High temperature X-ray studies of mayenite synthesized using the citrate sol-gel method

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• 作者：Sabina N. Ude ; Claudia J. Rawn ; Roberta A. Peascoe ; Melanie J. Kirkham ; Gregory L. Jones ; E. Andrew Payzant
• 关键词：B. High temperature X-ray ; A. Citrate sol&ndash ; gel ; C. Thermal expansion ; B. Scanning electron microscopy
• 刊名：Ceramics International
• 出版年：January, 2014
• 年：2014
• 卷：40
• 期：1_part_PA
• 页码：1117-1123
• 全文大小：2349 K

文摘

Room temperature and high temperature x-ray powder diffraction and differential thermal analysis/thermo-gravimetric analysis (DTA/TGA) have been used to characterize the phase evolution of bulk mayenite (Ca₁₂Al₁₄O₃₃) prepared using the citrate sol-gel method. These studies have shown that single phase mayenite forms at 900 掳C in air after approximately three hours. High temperature x-ray powder diffraction data show that when firing in air at temperatures 600 掳C and below only amorphous content is observed; above 600 掳C CaCO₃ is the first phase to crystallize. For samples quenched at 800 掳C and evaluated using room temperature x-ray powder diffraction mayenite, CaAl₂O₄, and CaCO₃ were present. High temperature x-ray diffraction data collected while firing in 4% H₂/96% N₂ reveals that CaCO₃ does not form and Ca₁₂Al₁₄O₃₃ starts to form around 850 掳C. DTA/TGA data collected either in a nitrogen environment or air on samples synthesized using the citrate gel method support the complete decomposition of metastable phases and the formation of mayenite at 900 掳C, although the phase evolution is different depending on the environment.