INFLUENCE OF COATING SOLUTION COMPOSITION ON REBa2Cu3Oy (RE=Gd AND Sm, Eu, Gd) FILMS FABRICATED BY FLUORINE-FREE METAL–ORGANIC DEPOSITION

Abstract

GdBa 2 Cu 3 O y ( GdBCO ) and Sm 0.33 Eu 0.33 Gd 0.33 Ba 2 Cu 3 O y ( SEG ) films were prepared by metal–organic deposition (MOD) using two fluorine-free solutions: a metal 2-ethylhexanate (2-EH) and a complex solution (CS) consisting of metal 2-EH and metal-naphthenate. We investigated the effects of these new fluorine-free solutions, and their potential use in the fabrication of several REBCO ( RE : rare earth) materials. The crystal growth, surface morphology, and superconducting properties of films prepared on single-crystal LaAlO 3 substrates at low oxygen partial pressure strongly depended upon the coating solution used. Films prepared using 2-EH exhibited improved thermal stability of the superconducting phase during heat treatment. On the other hand, films prepared by CS had a flat superconducting matrix, with a roughness of several tens of nm and large precipitates 2–3 μm in diameter. In addition, the CS films had a higher critical temperature (91.2 K) than the 2-EH film. The zero-field critical current density at 77.3 K was 0.19 MA/cm2 for 2-EH films, and 0.61 MA/cm2 for CS films.