Investigations of chemical interaction between Bi-based 2212 and (RE)Ba 2Cu 3O 7 high Tc superconducting materials

Abstract

Composite materials have been synthesized by mixing 90% (or 95%) YBa 2Cu 3O 7 and 10% (or 5%) Bi 2Sr 2Ca 1Cu 2O 8 by weight, and firing at 900°C to promote grain growth by inducing a liquid phase (Bi 2Sr 2Ca 1Cu 2O 8) in the system. The influence of the amount of liquid phase on the X-ray diffraction data and electrical properties is reported. Energy dispersive X-ray (EDX) analyses are also reported. The YBiBa 2O 6 phase is formed during the heat treatment and introduces additional chemical heterogeneities at the grain boundaries. A previously reported 2212-related superconducting phase, Bi 2(Sr,Ba) 2(Ca,Y)Cu 2O 8+y, could also be formed during the synthesis process, and its effect on the electrical resistance versus temperature measurements is discussed. Attempts to substitute RE ions (Dy 3+, Er 3+, Ho 3+) for Y 3+ in YBiBa 2O 6 have been successful and are reported in an appendix section. X-ray diffraction data are also reported. EDX analyses have been performed specifically for a typical ErBiBa 2O 6 compound and reveal the presence of a new Er 2Ba 4O 7 phase.