アフリカ産の天然ルビーの色相改善

概要

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Color enhancement of African rubies with dark red was carried out by heat treatment and hydrothermal treatment respectively. The heat treatment brought about an adverse effect causing the color to be deteriorated. However, the hydrothermal treatment enhanced its color and clarity. The hydrothermal treatment conditions for the color enhancement of African rubies were a reaction temperature of 450℃ for 48 hrs under a pressure of 375 atm, using a solvent of 0.9M Na_2CO_3-1M K_2CO_3. As the results of characteristics for African rubies obtained under these conditions, it was known that the amount of Cr^<3+>, Fe^<3+>, Ti^<4+> was reduced after the hydrothermal treatment from the ICP/MS and XRF analyses. Also, it was found that the red color from the colorimeter analyses was getting lighter. These results were consistent with the PL analysis showing that the intensity of the luminescence peak generated by the electron transition of Cr^<3+> ion became lower after the hydrothermal treatment compared with the non-treated rubies.
2008-03-30