EFFECT OF EUTECTIC ADDITIONS AND SINTERING TEMPERATURE ON THE MICROSTRUCTURE, DENSITY AND CRITICAL-CURRENT OF OXALATE DERIVED YBCO

The effects of eutectic (BaCuO2+CuO) additions and sintering temperatu re on the morphology, density and critical current of extruded YBCO wi res, were investigated systematically over a wide range of temperature s (800-975 degrees C) and compositions (0-40 mol%). The YBCO-eutectic system was classified morphologically into five distinct regions, whic h are influenced strongly by the sintering temperature. The main effec t of the eutectic dopant is prevention of the sharp drop of critical c urrent, observed in pure YBCO, at sintering temperatures above 920 deg rees C. This effect is facilitated by suppression of exaggerated aniso tropic grain growth and the development of visible intergranular crack s in material.