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Heat capacities and thermodynamic properties of annite (aluminous iron biotite)

B. S. Hemingway·R. A. Robie
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Abstract

The heat capacities have been measured between 7 and 650 K by quasi-adiabatic calorimetry and differential scanning calorimetry. At 298.15 K and 1 bar, the calorimetric entropy for our sample is 354.9??0.7 J/(mol.K). A minimum configurational entropy of 18.7 J/(mol.K) for full disorder of Al/Si in the tetrahedral sites should be added to the calorimetric entropy for third-law calculations. The heat capacity equation [Cp in units of J/mol.K)] Cp0 = 583.586 + 0.075246T - 3420.60T-0.5 - (4.4551 ?? 106)T-2 fits the experimental and estimated heat capacities for our sample (valid range 250 to 1000 K) with an average deviation of 0.37%. -from Authors

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B. S. Hemingway, R. A. Robie. 1990. Heat capacities and thermodynamic properties of annite (aluminous iron biotite). https://pubs.usgs.gov/publication/70016292

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