Effect of complex dopants (Li + with Al 3+) substituted for Cu ions in preparing the superconducting YBCO

Abstract

The effect of complex dopants (Li + with Al 3+) substituted for Cu ions was examined in preparing the superconducting YBCO. The same amount of Li + and Al 3+ was simultaneously prescribed to prepare target compounds of the nominal composition YBa 2Cu 3-2 x (LiAl) x O 7-δ. Specimens with dilute concentration of the complex-dopants ( x < 0.1) composed a single phase of the normal YBCO-type crystallite with good superconductivity. Specimens with heavy concentration of the complex-dopants (0.2< x <0.7) were not single phase, but contained crystalline domains of the normal YBCO structure and showed, as a whole, better superconductivity than the specimens of a nominal composition YBa 2Cu 3-2 x O 7-δ without substitutional dopants for all values of x. Therefore, the complex-dopants (Li + with Al 3+) substituted for Cu ions exert interesting effects in preparing the superconducting YBCO.