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Direct measurements of fusion and phase transition enthalpies in lanthanum oxide

Published online by Cambridge University Press:  09 February 2011

Sergey V. Ushakov  and
Alexandra Navrotsky
Sergey V. Ushakov*
Affiliation:
Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, California 95616
Alexandra Navrotsky
Affiliation:
Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, California 95616
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Enthalpies of high-temperature phase transitions and fusion in lanthanum oxide (La2O3) were directly measured for the first time. Three samples were prepared by laser melting, sealed in tungsten crucibles, and heated in a differential thermal analyzer calibrated by melting Al2O3. Transformation enthalpy of La2O3 from A to H phase is 23 ± 5 kJ/mol at 2046 ± 5 °C and from H to X phase is 17 ± 5 kJ/mol at 2114 ± 5 °C. Lanthanum oxide melts at 2301 ± 10 °C, with enthalpy of fusion of 78 ± 10 kJ/mol.

Keywords

CalorimetryPhase EquilibriaPhase Transformation
Type
Materials Communications
Information
Journal of Materials Research , Volume 26 , Issue 7 , 14 April 2011 , pp. 845 - 847
Copyright
Copyright © Materials Research Society 2011

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References

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