Bi系超导体高T_c相的形成机制  

THE FORMATION MECHANISM OF HIGH-Tc PHASE IN Bi-BASED SUPERCONDUCTOR

作　　者：裘新良[1] 辛绵荣[1] 罗长勋 李成仁[2] 

机构地区：[1]陕西师范大学物理系,西安710062 [2]西北有色金属研究院,宝鸡721014

出　　处：《物理学报》1992年第4期649-654,共6页Acta Physica Sinica

基　　金：国家超导技术联合研究开发中心资助的课题

摘　　要：本文研究Bi系超导体高Tc(2223)相的形成机制。提出Bi系氧化物超导体高Tc相的形成过程是:首先Sr-Ca-Cu氧化物(Ca_(0.85)Sr_(0.15)CuO_2)与低Tc(2212)相反应形成高Tc相的核,然后样品内2223相核通过象结晶学中晶体生长那样的方式长大成2223相晶粒。2223相成核过程中Sr-Ca-Cu氧化物的形成途径有两条:一条是通过固相反应从Ca_2CuO_3和SrCaCu_5O_8的平衡中形成;另一条是通过液相反应从2212相,Ca_2PbO_4和CuO之间的反应直接形成。固相反应的速度远小于液相反应的速度,从而2223相核的形成速度在液相反应下得到加快。通过高Tc相的形成机制,提出Pb对Bi系超导体高Tc相形成的作用是:它只加速2223相的成核,而对2223相的成长不起作用。最后利用2223相形成机制,烧制出具有织构的样品。In this paper, the formation process of high-Tc phase in Bi-based supercondutor is investigated by X-ray diffraction etc. The high-Tc phase might be formed in the following manner. At first, the nuclei of hig-Tc (2223) phase are formed by the reaction of Sr-Ca-Cu oxide with low-Tc (2212) phase; Then the nuclei of 2223 phase grows, following the manner of ordinary crystal growth. There are two ways to form Sr-Ca-Cu oxide. One is accomplished by solid state reaction between Ca2CuO3 and Ca3(1-x) Sr3xCu5O8, and the other by liquid-state reaction of Ca2PbO4, 2212 phase and CuO. The liquid-state reaction rate is much quicker than that of solid state reaction. So, the rate of formation of 2223 nuclei can be accderated in liquid-state reaction. Based on this mechanism, we propose that Pb can only accelerate the nucleation of 2223 phase and exert no significant influence on the growth of 2223 phase.

关 键 词：铋 超导体 高TC 相 形成 机制 

分 类 号：O511.1[理学—低温物理]