Local structure of copper oxide superconductor and superconductivity. Low temperature, precision crystalline structure analysis of Tl2Ba2Ca2Cu3O10(Tl-2223) single crystal

Since the discovery of copper oxide high temperature superconductor, 10 years have elapsed, and in order to elucidate the mechanism of causing superconductivity, the researches have been advanced steadily. In this paper, the noteworthy correlation regarding the change of the local structure around CuO5 pyramid due to temperature, which has become clear by the low temperature, precision crystalline structure analysis using good quality Tl-2223 single crystals, and superconductivity is reported. The circumstance of starting this research is mentioned. The order-disorder change of the oxygen in Tl-O layer occurred near 117 K which is the transition temperature of superconductivity. The change of the local structure around CuO5 pyramid and CuO4 bottom surface and its correlation with superconductivity are reported. The move of the apex oxygen in CuO5 pyramid, to which attention has been paid so far, or the move of the oxygen in CuO4 bottom surface are essentially important, which shortens the interval between the apex oxygen and the oxygen in bottom surface, and makes the CuO4 bottom surface into nearly perfect plane. (K.I.)