【摘要】 <正> 采用普通固态反应法制备了名义组分为 Bi_1.6Pb_0.4Sr_2-xM_xCa₂Cu₃O_y（M=Mg,Ba）的超导样品,其中 x=0;0.1;0.2;0.4.测量了样品的电阻和交流磁化率与温度的关系.当 Ba 部分替换 Sr 时,x=0.2、0.4的样品在77K 以上仅表现110K 相超导转变.X 射线衍射分析表明,Mg 或者 Ba 部分替换 Sr 虽然促进了2223相形成,但却出现了少量的2201相;而 Mg和 Ba 同时部分替换 Sr 时又抑制了2201相.XRD 及 EDXA 分析表明,Ba²⁺实际替代Sr²⁺的几率要比 Mg²⁺大.更多还原

【Abstract】 The superconducting samples with nominal composition Bi1.6Pb0.4Sr2-xMxCa2Cu3Oy(M = Mg, Ba)were prepared by solid state reaction method. The resistivity and a.c. susceptibility as a function of temperature were measured for the samples. It is found that the samples with x = 0.2, 0.4 only display the superconducting transition of the 110K phase above 77K when M = Ba. XRD indicates that the partial substitution of Mg or Ba for Sr promotes the formation ability of 2223 phase, but the sample contain a small amount of the 2201 phase; the 2201 phase is prevented when Mg and Ba substituted for Sr. XRD and EDXA show that the probability of actual substitution of Ba2+ for Sr2+ is larger than that of Mg+2 for Sr+2.更多还原