Thermal quenching and luminescence decay in self-activated La2W3O12

Lanthanum tritungstates, La2W3O12, were prepared by using a conventional high-temperature solid-state reaction. The formation of a single-phase compound with the monoclinic structure of La2W3O12 was verified through X-ray diffraction (XRD) studies. The luminescence propeities of La2W3O12 were investigated by using optical and laser-excitation spectroscopy. The excitation and the emission spectra and the decay curves were measured in the temperature range 7 − 300 K. The charge-transfer transition of WO 4 2− was identified in the excitation and the emission spectra under excitation by ultraviolet radiation. A strong green luminescence was observed at 500 nm with a bandwidth of 4240 cm −1 at temperatures lower than 60 K; then the thermal quenching occurred with increasing temperature. The thermal quenching behaviors of the luminescence intensity and the decay time could be explanined by using a simple thermal quenching model.