SUPERCONDUCTIVITY OF YBA2-XNDXCU3OY SOLID-SOLUTION

The solubility of Nd at the Ba sites and the superconductivity of YBa2 -xNdxCu3Oy were investigated by X-ray powder diffraction and measureme nts of the electrical resistance and ac susceptibility. The single Re1 23 phase was obtained for x less than or equal to 0.30. The onset tran sition temperature T-c(on) is insensitive to the Nd content x in the r egion of x less than or equal to 0.40. All are higher than 95 K. The z ero resistance transition temperatures T-c(zero), however, exhibits tw o-step variation with the increase of x. For x less than or equal to 0 .25, T-c(zero) are all above 92 K. The highest T-c(zero) of 94 K was o btained for x=0.25. For x greater than or equal to 0.3 T-c(zero) drops sharply to about 84 K. Finally T-c(on) falls to 30 K and T-c(zero) is below 10 K for x=0.5. The two-step variation of T-c,might be an indic ation of the existence of two trap levels for holes.