title: HRTEM study of new series of oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6).
abstract: Arrangements of Cu and anion groups (CO3 and NO3) in the charge-reservoir (CR) blocks of a series of new oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6) were examined by means of electron diffraction and high-resolution transmission electron microscopy (HRTEM). The first three members with n = 1-3 [Tc = 33 K (n = 1), 91 K (n = 2), 90 K (n = 3)] show the 4a0-type superstructures with periodic arrangements, [-Cu-X-X-X-Cu-X-X-X-Cu-] (X = CO3, NO3), in the CR blocks. The third member (n = 3) partly contains the 2a0-type of superstructure with [-Cu-X-Cu-X-Cu] in the CR blocks. The fourth member with n = 4 (Tc = 113 K) contains only the 2a0-type of superstructure. The higher members, with n = 5 (Tc = 65 K) and n = 6 (Tc = 52 K), show no evidence of ordering in the CR blocks, suggesting random arrangements of Cu and anion groups.
authors.affiliation: Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Anan
authors.forename: T
authors.initials: T
authors.lastname: Asaka
authors.forename: J
authors.initials: J
authors.lastname: Hatano
authors.forename: N D
authors.initials: ND
authors.lastname: Zhigadlo
authors.forename: E
authors.initials: E
authors.lastname: Takayama-Muromachi
authors.forename: K
authors.initials: K
authors.lastname: Kimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Matsui