Enthalpy of formation of zircon

Journal Article · Mon Jun 01 00:00:00 EDT 1992 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1992.tb04205.x· OSTI ID:7048183

Ellison, A J.G. ^[1]; Navrotsky, A ^[2]

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1. Materials Science Div., Argonne National Lab., Argonne, IL (US)
2. Dept. of Geological and Geophysical Sciences, Princeton Univ., Princeton, NJ (US)

Using high-temperature solution calorimetry in molt 2PbO {center dot} B{sub 2}O{sub 3}, the enthalpy of reaction of the formation of zircon, ZrSiO{sub 4}, from its constituent oxides has been determined: {Delta}{sub 4}H{sub 977}(ZrSiO{sub 4}) = {minus}27.9 ({plus minus}1.9) kJ/mol. With previously reported data for the heat contents of ZrO{sub 2} SiO{sub 2} and ZrSiO{sub 4} and standard-state enthalpies of formation of ZrO{sub 2} and SiO{sub 2}, we obtain {Delta}{sub f}H{sub 298}{degrees}. (ZrSiO{sub 4}) = {minus}2034.2 ({plus minus}3.1) kJ/mol and {Delta}{sub t}G{sub 298}{degrees} (ZrSiO{sub 4}) = {minus}1919.8 kJ/mol. The free energy value is in excellent agreement with a range previously estimated from solid-state reaction equilibria. At higher temperature also the data are in close agreement with existing data, though the data sets diverge somewhat with increasing T. In this paper the limitations of the data for predicting the breakdown temperature of zircon into its constituent oxides are discussed.

• DOE Contract Number: FG02-85ER13437
• OSTI ID: 7048183
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 75:6; ISSN 0002-7820; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
BORON COMPOUNDS
BORON OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
DISPERSIONS
ENERGY
ENTHALPY
FREE ENERGY
KINETICS
LEAD COMPOUNDS
LEAD OXIDES
MINERALS
MIXTURES
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PHYSICAL PROPERTIES
REACTION KINETICS
SILICATE MINERALS
SILICON COMPOUNDS
SILICON OXIDES
SOLID SOLUTIONS
SOLUTIONS
THERMODYNAMIC PROPERTIES
ZIRCON