溶胶-凝胶法制备Bi-Pb-Sr-Ca-Cu-O微粉

以金属醋酸盐为原料,用溶胶-凝胶技术制备了Bi-Pb-Sr-Ca-Cu-O微粉,并用TG、DTA、IR、XRD和TEM等手段对Bi_1.85Pb_0.35Sr_1.9Ca₂Cu_3.1O_y粉末的热分解和晶化行为以及粉末粒度进行了分析测试,并用此微粉制备出以2223相为主要物相、零电阻为105K的高温陶瓷超导体。     

LOW-FIELD MICROWAVE SIGNAL IN UNDOPED AND Sb-DOPED Bi-Pb-Sr-Ca-Cu-O

Non-resonant low-field microwave signal in undoped Bi-Pb-Sr-Ca-Cu-O (2223) sample inches monotonously with decreasing temperature, like that in many bulk samples of high-T_c superconductor. But the signed of a Sb-doped sample shows a peak at 103K, and declines gradually and tends to stabilize when the temperature is further reduced. A distorted 2223 phase (i.e., 130K phase) which was an intergrowth of 2223 and insulating monoclinic phases in the Sb-doped sample, was unstable, and it might change into the stable insulating monoclinic phase and lost its superconductivity at lower temperatures.     

高Tc超导体的表面微波吸收

测量不同粒度及低真空条件下高T_c超导样品Bi-Pb-Sb-Sr-Ca-Cu-O的非共振微波吸收信号,实验表明,这个对温度和磁场十分敏感的信号还与样品颗粒的大小及氧气氛有关;并经计算证明,信号强度与近表面趋肤深度壳层Meissner态的体积成正比。 关键词：