CHEMICAL TAILORING OF ELECTRONIC DOPING IN Y_(1-x)Gd_xBa_(1.9)Sr_(0.1)Cu_3O_(7-δ) HIGH T_c SUPERCONDUCTORS

摘要

Solid state thermodynamical reaction method involving mixing, calcinations and sintering were used to prepare high temperature superconductor with a nominal composition Y_(1-x)Gd_x Ba_(1.9)Sr_(0.1)Cu_3O_(7-δ) for Gd (0.1≤ x≤ 0.3). The effect of the substitution of Gd for Y sites and Sr for Ba sites on sintering time, annealing temperature and oxygen content of the superconductor has been investigated to obtain the optimum conditions for the formation and stabilization of the superconducting samples. The critical temperature (Tc) of the samples prepared with different conditions were 120.5 Kand 118 K for x=0.1. While increasing x =0.2 and 0.3 led to decrease Tc to 86.5 K and 81 K respectively, X-ray diffraction analysis showed single phase with orthorhombic structure for all samples.