| 摘要 |
Bulk specimens based on a samarium-barium-copper oxide (Sm-123) high temperature superconductor material are produced by melt-texturing green bodies formed from various starting material powder compositions. Production of melt-textured bulk specimens based on a SmBa2Cu3O7 (Sm-123) high temperature superconductor material, consisting of (by wt.) /-50% Sm-123 and 5-50% Sm2BaCuO5 (Sm-211), 0-45 wt.% Nd4Ba2Cu2O10 (Nd-422) and/or 0-45 wt.% Y2BaCuO5 (Y-211), involves: (A) preparing a starting powder mixture (4 nm to 80 microns particle size) of (a) a matrix forming powder of Sm1.8-1.0Ba2-yCu3-zO7-x (x = 0 to 0.5 exclusive, y= -0.2 to +0.2 exclusive and z = -0.3 to +0.3 exclusive) with additions of (by wt.) 0-20% Sm2O3, 0-50% Sm-211, 0-45% Y-211 and/or 0-45% Nd-422, (b) additions (if not already present) of (by wt.) 0.1-1% PtO2 or Pt and/or 0.1-2% CeO2 or Ce and/or 0.005-1% Rh2O3 or Rh and 0-6% AgO or Ag2O and 0-2% Yb2O3 and (c) <= 17 wt.% total of (by wt.) 0-4% CuO, 0-6% BaCuOx, 0-5% BaO, 0-2% CaO, 0-2% MgO, 0-2% Al2O3, 0-15% BaZrO3 (or BaO + ZrO2), 0-1% ZrO2, 0-1% V2O5, 0-1% TiO2, 0-1% Nb2O5, 0-1% Sb2O3 and/or 0-1% Bi2O3; (B) mixing (with an acceptable carbon uptake of up to 0.18 wt.%), optionally together with an organic binder; (C) forming a green body; and (D) contacting with a seed crystal of decomposition temperature higher than the maximum heat treatment temperature (Tmax) and melt-texturing (under an oxygen partial pressure of /=80 Pa) by heating at 400 K/hr. up to 800 deg C, further heating at 300 K/hr. to 1020-1055 deg C, holding for up to 30 min., rapidly cooling at 500K/hr. to 995 deg C, slowly cooling at 1-2 K/hr. to 960-980 deg C, further cooling at 1-2 K/hr. to 880-885 deg C, further cooling at 600 K/hr. to 800 deg C and further cooling at 300 K/hr. to ambient temperature.
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