ABSTRACT
From the discovery of the first ceramic superconductor [1] and thermoelectric oxides with attractive performances [2], much work has been performed on these materials, leading to the discovery of new families, such as the superconducting Bi2Sr2CaCu2Ox (Bi-2212) [3] or the thermoelectric Bi2Sr2Co1.8Oy (BSCO) [4]. These materials are mainly characterized by their good electrical properties in the conducting planes: Cu-O planes in the superconducting and Co-O planes in the thermoelectric ceramics, which are coincident with the crystallographic ab-planes in both cases. This feature can be exploited in the development of commercial applications for these ceramics, with improved electrical properties, when an adequate grain orientation is produced using texturing techniques. The Bi-2212 superconductor and BSCO thermoelectric materials have demonstrated that they are suitable for many practical applications when they are properly processed in order to produce well oriented grains [5, 6]. Among many
techniques used successfully to produce well textured materials [7-11], the directional growth from the melt by the laser floating zone (LFZ) method has demonstrated to be a very useful technique for producing well textured Bi-2212 and BSCO rods at high growth rates [12-14]. The materials textured by this technique, have very well aligned crystals, with their c-axis perpendicular to the current flow direction, with low angle tilt grain boundaries, obtaining a good electrical connectivity between grains. Moreover, they show very interesting properties, quantified by the critical current density (Jc) in the case of Bi-2212 and the thermoelectric power factor (PF) for the BSCO materials that allow developing practical applications.
