T′型214相超伝導体における希土類置換効果 (酸化物超伝導体の材料プロセス化と特性評価<特集>)

概要

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T'-type 214 compounds Ln1.85Ce0.15CuOy with Ln=Pr. Nd, Sm or Eu were prepared. Lattice constants decreased with the substitution in a series from Pr to Eu. The compounds showed superconductivity after reduction. Their lattice constants and oxygen contents did not change so much with the reduction. The reduced Nd compound had a maximum oxygen content of y=3.93 in spite of its highest Tc=24K among the T' compounds. The oxygen contents were 3.79 for Pr, 3.90 for Sm and 3.75 for Eu compounds. Both Cu 2p1/2 and 2p3/2 peaks in XPS were most effectively shifted to lower binding energy in the Nd compound by the reduction process. Their satellite peak intensities were also most strongly reduced in the compound. Cu K-edge XANES spectrum showed 1s-4p*(π) transition for the 3d10 final state most clearly in the reduced Nd compound. These spectrasuggest that electron doping to the conduction plane most effectively occurs in the Nd compound.
社団法人粉体粉末冶金協会の論文