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Phase Relations in the System La-Rh-O and Thermodynamic Properties of LaRhO3

Jacob, Thomas K and Waseda, Yoshio (1995) Phase Relations in the System La-Rh-O and Thermodynamic Properties of LaRhO3. In: Journal of the American Ceramic Society, 78 (2). pp. 440-444.

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1151-...


Phase relations in the system La-Rh-O at 1223 Ii have been determined by examination of equilibrated samples by optical and scanning electron microscopy, powder X-ray diffraction (XRD), and energy-dispersive analysis of X-rays (EDAX). Only one ternary oxide, LaRhO3, with distorted orthorhombic perovskite structure (Pbnm, a = 0.5525, b = 0.5680, and c = 0.7901 nm) was identified. The alloys and intermetallics along the La-Rh binary are in equilibrium with La2O3. The thermodynamic properties of LaRhO3 were determined in the temperature range 890 to 1310 K, using a solid-state cell incorporating yttria-stabilized zirconia as the electrolyte. A new four-compartment design of the emf cell was used to enhance the accuracy of measurement. For the reaction 1/2La(2)O(3) + 1/2Rh(2)O(3) --> LaRhO3, Delta G degrees = - 70 780 + 4.89T (+/- 90) J.mol(-1) The compound decomposes on heating to a mixture of La2O3, Ph and O-2. The calculated decomposition temperatures are 1843 (+/- 5) K in pure O-2 and 1728 (+/- 5) K in air at a pressure of 1.01 x 10(5) Pa. The phase diagrams for the system La-Rh-O at different partial pressures of oxygen are calculated from the thermodynamic information.

Item Type: Journal Article
Publication: Journal of the American Ceramic Society
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 23 May 2011 10:15
Last Modified: 23 May 2011 10:15
URI: http://eprints.iisc.ac.in/id/eprint/37857

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