Energetics of stable and metastable low-temperature iron oxides and oxyhydroxides

Journal Article · Tue Sep 01 04:00:00 EDT 1998 · Geochimica et Cosmochimica Acta

DOI:https://doi.org/10.1016/S0016-7037(98)00208-7· OSTI ID:329209

Laberty, C; Navrotsky, A ^[1]

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1. Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

The energetics of a set of synthetic iron oxides and oxyhydroxides were determined by transposed temperature drop calorimetry and high temperature solution calorimetry using sodium molybdate as a solvent at 979 K. The experiments allow the calculation of the enthalpy of formation from the elements of {gamma}-Fe{sub 2}O{sub 3} with tetragonal symmetry (812.7 {+-} 2.6 kJ/mol) and with cubic symmetry ({minus}812.3 {+-} 2.5 kJ/mol) and {beta}-FeOOH (557.6 {+-} 2.4 kJ/mol), values currently unavailable in the literature. Maghemite, {gamma}-Fe{sub 2}O{sub 3}, is 15.3 {+-} 0.9 kJ/mol less stable in enthalpy than hematite, {alpha}-Fe{sub 2}O{sub 3}.

• OSTI ID: 329209
• Journal Information: Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: 17 Vol. 62; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AQUIFERS
CALORIMETRY
ENVIRONMENTAL TRANSPORT
FORMATION HEAT
IRON HYDROXIDES
IRON OXIDES
SOILS
STABILITY