THE DIMPLING IN THE CuO2 PLANES OF YBa2Cu3Ox (x=6.806–6.984, T=20–300K) MEASURED BY YTTRIUM EXAFS

Abstract

The dimpling of the CuO 2 planes (spacing between the O2,3 and Cu2 layers) in YBa 2 Cu 3 O x has been measured as a function of oxygen concentration and temperature by yttrium x-ray extended-fine-structure spectroscopy (EXAFS). The relative variations of the dimpling with doping (x = 6.806 − 6.984) and temperature (20-300 K) are weak (within 0.05Å), and arise mainly from displacements of the Cu2 atoms off the O2,3 plane towards Ba. The dimpling appears to be connected with the transition from the underdoped to the overdoped regimes at x = 6.95, and with a characteristic temperature in the normal state, T * ≃ 150 K.

The normal-state anomalous behaviours studied by internal friction of partially Sr-substituted Y123 in the underdoped range

“…For the sample with high oxygen content, there is a broad peak around 150 K. It is depressed with decreasing the oxygen content. We suspect that it might relate to the microstructure change, where a minimum of CuO 2 plane dimpling was observed [32].…”