Physicochemical properties of high-TC (Bi, Pb)-Sr-Ca-Cu-O and Y-Ba-Cu-O superconductors prepared by sol-gel techniquE

Abstract

Abstract High-T c superconducting (Bi, Pb)-Sr-Ca-Cu-O (BPSCCO) and Y-Ba-Cu-O (YBCO) materials were prepared by a liquid-mix technique using ethylene-diamine-tetra-acetic acid (EDTA) as a complexing agent. The decomposition process of the gel precursors was examined by thermogravimetric, differential thermal analysis and differential thermogravimetry (TG, DTA and DTG). The powders of YBCO and BPSCCO oxides obtained by gel decomposition at 530°C contained fine grains with the average diameter 0.5–1.2 μm (BET = 5.7 m 2 /g) and 0.9–1.8 μm (BET = 2.3 m 2 /g), respectively. Physicochemical properties of the obtained powders and bulk samples were characterized by TEM, SEM, XRD, dc electrical resistivity and ac magnetic susceptibility measurements. Sintered samples showed good superconducting properties with T c above 100K for BPSCCO and T c around 90K for YBCO. The obtained fine YBCO powder was also used as a functional material for thick-film paste composition. The paste was screen-printed and dried on ZrO 2 doped with Y 2 O 3 and fired at 960°C peak temperature for 10min. in oxygen. A laser trimming technique was used to provide very narrow superconducting lines for patterned high-T c thick films.