YBa_2Cu_3O_(6+ε)中超导相和非超导相的结构  

THE STRUCTURES OF YBa_2Cu_3O_(6+ε)SUPERCONDUCTING AND NONSUPERCONDUCTING PHASES

作　　者：陈洗[1] 丁超[1] 王豫[1] 曾宪庭[1] 罗保生[2] 

机构地区：[1]华中理工大学物理系,武汉430074 [2]武汉大学测试中心,武汉430010

出　　处：《低温物理学报》1990年第5期362-366,共5页Low Temperature Physical Letters

摘　　要：采用单晶 X 射线衍射研究了 YBa_2Cu_3O_(6+ε)晶体中正交非超导相和正交高 T_c 超导相的原胞结构.发现非超导相到超导相的转变与 O(1)的占据率大于0.5,相应ε大于0.6有关,并且超导相中 T_c 的提高也与 O(1)的占据率增大到1有关.O(1)的出现,使晶胞参数 b 增长,a、c 缩短,Cu(2)-O(2)-O(3)层畸变增大.我们用原子簇计算的结果说明了结构变化的原因,也用分子轨道从头计算的结果说明了 T_c 的提高.The cell's structures of orthorhombic nonsuperconducting phase and orthorhombic high Tc superconducting phase in YBa2Ca3O6+ε single crystals are studied.It is discovered that the transition from nonsuperconducting phase to superconducting phase is related to whether the occupancy of O(1) is larger than 0.5 and the corresponding ?larger than 0.6.In the superconducting phase,Tc is raised as the occupancy of O(1) is increased to 1.The appearance of O(1) makes the parameter b longer,a and c shorter,and the distortion of Cu(2)-O(2)-O(3) larger.The structure change is explained by the results of atomic cluster calculation,and the increase of Tc can be interpreted by the calculation results with the ab initio MO method.

关 键 词：晶体 超导相 非超导相 结构 

分 类 号：O511.1[理学—低温物理]