Crystal growth and superconductivity of Y1−xNdxBa2Cu3O7−δ solid solutions

Abstract

Abstract Single crystals of Y1−xNdxBa2Cu3O7−δ [Y(Nd)BCO] solid solutions, in which the Nd content x ranged from 0.098 to 0.410, were grown by the crystal pulling method. The Nd substitution content x in the crystal can be controlled with the processing temperature. With an increase of the processing temperature, the Nd concentration in the liquid increased, and accordingly, resulted in the higher Nd substitution content in single crystals. When x=0.410, the ratio of Nd+Y to Ba in single crystals became high and the Tc was depressed, indicating evidence of the Nd substitution at Ba sites. The critical temperature Tc of 89±2 K was obtained from oxygenated Y1−xNdx Ba2Cu3O7−δ single crystals at 340°C for 200 h and could be enhanced up to 91 K by annealing at 500°C for 3 days. For all Y(Nd)BCO solid solutions, even a small amount of Nd content (x=0.098), the second peaks appear in the range of 1.2–1.7 T for the applied field H parallel to the c-axis of samples in the M–H loops, which may be due to a double substitution of both Y3+ and Ba2+ by Nd3+. X-ray measurements of the lattice parameter proved the above double substitution.