Single-domain HTc superconducting materials synthesis: BaZrO3 substrates as a tool for optimized systems

Large Dy-123 single-domains have been grown by the top-seeding melt-textured growth technique on yttrium oxide substrates. The main obstacles in fabricating such "single grain" 123 superconducting samples are discussed, i.e. (i) the dissolution of the seed during the melting and the peritectic cooling stages (ii) the nucleation of subsidiary 123 grains at the compact/substrate interface. Such secondary nucleation process prevents the single grain from growing further. Solutions are suggested as for example by considering the use of a modified coating. BaZrO3 displays a strong inertia in barium cuprate fluxes which suggests to use it as a very promising candidate for buffer layer in between the 123 compact and the furnace "environment". In order to provide such "high quality" sufficiently dense BaZrO3 coatings, soft solution routes have been investigated. Advantages of these are a lower calcination temperature and the production of very homogeneous and fine monodisperse powders. The influence of the synthesis conditions on the properties of BaZrO3 and on the sintering process is thus reported.