نوع مقاله : پژوهشی
نویسندگان
1 دانشگاه شهید بهشتی دانشکده علوم زمین
2 مرکز گوهرشناسی دانشگاه شهید بهشتی، دانشکده علوم زمین
3 دانشکده مواد و متالورژی، دانشگاه علم و صنعت ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Synthetic play-of-color opal produced from TEOS with 200–250 µm spheres was thermally analyzed and compared with a natural Ethiopian opal. Below 180 °C, the synthetic samples show a 6.80–10.74% mass loss due to the release of surface and interstitial water. Bound water and free silanol groups are removed between 270 and 430 °C. An exothermic peak at 400–450 °C, attributed to the decomposition of residual ethoxy groups from carbon-based precursors, appears only in the synthetic opal. Structural silanols are eliminated above 1000 °C, concurrent with collapse of the opal framework. Overall mass-loss trends in both samples are similar. The results indicate that stabilizing synthetic opal requires complete removal of volatile components and subsequent filling of pore spaces with stable materials, and the thermal ranges necessary for these processes can be clearly defined.
کلیدواژهها [English]
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