Recrystallization of YBa2Cu3Ox Superconductors in Vacuum

Abstract

YBa2CU3Ox ceramics were recrystallized in vacuum at high temperatures. Recrystallized layers consisting of small grains were observed near the surfaces of the original large-grain 1 2 3 ceramics. The small grains consisted of transformation twins and were identified to orthorhombic 1 2 3 using X-ray diffraction. As vacuum annealing time increased, the thickness of the recrystallized layer increased. The relationship between the thickness and the annealing time showed a linear relationship and an effective diffusion coefficient of 6.25 x 10(-10) cm2s-1. The recrystallized layer showed a critical temperature of 90 K.