Thermodynamic stability of K β-alumina

Kale, G. M. ; Jacob, K. T. (1999) Thermodynamic stability of K β-alumina Metallurgical and Materials Transactions B, 20 (5). pp. 687-691. ISSN 1073-5615

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The activity of K2O in a mixture of α-alumina and Kβ-alumina has been determined using the solid state galvanic cell: Ta, Bi-5 mol pct K // α-alumina + Kβ-alumina // In + In2O3, Ta in the temperature range 600 to 1000 K. The cell is written such that the right hand electrode is positive. The solid electrolyte consisted of a dispersion of α-alumina (~15 vol pct) in a matrix of Kβ-alumina. The emf of the cell was found to be reversible and to vary linearly with tem-perature. From the emf and auxiliary data on In2O3 and K2O from the literature, the activity of K2O in the two-phase mixture is obtained as log aK2O = 2.368 -20,850/T(K) (±0.015) The standard free energy of formation of Kβ-alumina from component oxides is given by K2O (s) + 9.5 β-Al2O3 (s) ΔK2O·9.5A12O3 (s) ΔG° = -398,920 + 45.01 T(K) (±1000) J mol-1.

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Source:Copyright of this article belongs to Springer-Verlag.
ID Code:13045
Deposited On:11 Nov 2010 07:01
Last Modified:16 May 2016 22:16

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