Thermodynamic properties of oxygen in RE-O (RE = Gd, Tb, Dy, Er) solid solutions

Kasai, E and Saito, F and Waseda, Y and Jacob, KT and Hirota, K and Okabe, TH (1998) Thermodynamic properties of oxygen in RE-O (RE = Gd, Tb, Dy, Er) solid solutions. In: Journal of Alloys and Compounds, 279 (2). pp. 184-191.

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Abstract

The oxygen potentials of four rare-earth metal – oxygen (RE–O: RE=Gd, Dy, Tb, Er) solid solutions have been measured by equilibration with yttrium – oxygen (Y–O) and titanium – oxygen (Ti–O) solid solutions. Rare-earth metal, yttrium and titanium samples were immersed in calcium-saturated CaCl2 melt at temperatures between 1093 and 1233 K. Homogeneous oxygen potential was established in the metallic samples through the fused salt, which contains some dissolved CaO. The metallic samples were analyzed for oxygen after quenching. The oxygen potentials of RE–O solid solutions were determined using either Y–O or Ti–O solid solution as the reference. This method enabled reliable measurement of extremely low oxygen potentials at high temperature (circa pO2=10−48 atm at 1173 K). It was found that the oxygen affinity of the metals decreases in the order: Y>Er>Dy>Tb>Gd>Ti. Values for the standard Gibbs energy of solution of oxygen in RE metals obtained in this study, permit assessment of the extent of deoxidation that can be achieved with various purification techniques. It may be possible to achieve an oxygen level of 10 mass ppm using an electrochemical deoxidation method.

Item Type:	Journal Article
Publication:	Journal of Alloys and Compounds
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Rare-earth metals;Gadolinium; Terbium;Dysprosium; Erbium; Yttrium;Solution of oxygen;Thermodynamics;Gibbs energy; Deoxidation
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	01 Mar 2012 06:11
Last Modified:	01 Mar 2012 06:11
URI:	http://eprints.iisc.ac.in/id/eprint/42694

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