STRUCTURE AND PROPERTY OF YBA2CU3OX TAPES FORMED ON METALLIC SUBSTRATE BY CVD TECHNIQUE

YBCO superconducting tapes with good superconducting property were pre pared by a continuous CVD technique on 300mm long Hastelloy with biaxi ally aligned YSZ buffer layer. High Jc of larger than 5x10(8)A/m(2) (7 7K, 0T) covering the full length of the tapes that included the maximu m value of 5.9x10(9)A/m(2) (Ic=10.4A) were achieved. The structure of YBCO tapes with high Je larger than 10(9)A/m(2) have been studied usin g by scanning electron microscopy (SEM), energy dispersive X-ray spect roscopy (EDS) and transmission electron microscopy (TEM). The precipit ates with a size of 1-3 mu m were observed in the SEM and TEM images o f YBCO tapes, and these were characterized as the gathering of Cu-O an d Y-Ba-Cu-O grains with a size of 0.1-0.5 mu m by the EDS analysis. An area of these second phase was estimated at 10-20%, but these grew fr om a part of 0.3 mu m in the thickness from the bottom of YBCO layer, so the effective volume of the current path within these region were n ot completely blocked. Good c-axis oriented growth of YBCO layer norma l to the flat surface of YSZ buffer layer was shown in the cross-secti onal TEM view, in addition the intermediate layer as barium zirconate (BZO) with 15-20nm in the thickness was formed on the top of YSZ layer .