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Enthalpies of formation of CaAl4O7 and CaAl12O19 (hibonite) by high temperature, alkali borate solution calorimetryEnthalpies of formation were determined for two calcium aluminate phases, CaAl4O7 and CaAl12O19, using high-temperature alkali borate solution calorimetry. The aluminates were synthesized by multiple-cycle heating and grinding stoichiometric mixtures of CaCO3 and Al2O3, and the products were characteized by X-ray diffraction and SEM microbeam analysis. The data on impurities (CaAl4O7 was found to be about 89.00 percent pure by weight and the CaAl12O19 samples about 91.48 percent pure) were used to correct the heat of solution values of the synthetic products. The enthalpies of formation, at 1063 K, from oxides, were found to be equal to -(25.6 + or - 4.7) kJ/g.f.w. for CaAl4O7 and -(33.0 + or - 9.7) kJ/g.f.w. for CaAl12O19; the respective standard enthalpies of formation from elements, at 298 K, were estimated to be -4007 + or - 5.2 kJ/g.f.w. and -10,722 + or - 12 kJ/g.f.w.
Document ID
19880060623
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Geiger, C. A.
(Chicago Univ. Chicago, IL, United States)
Kleppa, O. J.
(Chicago Univ. Chicago, IL, United States)
Grossman, L.
(Chicago, University IL, United States)
Mysen, B. O.
(Carnegie Institution of Washington Washington, DC, United States)
Lattimer, J. M.
(New York, State University Stony Brook, United States)
Date Acquired
August 13, 2013
Publication Date
June 1, 1988
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 52
ISSN: 0016-7037
Subject Category
Lunar And Planetary Exploration
Accession Number
88A47850
Funding Number(s)
CONTRACT_GRANT: NAG9-54
CONTRACT_GRANT: NSF CHE-87-00937
CONTRACT_GRANT: NSF CHE-83-20560
Distribution Limits
Public
Copyright
Other

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