Nb(Ba)加强Bi系中2223相生成作用研究

固相法合成系列名义组成为Bi_2-xNb_xSr₂Ca₂Cu₃O_y(x=0—1.0)的样品,电学和磁学测量表明,当掺入x=0.2—0.3的Nb有明显加强2223相生成的作用,配比为Bi_1.7Nb_0.3Sr₂Ca₂Cu₃O_y时最佳;当掺Ba以部分取代Sr后有明显协同Nb促进2223相生成的作用,比单掺Nb效果更为显著,其中以Bi_1.7Nb_0.3Sr_1.8Ba_0.2Ca₂Cu₃O_y为最优组成。热重分析(TGA)实验显示,掺Nb(Ba)后样品在～600°C出现吸氧增重;XPS中的O_1s峰显示掺Nb(Ba)后除～531eV的主峰外,在～529eV的肩峰更加明显;讨论了Nb(Ba)对晶体结构的可能影响。 关键词：

A STUDY OF Nb(Ba) ENHANCEMENT 2223 PHASE FORMATION IN Bi-BASED SUPERCONDUCTORS

Properties of a series of superconducting compounds of nominal composition (Bi_2-x,Nb_x)Sr₂Ca₂(Cu_3-yNb_y)O_x(x=0-1.0, y=0-1.0) have been investigated using electrical resistivity, a.c magnetic susceptibility and X-ray powder diffraction measurements. When x =0.2-0.3 or y=0.2, 2223 phase (T_c～110K) in samples is significantly enhanced. The added Nb in the sample with Bi_1.7Nb_0.3Sr₂Ca₂Cu₃O_y has obvious effect of promoting 2223 phase. When furthermore doping Ba as replacing Sr in BiNbSrCaCuO, it is observed that double-doped Nb-Ba has more evident enhancing the high-T_c phase formation than single-doping Nb. The doped Nb-Ba in sample with nominal composition Bi_1.7Nb_0.3Sr_1.8Ba_0.2Ca₂Cu₃O_y is distinctly favour to formation of 2223 phase. From TGA experiment, the weight of sample doping Nb(Ba) at ～600℃ begin to increase by absorbing oxygen. By XPS of O_1s in sample doped with Nb(Ba), the shoulder peak at ～529eV is more evident except for ～531eV as main peak.