Solid State Electrochemical Study of Phase Equilibria and Thermodynamics of the Ternary System Y-Fe-O at Elevated Temperatures
Open Access
- 1 April 1979
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung A
- Vol. 34 (4) , 430-436
- https://doi.org/10.1515/zna-1979-0404
Abstract
A solid state galvanic cell technique has been employed to determine the phase diagram of the ternary system Y-Fe-O in the temperature range from 900 to 1250 °C. Only electrical quantities need to be measured and the samples do not have to be quenched. YFeO3 and Y3Fe5O12 exist over the entire temperature range, whereas the third ternary compound YFe2O4-x is only thermodynamically stable above 1010 ± 9 °C. Above 1078 ± 15 °C YFe2O4-x comes into equilibrium with Y2O3. With the same experimental arrangement the standard Gibbs free energies of formation ⊿G f 0 of the ternary compounds YFeO3, Y3Fe5O12 and YFe2O4 have been determined to be -1366.0 + 0.2525 X T kJ/mol (1173 ≦ T [K] ≦ 1523), - 4912.2 +0.9990 X T kJ/mol (1173≦T[K] ≦ 1523) and -1615.9 + 0.3068 x T kJ/mol (1283≦T[K] ≦ 1523) as functions of the temperature, respectivelyKeywords
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