Relative thermodynamic stabilities of constituent oxides of highTc superconductors
A thermodynamic scale of the relative stabilities of constituent oxides can help the choice of stoichiometric multi-component compositions and can provide guidance for judicious selection of heat-treatment conditions for high-Tc superconductors. A thermodynamic analysis was undertaken to study Y2O3-BaO-CuO, BaO-K2O-Bi2O3 and La2O3-SrO-NiO systems. The relative stability of the oxides was expressed in terms of two ratios,Sv andSp computed using free-energy of formation and vapour pressure data. CuO, Bi2O3 and NiO were taken as reference oxides for YBa2Cu3O7\t-\gd, Ba0·6K0·4BiO3 and La1·9Sr0·1NiO4 respectively. Thermodynamically, the reference oxide was found to be the least stable amongst the constituent oxides in each of these systems.
SK Sundaram1 2
Volume 42 | Issue 6
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