Bi系高T_c超导相的研制

A STUDY ON THE PREPARATION OF HIGH T_c SUPER-CONDUCTING PHASE FOR Bi-SYSTEM

在液氨温区的YBaCuO体系超导研究正处于高潮之际,C.Michel等人给出了非稀土的Bi-Sr-Cu-O体系,发现Bi2SrCu2O7+（?）在7—22K出现超导电性转变。之后,H.Maeda等人宣布制备出名义组分为BiSrCaCu2Oy超导体,起始转变温度为105K,而零电阻温度在70K引起了世界各国超导工作者们极大的注意。

A sample of Bi_2 Sr_2Ca_2Cu_2O_y superconductor,its resistance approaches zero at 109K and diamagnetism transition onset temperature is 108K, has been prepared by means of solid state reaction in the mixture of Bi_2O_2, SrCO_3 CaCO_3 and CuO. The mixture was calcined at 800℃ in air for 15h, then powdered and cold-pressed into pellets at a pressure of 4MPa. The pellets were sintersd at 890℃ in air for 14h. By reducing the temperature of the furnace to 400℃, samples were taken out from the furnace.Bi_(2-x)Pb_xSr_2Ca_2Cu_2O_y (x=0.2—0.8) superconductors have been successfully synthesized by solid state reaction. The ceramic samples were sintered at 860℃ in air for 68h.In this paper, the formation of ceramic phase under the above two different sintering conditions are discussed.