Hole Doping Mechanism in Bismuth Cuprates |
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Authors: | Shunji Nomura Hisashi Yoshino Ken Ando |
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Affiliation: | Advanced Research Laboratory, Research and Development Center, Toshiba Corporation, Kawasaki 210, Japan |
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Abstract: | The role of oxygen for the hole doping has been investigated for single-phased (Bi,Pb)2Sr2Ca2Cu3O. z Defects introduced by oxygen have been clarified to be interstitial atoms by pycnometric density measurements. The c axis decreases and the modulation periods along the b axis also decrease with increasing oxygen content in the crystal. It is likely that extra oxygen ions exist between the BiO double layers and those oxygen ions are responsible for the modulation. Samples with oxygen content ranging from 9.99 to 10.18 showed superconductivity. The critical temperature T c , exhibited a maximum value (109 K) at 10.07 oxygen atoms in the formula unit, which coincided with the average Cu valence of 2.13. The data indicated that hole formation was governed by oxygenation reaction in this system. |
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