²⁺ on Luminescence of Ce³⁺-Doped (Ca,Sr)₂Al₂SiO₇

A series of Ce³⁺-doped (Ca,Sr)₂Al₂SiO₇ phosphors with different Ce³⁺ and Ca²⁺/Sr²⁺ concentrations were prepared by a high temperature solid-state reaction technique. To get insight into the structure-luminescence relationship, the impact of incorporation of Sr²⁺ on structure of (Ca,Sr)₂Al₂SiO₇ was first investigated via Rietveld refinement of high quality X-ray diffraction (XRD) data, and then the VUV-UV excitation and UV-vis emission spectra of (Ca,Sr)₂Al₂SiO₇:Ce³⁺ were collected at low temperature. The results reveal that the crystal structure evolution of (Ca,Sr)₂Al₂SiO₇:Ce³⁺ has influences on band gaps and Ce³⁺ luminescence properties including 4f-5d_i (i = 1-5) transition energies, radiative lifetime, emission intensity, quantum efficiency, and thermal stability. Moreover, the influence of Sr²⁺ content on the energy of Eu³⁺-O^2- charge-transfer states (CTS) in (Ca,Sr)₂Al₂SiO₇:Eu³⁺ was studied in order to construct vacuum referred binding energy (VRBE) schemes with the aim to further understand the luminescence properties of (Ca,Sr)₂Al₂SiO₇:Ce³⁺. Finally, X-ray excited luminescence (XEL) spectra were measured to evaluate the possibility of (Ca,Sr)₂Al₂SiO₇:Ce³⁺ as a scintillation material.