Nano-crystals precipitation and upconversion luminescence properties in Er3+/Yb3+ co-doped fluoride phosphate glass-ceramics

Er3+/Yb3+ co-doped transparent glass-ceramics containing Ca5(PO4)3F nano-crystals were prepared and their upconversion properties were investigated. Transparent glass-ceramics were obtained after heat treatment at the first crystallization temperature, TEM images showed that Ca5(PO4)3F nano-crystals of 10–20 nm in diameter precipitated uniformly in the glass matrix, which is similar to the result of those calculated by Scherrer equation. Comparing with the samples before heat treatment, high efficiency upconversion luminescence of Er3+ at 547 nm and 667 nm was observed in the glass-ceramics under 980 nm excitation, and the intensity of red emission showed different tendency to that of green emission after nano-crystals precipitation. The reasons for the highly efficient upconversion luminescence in glass-ceramics were discussed.