Photoluminescence properties of a natural fluorite

抄録

Photoluminescence properties of a natural fluorite from China are investigated at temperatures of 10, 80 and 300 K. The color of the fluorite is green under the daylight and it emits bluish violet fluorescence under UV light. The band peak (423 nm) at room temperature and the vibronic structure at low temperatures show that the bluish violet fluorescence originates from Eu²⁺ ion in the fluorite. In the excitation spectrum obtained by monitoring the bluish violet fluorescence, not only the Eu²⁺ band but the Ce³⁺ band are observed as broad bands. They are attributed to the f-d electronic transitions in Eu²⁺ and Ce³⁺. It was interpreted that the excitation processes of the bluish violet fluorescence are due to the direct excitation of the Eu²⁺ ion and the energy transfer from Ce³⁺ to Eu²⁺ in fluorite. The abundance of rare-earth impurities in the fluorite was analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) after the treatment with the cation-exchange column. Relationship between the photoluminescence and rare-earth impurities is discussed.