采用溶胶-凝胶方法合成了名义组分为Bi2Sr2-xCaxCuO6+δ(x=0.1、0.3、0.5、0.7和0.9)的系列样品,运用 XRD、TEM和四引线法,研究了钙掺杂对Bi-2201相晶体结构、点阵参数、非公度调制结构和超导临界转变开始温度(T C,onset )的影响。研究发现,钙原子已进入到 Bi-2201单胞内部,在整个掺杂体系内,Bi-2201单胞都能够维持正交点阵；随着钙掺杂量增加,正交单胞的c 轴长度逐渐减小,而当x>0.3时,Bi-2201相调制波矢的b 轴分量逐渐减小,而c 轴分量有所上升；电阻随温度变化曲线表明,当x=0.3时,T C,onset 达到最高,之后有所下降,这与调制波矢在b 轴分量的变化相一致,这种变化能够用晶格失配模型很好地解释。
A series of samples with the nominal composition of Bi2Sr2-xCaxCuO6+δ(x=0.1,0.3,0.5,0.7,0.9) were prepared by sol-gel method.By means of XRD,TEM and standard four-probe technique,it was investiga-ted that the effects of Ca doping on lattice types and parameters of Bi-2201 phase,the incommensurate modula-tion structure and the onset temperature of superconducting critical transition (TC,onset ).It was found that Bi-2201 phase with orthorhombic symmetry can be maintained with the introduction of Ca2+ in the whole doping range.With increasing x,lattice parameter c was decreasing gradually.When x>0.3,the b* component of the modulation wave vector was decreasing while the c* component was increasing with increasing x.Experi-mental R-T curves show that TC,onset was the highest when x=0.3,and then has a declining trend with increas-ing x,which was in agreement with the variation of the b* component of the modulation wave vector and can be interpreted by the crystal misfit model.
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