Mineralogy and Luminescence Characteristics of Scheelite from Xuebaoding, Sichuan Province, China

In this study, the conventional mineralogical tests, LA-ICP-MS and photoluminescence spectroscopy (PL spectroscopy) tests were carried out on the scheelite in the Xuebaoding area (Pukouliang, Sandaoqi, Shuijingzhen, Wuzhutang) of Sichuan Province, China, aiming to obtain its chemical compositions, and mineralogy and luminescence characteristics. The CaWO₄ polycrystals doped with different proportions of Sm, Eu and Dy elements were synthesized by high temperature solid phase method, and their photoluminescence spectra were analyzed to explore the effects of Sm, Eu and Dy elements on their red fluorescence. The results showed that under the irradiation of medium-wave ultraviolet light (310 nm), the fluorescence colour of the scheelite samples from Xuebaoding area of Sichuan is divided into red and light-yellow. The chemical composition test results showed that the samples contain trace elements such as Sr, Nb, Mn, Mo, and rare earth elements (REE). The overall content of REE (335.8-2 243.0 μg/g) and Sr element (126.3-5 188.2 μg/g) is high. The Nb, Mn, and Mo elements enriched in the yellowish fluorescence region indicate that Mn, Mo, and Nb in the scheelite can increase the fluorescence emission intensity of the trivalent rare earth ion (RE³⁺) as an activator.The PL spectra showed that the red fluorescence is mainly contributed by Sm³⁺ and Eu³⁺, following by Dy³⁺, Tb³⁺ and Pr³⁺. The light-yellow fluorescence is mainly caused by Dy³⁺, following by Sm³⁺ and Eu³⁺. By analyzing the PL spectra of synthetic scheelite, it was concluded that Dy³⁺ is a sensitizer for Sm³⁺ and Eu³⁺, and Dy³⁺ enhances the fluorescence emission intensity of Sm³⁺ more obviously, especially the ⁴G_5/2→ ⁶H_7/2 transition (580-620 nm) of Sm³⁺.In the natural scheelite, Dy³⁺ hinders the energy transfer of Sm³⁺→Eu³⁺ and the strongest emission peak of Sm³⁺ in some samples changes from ⁴G_5/2→ ⁶H_9/2 transition (630-660 nm) to ⁴G_5/2→ ⁶H_7/2 transition (580-620 nm).