Improvement of photoluminescence properties of Ce3+- doped CaSrAl2SiO7 phosphors by charge compensation with Li+ and Na+

In this work, we prepared CaSr1-xAl2SiO7:xCe3+ (0.03 ≤ x ≤ 0.12) and CaSr0.94Al2SiO7:0.03Ce3+,0.03 M+ (M+ = Li+ and Na+) phosphors via solid-state reaction method. Structural and photoluminescence (PL) properties of the phosphors were also investigated. The prepared phosphors formed an orthorhombic crystal structure with the P212121 space group. CaSr1-xAl2SiO7:xCe3+ phosphors were effectively excited by near-ultraviolet (UV) light (345 nm), which is suitable with the emission of near-UV light emitting diode chips. A broad blue emission (402 nm) was detected in CaSr1-xAl2SiO7:xCe3+ and CaSr0.94Al2SiO7:0.03Ce3+,0.03 M+ phosphors; this was attributed to the 4f05d1 → 4f1 transition of Ce3+. To maintain charge equilibrium, charge compensators, such as monovalent Li+ and Na+ ions, were doped into the CaSr0.97Al2SiO7:0.03Ce3+ phosphor, significantly improving its PL properties. The strongest emission intensity was achieved in CaSr0.94Al2SiO7:0.03Ce3+,0.03Li+ phosphor. Addition of Li+ charge compensator was highly effective in improving PL properties of CaSr0.97Al2SiO7:0.03Ce3+ phosphors.