Upconversion and Near Infrared Emission of Rare Earth Ions in Chalcohalide Glass at the Early Stage of Crystallization

Nd3+, Er3+ ions doped 0.9(Ge0.25Ga0.10S0.65)-0.1CsBr chalcohalide glass were prepared via melt-quenching method, and heat treated at 360 degrees C in high purity Ar gas atmosphere for different hours for the early stage of crystallization. The effect of heat treatment durations on visible upconversion luminescence and near infrared emission from Nd3+ ions and Er3+ ions were investigated. The specimens kept amorphous status until the heat treatment duration extended to 10 hours, for Ga2S3 nano-crystal formation in glass matrix. The stark splitting in visible upconversion luminescence center at 600 nm from Nd3+ ions weakened, and disappeared, and the shape of infrared emission centered at 1 550 nm from Er3+ ions changed, with the heat treatment duration increased. The lifetime of Nd3+: F-4(3/2) level and Er-+(3): I-4(13/2) level dropped, then increased with heat treatment duration increased. X-ray diffraction patterns and transmission electron microscope images confirmed the amorphous state and Ga2S3 nano-crystals formation in glass matrix. The rare earth ions local environment changes with heat treatment duration were proposed, based on the emission and lifetime changes. This research will be helpful for the understanding of rare earth doped chalcohalide crystallization mechanism and processes.