掺Mg对Bi Pb Sr Ca Cu O体系中110K超导相生成的影响

用固相反应法合成了名义组分为Bi_xPb_ySr₂Ca_1.7Mg_0.3Cu_zO_w的块状超导体。根据直流电阻和交流磁化率测量的结果,给出了在7个不同温度下烧结的6个组分化合物的超导临界温度。在833℃到843.3℃范围内,110K相对80K相的体积比随着烧结温度的提高而增加。分析了断口形貌。对110K相的生成有影响的Pb和Bi在样品中的剩余量受烧结温度和时间的控制。Bi Pb Sr Ca Mg CuO体系之所以能在较低烧结温度下形成超导相是由于掺Mg造成了部分熔点的降低。

INFLUENCE OF Mg-DOPESG ON GROWTH OF A 110K SUPERCONDUCTING PHASE IN BiPbSrCaCuO SYSTEM

The bulk superconductors with the nominal composition Bi_xPb_ySr₂Ca_1.7Mg_0.3Cu_zO_w(x=1.92, 1.90, 1.87, y = 0.32, 0.315, 0.31, 2 = 3.11, 3.07) are synthesized by solid state reaction. Resistivity and AC susceptibility measurements demonstrate the values of superconducting critical temperature Tc of six kinds of compounds sintered at seven different temperature. The highest zero resistivity temperature Tc(ρ = 0) is 105.8K. x-ray powder diffraction patterns and AC susceptibility measurements show that the volumetric ratio of 110K phase to 80K phase increases with sintering temperature in the range of 833.0℃ to 843.3℃. The break morphology of the sample is studied by SEM. The results of DEAX display that the residual amounts of Pb and Bi in the sample, which have influence on the growth process of 110K phase, are controlled by sintering temperature and time, DTA curves indicate that the lowering of the partial melting temperature caused by the addition of Mg element results in the formation of superconducting phase in Bi Pb Sr Ca Mg Cu O system at lower sintering temperature.