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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

REFERENCES

1.Goldschmidt, V.M., Ulrich, F., and Barth, T.: Geochemical distribution laws of the elements. IV. The crystal structure of the oxides of the rare earth metals. Skrifter utgit av det norske Videnskap-Akademi i Oslo. (I) Matem.-Naturvid. Klasse 5 (1925).Google Scholar
2.Aldebert, P. and Traverse, J.P.: Neutron diffraction study of the high temperature structures of lanthanum oxide and neodymium oxide. Mater. Res. Bull. 14, 303 (1979).CrossRefGoogle Scholar
3.Foex, M. and Traverse, J.P.: Investigations about crystalline transformation in rare earths sesquioxides at high temperatures. Revue Internationale des Hautes Temperatures et des Refractaires 3, 429 (1966).Google Scholar
4.Coutures, J.P. and Rand, M.H.: Melting temperatures of refractory oxides: Part II. Lanthanoid sesquioxides. Pure Appl. Chem. 61, 1461 (1989).CrossRefGoogle Scholar
5.Zinkevich, M.: Thermodynamics of rare earth sesquioxides. Prog. Mater. Sci. 52, 597 (2007).CrossRefGoogle Scholar
6.Grundy, A.N., Hallstedt, B., and Gauckler, L.J.: Thermodynamic assessment of the lanthanum-oxygen system. J. Phase Equilib. 22, 105 (2001).CrossRefGoogle Scholar