Study of Cu Absorption Edge of YBCO Superconductor by X-Ray Powder Diffraction Method

概要

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Using synchrotron radiation, we carried out X-ray powder diffraction of the YBa_2Cu_3O_y compounds at the several points near the Cu K absorption edge. From the Rietveld analysis of these data, we obtained the anomalous X-ray atomic scattering factor of the Cu ions in the Cu(1) and Cu(2) sites in the superconductor (y=6.90)and the nonsuperconductor (y=6.07). In both compounds, the absorption edge of the Cu ions in the Cu(1) and Cu(2) sites is nearly equal to that of CuO. The results indicate that changes in the O content of YBa_2 Cu_3 O_y produce no significant changes in the valence state of Cu ions in the Cu(1) and Cu(2) sites. Detailed inspection of the spectra, however, shows that the energy position of the edge of the Cu(1) sites in the nonsuperconductor is a little lower than in the superconductor, but the magnitude of the shift is not large as that expected from monovalent Cu ion.
社団法人日本物理学会の論文
1995-09-15