Peritectic decomposition of barium-yttrium cuprate YBa2Cu3Оx

Abstract

Precision X-ray diffraction analysis together with scanning electron microscopy, electron microprobe and thermal analysis have been used to study thermal decomposition of barium-yttrium cuprate YBa2Cu3Оx above 900°C in two ambients: air and vacuum (residual p(02) ~ 700 Pa. In air, YBa2Cu3Оx undergoes peritectic decomposition at 1020°C into Y2BaCu05 and melt of barium and monovalent copper oxides. Y2BaCuО5 remains stable up to 1270°C and at that temperature decomposes to Y2О3. In vacuum, at p(02) = 700 Pa, complete peritectic decomposition of 123 phase takes place at 965°C and is preceded, starting from 925°C, by nonequilibrium par tial decomposition of YBa2Cu3Оx into Y2BaCuО5, YBa3Cu2Оy and BaCu2О2.