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摘要: 用熔融法制备了Bi2Sr2CaCu2O8+y掺Na多晶样品,转变温度Tc提高到90K以上,最大的零电阻温度达到92.5K。在流动氧气退火后,未掺Na样品Tc显著降低,而掺Na样品Tc几乎不变,说明二者Tc提高具有不同的机制。据此我们认为Na替代了Bi而使Bio层电荷失去平衡,Cuo面上电子转移到Bio层而形成空穴,空穴和电子的吸引相
Abstract: We have prepared Na-doped Bi2Sr2CaCu2O8+y(x=0,0.4,0.5, 0.6, 0.7,0.8,1) samples by melting process. The transition temperature of the samples increased up to 90K, and maximum Tc0 achieved was 92.5K. During annealing in flowing oxygen at-mosphere, the Tc of the undoped sample degrade but in the Na-doped sample there is no dramatic Tc change, that indicates their Tc increase have different mechanism. So we believe Na substitution of Bi may destroy the charge balance of BiO layers, the electrons in CuO planes transfer to BiO layers thus create holes in Cu0 planes, the attraction between holes and electrons may be responsible for the superconductivity.