We have investigated neutron powder diffraction of YBa2-xSrxCu3O7-d with x=0, 0.4, 0.8 and 1. Their Rietveld analyses were carried out in space group Pmmm assuming two different disordering models: Model A where the O(1) is displaced from (0,1/2,0) to (x,1/2,0) so that each alternate chain has some kind of zig-zag chain and Model B where the available oxygen atoms are located at both the O(1) and O(5) sites to give full and empty Cu-O chains along the a-axis. The refinements based on model B have revealed that substitution of Sr for Ba causes an increase of isotropic temperature factor for the O(1), indicating an increasing in local oxygen disordering. This disordering in the model B is consistent with the Raman results that the defect induced mode gains intensity with increasing Sr content. A .possible picture of the slight decrease of Tc in YBa2-xSrxCu3O7-d is discussed in terms of both local oxygen disordering and associated charge-transfer effect.
|ジャーナル||Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy|
|出版ステータス||Published - 1996 2|
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