Effect of Heat Treatment on the Color of Yellow-Green Sphene and Its Color-Causing Mechanism.
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| Title: | Effect of Heat Treatment on the Color of Yellow-Green Sphene and Its Color-Causing Mechanism. |
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| Authors: | Song, Zi-Xiong1 (AUTHOR), Guo, Qing-Feng1 (AUTHOR) qfguo@cugb.edu.cn, Liao, Li-Bing2 (AUTHOR) clayl@cugb.edu.cn |
| Source: | JOM: The Journal of The Minerals, Metals & Materials Society (TMS). Jul2025, Vol. 77 Issue 7, p5182-5191. 10p. |
| Subjects: | Sphene, Valence fluctuations, Heat treatment, Gems & precious stones, Ions |
| Abstract: | Heat treatment is a widely employed method for improving gemstone color. In this study, yellow-green sphene was subjected to heat treatment in both oxidizing and reducing atmospheres. By comparing the composition, structure, and ion valence of samples before and after heat treatment, we analyzed the coloration mechanism of sphene and identified the optimal heat treatment conditions. The results indicate that the change in the valence state of Fe during the heating process is the primary reason for the color change of sphene. In an oxidizing atmosphere, some Fe2+ ions were oxidized to Fe3+, increasing the yellow tone of sphene. Conversely, in a reducing atmosphere, some Fe3+ ions were reduced to Fe2+, decreasing the yellow tone. Under an oxidizing atmosphere, we achieved a highly saturated sphene body color favored in the market, providing valuable insights and experimental data for further research on sphene heat treatment. [ABSTRACT FROM AUTHOR] |
| Copyright of JOM: The Journal of The Minerals, Metals & Materials Society (TMS) is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Abstract: | Heat treatment is a widely employed method for improving gemstone color. In this study, yellow-green sphene was subjected to heat treatment in both oxidizing and reducing atmospheres. By comparing the composition, structure, and ion valence of samples before and after heat treatment, we analyzed the coloration mechanism of sphene and identified the optimal heat treatment conditions. The results indicate that the change in the valence state of Fe during the heating process is the primary reason for the color change of sphene. In an oxidizing atmosphere, some Fe2+ ions were oxidized to Fe3+, increasing the yellow tone of sphene. Conversely, in a reducing atmosphere, some Fe3+ ions were reduced to Fe2+, decreasing the yellow tone. Under an oxidizing atmosphere, we achieved a highly saturated sphene body color favored in the market, providing valuable insights and experimental data for further research on sphene heat treatment. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 10474838 |
| DOI: | 10.1007/s11837-025-07308-z |
