Non-linear temperature dependence of Hg–O and Cu–O distances in Hg-1212 superconductor

• Published in: Physica. C, Superconductivity Vol. 340; no. 2; pp. 133 - 140
• Main Authors: Yamawaki, Kouji, Sasaki, Satoshi, Kakihana, Masato, Tanaka, Masahiko
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2000
• Subjects: Atomic distance; Hg-1212; Oxide superconductor; X-ray diffraction; 61.10.Nz; X-ray diffraction; Hg-1212; Oxide superconductor; Atomic distance; 74.72.Gr
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/S0921-4534(00)01322-8

The crystal structure of HgBa 2CaCu 2O 6+ δ (Hg-1212) has been carefully examined as a function of temperature by the single-crystal X-ray diffraction method. A significant anisotropy above the T c (=120 K) appeared on out-of-plane interatomic distances, such as Cu–O(2) and Hg–O(2), although the structural environment at room temperature is generally considered to maintain in the temperature vicinity of superconducting transition. On decreasing the temperature, the oxygen atom in the apical O(2) site of CuO 5 pyramid approaches Hg atom and then leaves it. The anisotropic behavior would be precursor with superconductive charge-carriers, where the O(2) site plays the role of a “channel” between Hg charge reservoir and Cu–O superconducting plane.