Microstructural characterization of quenched melt-textured YBa 2 Cu 3 O 7−δ materials

The microstructure of YBa 2 Cu 3 O 7−δ (YBCO) materials, melt-textured in air and quenched from the temperature range 900–;990 °C, has been characterized using a combination of x-ray diffractometry, optical microscopy, scanning electron microscopy, transmission electron microscopy, and energy dispersive x-ray spectrometry. BaCu 2 O 2 and BaCuO 2 were found to coexist in samples quenched from the temperature range 920–960 °C. The formation of BaCu 2 O 2 preceded the formation of YBCO. Once the YBCO had formed, BaCu 2 O 2 was present at the solidification front filling the space between nearly parallel platelets of YBCO. Large Y 2 BaCuO 2 particles at the solidification front appeared divided into smaller ones as a result of their dissolution in the liquid that quenched as BaCu 2 O 2 .