Sol-gel Tb/sub 2/O/sub 3/ buffer layers on ni tapes for YBCO coated conductors

Abstract

In this study, processing of Tb/sub 2/O/sub 3/ buffer layers on textured Ni tapes were evaluated for YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductor. A solution deposition process was used to grow textured Tb/sub 2/O/sub 3/ buffer layers on the Ni tapes. The solution was prepared using Tb-2, 4-pentanedionate precursor, methanol as solvent, chelating agents and a solution modifying chemical, triethanolamine (TEA). Biaxially textured Ni substrates were dipped into the solution by a reel-to-reel sol-gel dip coating system. The amorphous thin films were dried at 300 /spl deg/C for 30 sec and then heat-treated at 500 /spl deg/C for 2 min in air using an in-line three-zone furnace. The films were annealed at temperature range of 900 /spl deg/C and 1170 /spl deg/C for 10 to 20 min under 4%H/sub 2/ - Ar gas flow. The textured buffer layers were obtained using TEA onto the textured Ni tapes at 1150 /spl deg/C for 10 minutes. The Tb/sub 2/O/sub 3/ (222) pole figure revealed a single cube-on-cube texture. The omega and phi scans indicated good out-of-plane and in-plane orientations. DTA results pointed out that Tb based gel film transformed to oxide structure at temperature range of 350 /spl deg/C and 410 /spl deg/C. Microstructures of the Tb/sub 2/O/sub 3/ films were investigated by Environmental Scanning Electron Microscope (ESEM), and the films were dense, smooth and free from cracks and pinholes.