YBa_2Cu_3O_(7-δ)掺Co样品的中子衍射研究  

NEUTRON POWDER DIFFRACTION STUDIES ON YBa 2Cu 3O 7- δ WITH Co SUBSTITUTION

作　　者：吴小山[1] 陈武鸣[1] 勾成[2] 陈东风[2] 孙凯[2] 

机构地区：[1]南京大学固体微结构物理国家重点实验室南京大学固体物理研究所微结构高等科学技术研究中心 [2]中国原子能科学院

出　　处：《低温物理学报》1998年第2期104-108,共5页Low Temperature Physical Letters

摘　　要：对磁性金属钴掺杂的ＹＢａ２（Ｃｕ１－ｙＣｏｙ）３Ｏ７－δ超导体进行了中子衍射研究．研究表明：钴原子择优占据Ｃｕ（１）晶位；随着钴含量的增加，单胞中平均氧含量增加；晶胞的晶格常数ａ增大，ｂ减小，至ｙ＝０．０３８时，ａ＝ｂ，而ｃ是先增大再减小．在ｙ＝０．０３附近存在一个正交－四方的结构相变，进而讨论了晶胞相变点附近晶体结构形为．Abstract We successfully synthesized YBa 2(Cu 1- y Co y ) 3O 7- δ with y =0.01, 0.03, 0.06 ceramic cuprates. X ray diffraction studies show that there is no impurity phase in all Co doped YBCO. Neutron powder diffraction studies are performed on this Co doped YBCO. Standard Rietveld program are used to refine the neutron powder diffraction data for each sample. The refined results show that Co exclusively occupy Cu(1) site; the oxygen content increases with the increase of cobalt content. YBa 2(Cu 1- y Co y ) 3O 7- δ with y =0.01 has an orthorhombic structure, the space group is Pmmm; sample YBa 2(Cu 0.94 Co 0.06 ) 3O 7- δ has a tetragonal symmetry with the space group of P4/mmm. There are an orthorhombic and a tetragonal phases co existing in sample with y =0.03. The cobalt contents of the tetragonal phase and the orthorhombic phase in YBa 2(Cu 0.97 Co 0.03 ) 3O 7- δ is different. The content of cobalt in the tetragonal phase is 0.038, which is larger than that in the orthorhombic phase (0.028). The lattice parameters a and c increase with y in the orthorhombic phase and b vice versa; On the other hand, in the tetragonal phase, the lattice parameters a=b , and c decrease with the increase of cobalt content. The large lattice with y =0.03 may be related to the lattice distortion, which caused from the phase separation or phase transition.

关 键 词：铬掺杂 中子衍射 YBCO 高TC 超导体 

分 类 号：TM262.014[一般工业技术—材料科学与工程] O511[电气工程—电工理论与新技术]