ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The use of thermodynamic data in the calculation of limiting oxygen pressures for the existence of ternary oxides is demonstrated in the case of LaMO3 and La2MO4 (M=Mn, Fe, Co, Ni or Cu) compounds using the literature data on the relevant chemical equilibria. The standard Gibbs' energy of formation, ΔG f 0 , of LaCuO3 is estimated from the values of ΔG f 0 of the other LaMO3 compounds calculated from the literature and is given as $$\left( {\Delta G_{{\text{f,LaCuO}}_{\text{3}} }^{\text{0}} } \right)$$ (kJ mol−1)= −1095.0+0.2351 T (K). The validity of this expression is qualitatively verified with the help of experimental conditions reported in the literature for the synthesis of this compound. Similar considerations are used to predict values of 0.03 and 30 atm to be the oxygen pressure range for the existence of a quarternary compound, YBa2Cu3O9−y at 1273 K. The superconducting transition temperature, T c, is qualitatively predicted to show a maximum for the sample annealed under an oxygen pressure in the range 1 to 30 atm at 1273 K.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00547444
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