Crystal growth orientation and microstructure of Y0.9Ca0.1Ba2Cu3O7−δ melt grown bars

The crystal growth direction of Ca-doped Y123 superconductor material processed by a floating zone method is investigated. Basically, the process consists in melting partially a Y123/Y211 bar and in growing Y123 material by translating the molten zone owing to the sample bar displacement across the micro-wave furnace. Several Ca-doped or undoped bars have been processed. Textured quality, microstructure and crystal growth direction are investigated for each bar. The most attractive result concerns the crystal orientation of the calcium-doped samples: they exhibit (ab) planes almost aligned with respect to the bar axis direction. Such orientation is one of the most appropriate conditions to transport a high current density. According to our knowledge, such orientation is obtained for the first time without seeding technique and with a satisfying reliability using a vertical floating zone method from micro-wave furnace.