零电阻为106.5K的单相超导化合物Bi1.65Pb0.35Sr2Ca2Cu3Oy的制备与超导电性

采用固相反应法合成了名义组份为Bi_2-xPb_xSr₂Ca₂Cu₃O_y (x=0.30;0.35;0.40;0.45)的样品。对样品进行了物相和结构分析,同时测量了电阻-温度关系和直流磁化率。结果表明:x=0.35的样品为单相材料,X射线相分析和电子衍射表明其相结构类似2223相,为四方结构,其晶格常数为a=b=5.414?,c=37.106?,且沿a,b两个方向都观察到调制结构。电阻和直流磁化率测量结果显示:在温度高于50K以上,仅存在一个107K超导相。此外,单相材料的制备条件(组分、烧结温度、室温下淬火及淬火速率)非常苛刻。如同1-2-3相材料一样,氧含量不仅影响样品的成相规律、零电阻温度,而且还严重影响其正常态的输运性质。 关键词：

PREPARATION AND SUPERCONDUCTIVITY OF SINGLE PHASE Bi1.65Pb0.35Sr2Ca2Cu3Oy WITH ZERO RESISTANCE TEMPERATURE 106.5K

Samples with nominal composition Bi_2-xPb_xSr₂Ca₂Cu₃O_y(x = 0.30;0.35;0.40;0.45) have been prepared by solid state reaction. Phase and structure analyses have been performed, and the resistance-temperature relation and dc susceptibility have also been measured. The results show that the sample with x = 0.35 is a single-phase material. X-ray analysis and electron differaction indicate that its phase structure is similar to that of 2223 phase, it is tetragonal with a = b = 5.414?, c = 37.106?, we observed also the modulated structure along a and b. The results of resistance-temperature and dc susceptibility measurement show that, when T = 50 K, there is only one superconducting phase of 107K. In addition, we find that the preparation condition of the single-phase material (composition, sintering temperature and the quenching rate) is stringent. Like the 1-2-3 phase material, the oxygen content not only influences the phase, zero-resistance temperature of the sample, but also influences the transport property of normal state.
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