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Journal of Solid State Electrochemistry

, Volume 17, Issue 3, pp 607–615 | Cite as

Electrochemical determination of thermodynamic properties of DyRhO3 and phase relations in the system Dy-Rh-O

  • Kallarackel T. JacobEmail author
  • Preeti Gupta
Original Paper

Abstract

Thermodynamic properties of Dysprosium rhodite (DyRhO3) are measured in the temperature range from 900 to 1,300 K using a solid-state electrochemical cell incorporating yttria-stabilized zirconia as the electrolyte. The standard Gibbs free energy of formation of DyRhO3 with O-type perovskite structure from its components binary oxides, Dysprosia with C-rare earth structure and β-Rh2O3 with orthorhombic structure, can be represented by the equation:
$$ {{{\varDelta G_{{f\left( {ox} \right)}}^o\left( {\pm 182} \right)}} \left/ {{{\mathrm{J} ~ \mathrm{mo}}{{\mathrm{l}}^{{ - 1}}}}} \right.} = - 52710 + 3.821\left( {{{T} \left/ {\mathrm{K}} \right.}} \right). $$

By using the thermodynamic data for DyRhO3 from experiment and auxiliary data for other phases from the literature, the phase relations in the system Dy-Rh-O are computed. Thermodynamic data for intermetallic phases in the binary system Dy-Rh, required for constructing the chemical potential diagrams, are evaluated using calorimetric data available in the literature for three intermetallics and Miedema’s model, consistent with the phase diagram. The results are presented in the form of Gibbs triangle, oxygen potential–composition diagram, and three-dimensional chemical potential diagram at 1,273 K. Temperature–composition diagrams at constant oxygen partial pressures are also developed. The decomposition temperature of DyRhO3 is 1,732 (±2.5) K in pure oxygen and 1,624 (±2.5) K and in air at standard pressure.

Keywords

Solid-state electrochemical cell DyRhO3 3-D chemical potential diagram O-type perovskite structure Dy-Rh binary system Oxygen potential 

Notes

Acknowledgments

K. T. Jacob is grateful to the Indian National Academy of Engineering for support as INAE Distinguished Professor. Preeti Gupta thanks the University Grants Commission, India, for the award of Dr. D.S. Kothari Postdoctoral Fellowship.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.Department of Materials EngineeringIndian Institute of ScienceBangaloreIndia

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