Hostname: page-component-586b7cd67f-2brh9 Total loading time: 0 Render date: 2024-11-23T09:21:28.765Z Has data issue: false hasContentIssue false
  • English
  • Français

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]
Get access

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

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