EFFECT OF MIXING 3 RARE-EARTH ELEMENTS ON THE SUPERCONDUCTING PROPERTIES OF REBA2CU3OY

We report the effect of mixing three rare-earth (RE) elements in the R E site on the superconducting properties of melt-processed REBa2Cu3Oy, in which RE elements are selected from the group of Nd, Sm, Eu and Gd . The heat treatment profiles for melt processing were determined acco rding to the peritectic decomposition temperatures obtained from the t hermal analysis measurements. Microstructural observations and composi tional analysis showed that the main phase was (R1(0.33)R2(0.33)R3(0.3 3))Ba2Cu3Oy, in which the ratio of three RE elements (R1, R2, R3) was equal to that of the nominal composition, indicating that mixing of RE elements was uniform. All the samples showed relatively high T-c in t he range 93.1-95.3 K and exhibited the secondary peak effect in the ma gnetization curves at 77 K with the irreversibility field higher than that of melt-processed Y-Ba-Cu-O. A high J(c) value of 50 000 A cm(-2) at 77 K and 2 T was achieved in (Nd, Eu, Gd)Ba2Cu3Oy for field parall el to the c-axis.