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Phase chemistry of the system Nb-Rh-O

Jacob, KT and Gupta, Preeti and Vinay, M and Waseda, Y (2013) Phase chemistry of the system Nb-Rh-O. In: Journal of Solid State Chemistry, 202 . pp. 234-240.

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Official URL: http://dx.doi.org/10.1016/j.jssc.2013.03.056


Phase relations in the system Nb-Rh-O at 1223 K were investigated by isothermal equilibration of eleven compositions and analysis of quenched samples using OM, XRD, SEM and EDS. The oxide phase in equilibrium with the alloy changes progressively from NbO to NbO2, NbO2.422 and Nb2O5-x with increasing Rh. Only one ternary oxide NbRhO4 with tetragonal structure (a=0.4708 nm and c=0.3017 nm) was detected. It coexists with Rh and Nb2O5. The standard Gibbs energy of formation of NbRhO4 from its component binary oxides measured using a solid-state electrochemical cell can be represented by the equation; Delta G(f,ox)(o)(J/mol) = -38,350 + 5.818 x T(+/- 96) Constructed on the basis of thermodynamic information of the various alloy and oxide phases are oxygen potential diagram for the system Nb-Rh-O at 1223 K and temperature-composition diagrams at constant partial pressures of oxygen.

Item Type: Journal Article
Publication: Journal of Solid State Chemistry
Publisher: Elsevier Science
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: NbRhO4; Gibbs Free Energy; Enthalpy; Entropy; Oxygen Potential; System Nb-Rh
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 06 Aug 2013 11:32
Last Modified: 06 Aug 2013 11:32
URI: http://eprints.iisc.ac.in/id/eprint/46912

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