Abstract
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 a-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 aK 2O = 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 α-Al2O3 (s) → K2O.9.5A12O3 (s) δG‡ = -398,920 + 45.01 T(K) (±1000) J mol-1
Similar content being viewed by others
References
K.K. Kim, J.N. Mundy, and W.K. Chen:J. Phys. Chem. Solids, 1979, vol. 40, pp. 743–55.
I. Iami and M. Harata:Japan. J. Appl. Phys., 1972, vol. 11, pp. 180–85.
J.L. Braint and G.C. Farrington:J. Solid State Chem., 1980, vol. 33, pp. 385–90.
Y.-F.Y. Yao and J.T. Kummer:J. Inorg. Nucl. Chem., 1967, vol. 29, pp. 2453–75.
C.A. Beevers and S. Brohult:Z. Kristallogr., 1936, vol. 95, pp. 472–74.
R. Gee and D.J. Fray:Electrochim. Acta, 1979, vol. 24, pp. 765–67.
B. Dunn and G.C. Farrington:Mater. Res. Bull., 1980, vol. 15, pp. 1773–77.
J.T. Whiter and D.J. Fray:Solid State Ionics, 1985, vol. 17, pp. 1–6.
R.V. Kumar and D.A.R. Kay:Metall. Trans. B, 1985, vol. 16B, pp. 107–12.
R.V. Kumar and D.A.R. Kay:Metall. Trans. B, 1985, vol. 16B, pp. 295–301.
G. Rog, S. Kozinski, and A. Kozlowska-Rog:Electrochim. Acta, 1981, vol. 26, pp. 1819–21.
M. Itoh and Z. Kozuka:J. Am. Ceram. Soc, 1988, vol. 71, pp. C36-C39.
M. Rivier and A.D. Pelton:Am. Ceram. Soc. Bull., 1978, vol. 57, pp. 183–85.
K.T. Jacob:Trans. Inst. Mining Met. Sect. C, 1978, vol. 87, pp. C165-C170.
D.R. Stull and H. Prophet:Janaf Thermochemical Tables, 2nd ed., U.S. Department of Commerce, National Bureau of Standards, 1971.
A. Petric, A.D. Pelton, and M.-L. Saboungi:J. Phys. F.: Met. Phys., 1988, vol. 18, pp. 1473–81.
O.J. Kleppa and L.S. Hersh:J. Am. Chem. Soc., 1961, vol. 34, pp. 351–58.
L.S. Hersh and O.J. Kleppa:J. Am. Chem. Soc., 1965, vol. 42, pp. 1309–22.
K.T. Jacob and J.H.E. Jeffes:High Temp. High Press., 1972, vol. 4, pp. 177–81.
R.A. Robie, B.S. Hemingway, and J.R.Fisher:Thermodynamic Properties of Minerals and Related Substances at 298.15 K and 1 Bar (105 Pascals) and Higher Temperatures, Geol. Survey Bull. 1452, 1978, pp. 313 and 316.
K.T. Jacob, O.M. Sreedharan, and C. Mallika: Unpublished re- search, 1983.
F.A. Elrefaie and W.W. Smeltzer:J. Electrochem. Soc., 1981, vol. 128, pp. 1443–47.
E.W. Dewing: Quoted in Ref. 26.
D.J. Fray:Metall. Trans. B, 1977, vol. 8B, pp. 153–56.
G. Rog, S. Kozinski, and A. Kozlowska-Rog:Electrochim. Acta, 1983, vol. 28, pp. 43–45.
N.S. Choudhury:J. Electrochem. Soc., 1973, vol. 120, pp. 1663–67.
A. Dubreuil, M. Malenfant, and A.D. Pelton:J. Electrochem. Soc., 1981, vol. 128, pp. 2006–08.
M. Itoh, K. Kimura, and Z. Kozuka:Trans. Japan Inst. Metals, 1985, vol. 26, pp. 353–61.
R.J. Brisley and D.J. Fray:Metall. Trans. B, 1983, vol. 14B, pp. 435–40.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kale, G.M., Jacob, K.T. Thermodynamic stability of kΒ-alumina. Metall Trans B 20, 687–691 (1989). https://doi.org/10.1007/BF02655926
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02655926