HRTEM study of new series of oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6) |
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Authors: | Anan Y Asaka T Hatano J Zhigadlo N D Takayama-Muromachi E Kimoto K Matsui Y |
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Affiliation: | Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Japan. |
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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. |
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