Peritectic decomposition of barium-yttrium cuprate YBa₂Cu₃O_x

V.V.Prisedsky, E.I.Volkova, I.A.Udodov

Donetsk State Technical University, 38 Artema St., 340000, Donetsk, Ukraine

Received April 7, 1998

By the method of X-ray diffraction analysis together with scanning electron microscopy, electron microprobe and thermal analysis scanning electron microscopy, electron microprobe and thermal analysis have been used to study thermal decomposition of barium-yttrium cuprate YBa₂Cu₃O_x above 900 ^oC in two ambients: air and vacuum (residual p(O₂) = 700 Pa). In air, YBa₂Cu₃Ox undergoes peritectic decomposition at 1020^o into Y₂BaCuO₅ and melt of barium and monovalent copper oxides. Y₂BaCuO₅ remains stable up to 1270^o and at that temperature decomposes to Y₂O₃.
In vacuum, at p(O₂) › 700Pa, complete peritectic decomposition of 123 phase takes place at 965^o and is preceded, tarting from 925^o, by nonequilibriums partial decomposition of YBa₂Cu₃O_x into Y₂BaCuO₅, YBa₃Cu₂O_y and BaCu₂O₂.

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