Speaker
Description
The magnet-scientific method has been adopted for fabricate grain oriented materials in these 20 years using superconducting magnets with large room temperature bore. High magnetic field up to 10 T enabled us to control grain orientation of paramagnetic materials if they have magnetization anisotropy. In the case of cuprate superconductors, the magnetization easy axis is determined by contributions of CuO2 plane and other magnetic elements. To obtain magnetically grain orientated materials, magnetic alignment energy, which is determined by magnitude of magnetic field, volume of grain and magnetization anisotropy, must be larger than the thermal energy, kBT. Recently, we have been focusing on the development of a new and more versatile grain orientation method using cold organic solvent and permanent magnets. Ethanol is chosen as organic solvent, because its melting point is 159 K and very high viscosity at low temperatures. At low temperature, thermal energy decreases monotonically and magnetization anisotropy increases, and therefore, magnetization grain orientation can be possible even under low magnetic field less than 0.5 T. Our preliminary study revealed that c-axis aligned thick films or bulks of Bi2223, Dy123 and Y123 are easily prepared through magnetic grain orientation process under low magnetic fields of 0.14~0.40 T starting from cold or frozen slurry composed of ethanol and oxide powder. Critical current properties and microstructures of these thick films or bulks after heat-treatment will be shown and possibility of the new grain orientation method for the development of various paramagnetic materials having magnetization anisotropy.
