Thermodynamic study at high temperature of the superconducting system YBa2Cu3Oz with 6 <z<7
- 1 December 1987
- journal article
- Published by Springer Nature in Journal of Materials Research
- Vol. 2 (6) , 757-761
- https://doi.org/10.1557/jmr.1987.0757
Abstract
The YBa2Cu3Oz system has been investigated by thermogravimetry in a controlled partial oxygen pressure PO2 ranging from 105-10 Pa. A compound with z = 6.290 was prepared at T = 950°C and PO2 = 105 Pa and identified as a metastable β phase. Subsequent isothermal or isobar phase stability studies were performed. This β phase has a narrow metastability domain 6.25 PO2, the β phase transforms irreversibly into an α phase characterized by large deviations 7—x from stoichiometry. Near the stoichiometry z = 7, the structure of the a phase is orthorhombic, and fully ionized vacancies are likely to be predominant. By decreasing the PO2, the β phase transforms into a new phase with a lower oxygen content (z < 6.1).Keywords
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