Fabrication of Y_1-xRE_xBa₂Cu₃O_y films on single crystalline substrates and IBAD buffered metallic tapes by advanced TFA-MOD process

We fabricated Y_1-xSm_xBa₂Cu₃O_y and YSm_xBa₂Cu₃O_y (YSmBCO) films on SrTiO₃ (STO) single crystalline substrates and IBAD buffered metallic tapes (PLD-CeO₂/IBAD-GZO/Hastelloy) by the advanced TFA-MOD process by mixing TFA salts of Y, Sm, Ba and Cu naphthenate, and tried to improve the superconductivity properties compared with those of the pure YBa₂Cu₃O_7-δ (YBCO). As a result, J_c values of Y_1-xSm_xBa₂Cu₃O_y films with x = 0.05 or 0.3, which were fabricated on STO substrates, were improved under the high magnetic fields compared with those of the YBCO without substitution. However, Sm segregation was detected near the STO substrate which was obtained by the TEM-EDS (transmission electron microscopy-energy-dispersive X-ray spectroscopy) analysis. On the other hand, Y_1-xSm_xBa₂Cu₃O_y films with x = 0.05 and YSm_xBa₂Cu₃O_y films with x = 0.3, which were fabricated on IBAD buffered metallic substrates, also improved I_c value under the high magnetic fields compared with those of the YBCO without substitution. Moreover, from the TEM-EDS analysis, Y or Sm segregation was not found. The difference in the Sm segregation behavior between the film on STO and CeO₂ buffered substrates could be explained by the difference in the ratios of the misfit parameters between YBCO/substrate and SmBCO/substrate. Additionally, it was considered that the above phenomenon might be unique in the MOD system and could not be observed in the PLD system, because of the difference in the crystal growth mechanism. In the film of YSm_0.3Ba₂Cu₃O_y, we observed the grains of (Y, Sm)₂O₃ and (Y, Sm)₂Cu₂O₅ by TEM observation. We will further investigate the origin of pinning centers.