From blue to cyan emission: Ce3+ and Tb3+ co-doped silicon phosphate phosphors with high thermal stability

Abstract

A series of Ca₁₅(PO₄)₂(SiO₄)₆:xCe³⁺,yTb³⁺ phosphors have been prepared by a high-temperature solid-state reaction. Under the excitation of near-UV with 371 nm wavelength, Ca₁₅(PO₄)₂(SiO₄)₆:xCe³⁺ phosphors exhibit strong blue emission with a broad peak at 432 nm. Based on the photoluminescence of Ca₁₅(PO₄)₂(SiO₄)₆:xCe³⁺ phosphors, the coordination environment around Ce³⁺ ions and the concentration quenching mechanism are inferred. With the doping of Tb³⁺ ions into Ca₁₅(PO₄)₂(SiO₄)₆:1.33%Ce³⁺, the luminescence color from blue to cyan can be well tuned. By measuring the luminescence intensity and lifetime of the as-prepared phosphors, it can be judged that there exists an energy transfer from Ce³⁺ to Tb³⁺. To achieve white light, the optimal Ca₁₅(PO₄)₂(SiO₄)₆:1.33%Ce³⁺, 9%Tb³⁺ phosphors are mixed with commercial SrAlSiN₃:Eu²⁺ powders and finally warm white light emission could be obtained. The results show that Ca₁₅(PO₄)₂(SiO₄)₆:xCe³⁺,yTb³⁺ phosphors have potential applications in warm white light-emitting diodes.