YBa 2 Cu 3 O 7−δ (YBCO) films were deposited with a low-fluorine modified trifluoroacetate metalorganic deposition (TFA-MOD) method on SrTiO 3 single crystals and buffered Ni–W metallic tape with a thickness ranging from 450 to 600 nm. The method consists in the substitution of yttrium and copper trifluoroacetates with Cu and Y acetates dispersed in propionic acid. A reduced pyrolysis time with respect to the usual TFA method is obtained. Apart from CuO, no traces of second phases are revealed by x-ray measurements. The films are compact without cracks, and exhibit a slight superficial porosity, but they still remain well connected, and therefore the observed porosity does not affect either the critical current density or the normal state resistivity values, which are indicative of high-quality YBCO films. Moreover, YBCO films were also obtained on Pd-buffered Ni–W, with a CeO 2 /YSZ/CeO 2 buffer layer architecture. These films show good morphological, structural, and superconductive properties with high critical temperature (higher than 91 K) and critical current density higher than 1 MA cm −2 at 77 K in self-field.
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Armenio et al. (2008) studied this question.
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