Formation enthalpy of ThSiO4 and enthalpy of the thorite → huttonite phase transition

Lena Mazeina, Sergey V. Ushakov, Alexandra Navrotsky, Lynn A. Boatner

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


The standard enthalpy of formation of thorite and huttonite and the enthalpy of the phase transition between these polymorphs were determined using high-temperature oxide melt solution calorimetry and transposed temperature drop calorimetry. Standard enthalpies of formation of thorite and huttonite are reported for the first time and are -2117.6 ± 4.2 kJ/mol and -2110.9 ± 4.7 kJ/mol, respectively. Based on our measurements, thorite and huttonite are metastable relative to SiO2 (quartz) and ThO2 (thorianite) at standard conditions, but are presumably stabilized at high temperature by the entropy contribution. Based on the measured enthalpy of the thorite-huttonite phase transition of 6.7 ± 2.5 kJ/mol, a dP/dT slope for the transformation was calculated as -1.21 ± 0.45 MPa/K.

Original languageEnglish (US)
Pages (from-to)4675-4683
Number of pages9
JournalGeochimica et Cosmochimica Acta
Issue number19
StatePublished - Oct 1 2005
Externally publishedYes

ASJC Scopus subject areas

  • Geochemistry and Petrology


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