TY - JOUR
T1 - Formation enthalpy of ThSiO4 and enthalpy of the thorite → huttonite phase transition
AU - Mazeina, Lena
AU - Ushakov, Sergey V.
AU - Navrotsky, Alexandra
AU - Boatner, Lynn A.
N1 - Funding Information:
We thank K. B. Helean for help with solution calorimetry on the initial stage of the project and Y. Moriya for the help with high-temperature drop experiments and J. M. Montel for fruitful correspondence. The authors are also grateful to J. Cheng, S. Deore, C. Meares, and M. Wang for their help on different stages of the project. This work was supported by the United States Department of Energy (DOE, grant DEFG0397SF14749).
PY - 2005/10/1
Y1 - 2005/10/1
N2 - 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.
AB - 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.
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U2 - 10.1016/j.gca.2005.03.053
DO - 10.1016/j.gca.2005.03.053
M3 - Article
AN - SCOPUS:26844530937
SN - 0016-7037
VL - 69
SP - 4675
EP - 4683
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 19
ER -