Amorphous/Crystalline (A/C) Thermodynamic 鈥淩ules of Thumb鈥? Estimating Standard Thermodynamic Data for Amorphous Materials Using Standard Data for Their Crystalline Counterparts

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• 作者：Diane Holland ; H. Donald Brooke Jenkins
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：May 7, 2012
• 年：2012
• 卷：51
• 期：9
• 页码：5368-5376
• 全文大小：311K
• 年卷期：v.51,no.9(May 7, 2012)
• ISSN：1520-510X

文摘

Standard thermochemical data (in the form of 螖b>fb>H掳 and 螖b>fb>G掳) are available for crystalline (c) materials but rarely for their corresponding amorphous (a) counterparts. This paper establishes correlations between the sets of data for the two material forms (where known), which can then be used as a guideline for estimation of missing data. Accordingly, 螖b>fb>H掳(a)/kJ mol^鈥? 鈮?0.993螖b>fb>H掳(c)/kJ mol^鈥? + 12.52 (R² = 0.9999; n = 50) and 螖b>fb>G掳/kJ mol^鈥? 鈮?0.988螖b>fb>H掳(c)/kJ mol^鈥? + 0.70 (R² = 0.9999; n = 10). Much more tentatively, we propose that S掳b>298b>(c)/J K^鈥? mol^鈥? 鈮?1.084S掳b>298b>(c)/J K^鈥? mol^鈥? + 6.54 (R² = 0.9873; n = 11). An amorphous hydrate enthalpic version of the Difference Rule is also proposed (and tested) in the form [螖b>fb>H掳(Mb>pb>Xb>qb>路nHb>2b>O,a) 鈥?螖b>fb>H掳(Mb>pb>Xb>qb>,a)]/kJ mol^鈥? 鈮?螛b>Hfb>n 鈮?鈭?02.0n, where Mb>pb>Xb>qb>路nHb>2b>O represents an amorphous hydrate and Mb>pb>Xb>qb> the corresponding amorphous anhydrous parent salt.