Coloring of synthetic fluorite

A synthetic fluorite of the Harshaw Chemical Company is analyzed for rare earth elements, yttrium, and sodium. Samples of this fluorite are irradiated with X-rays, ?-rays, neutrons, electrons, protons, and ?-particles at different energies, and their absorption spectra are analyzed. Analyzing the thermal bleaching of these radiation-coloured fluorites shows that both, impurities and radiation play a part in the coloration of synthetic fluorite. However, the main contribution comes from the radiation induced lattice defects. In the visible region spectra, the colour centre of the 5800 to 5900 Å absorption band is probably mainly related with large aggregates of F-centres. The 5450 and the 5300 Å absorption bands are mainly related to monovalent and divalent ion impurities and their association with lattice defects. The 3800 Å absorption band seems to be related with F-centre aggregates. However, the contribution from the rare earth elements related complex color centres also plays some part for the production of this absorption band. These results indicate that the color centres of different origin can absorb light at the same wavelength. Copyright © 1980 WILEY-VCH Verlag GmbH & Co. KGaA