SYNTHESIS OF HIGH-TC SUPERCONDUCTORS AT UPPSALA-UNIVERSITY - CERAMICS AND CRYSTAL-GROWTH

Synthetic and process studies of the new high-T(c) super-conductors are carried out using the methods of powder technology. The equipment for these studies at the Institute of Chemistry, University of Uppsala is described. The laboratory is equipped with jaw crusher, various mills, powder mixer, spray dryer and several sintering furnaces. The laboratory has excellent facilities for powder characterization, such as a semi-automatic image analyzer, a system for X-ray line broadening analysis, BET apparatus, sample divider and a sieving machine. Single-crystal growth experiments are also reported. Single crystals of YBa2Cu3O7 and Bi2Sr2CaCu2O8 were grown by the off-stoichiometric method. The largest crystals of YBa2Cu3O7 were obtained with the soaking temperature of 980-degrees-C and a cooling rate of 2-degrees-C h-1. A soaking temperature of 925-degrees-C and a cooling rate of 40-degrees-C h-1 produced the largest Bi2Sr2CaCu2O8 single crystals. A single crystal examination showed that the structure of Bi2Sr2CaCu2O8 is incommensurate along the b axis. The lattice parameters were a = 5.40 angstrom, b = 25.25 angstrom, c = 30.62 angstrom.