The Oxygen Potentials in the Y2O3-BaO-CuOx System
- 1 November 1989
- journal article
- Published by IOP Publishing in Japanese Journal of Applied Physics
- Vol. 28 (11A) , L1963-1966
- https://doi.org/10.1143/jjap.28.l1963
Abstract
The oxygen potential for some chosen four and three-phase combinations has been measured at 750–1000°C using solid ZrO2+CaO electrolyte. On the basis of log P O2 values, the Gibbs energies of reactions for many possible reactions in the system were obtained. The reactions with the Y2BaO4 on the left sides exhibit negative entropy due to decomposition of Y2BaO4 below about 850°C. The positive entropy for several reactions clearly indicates that ternary cuprates such as Y2BaCuO5, YBa2Cu3O x , YBa4Cu3O x and Y3Ba8Cu5O x are entropy-stabilized compounds. These cuprates become increasingly less stable with decreasing temperature and on cooling there are temperature limits below which these cuprates are metastable.Keywords
This publication has 1 reference indexed in Scilit:
- Phase relation and superconductivity in the oxygen nonstoichiometric system, Ba2YCu3OxMaterials Research Bulletin, 1987