Out-of-plane effect on the superconductivity of Sr2-xBaxCuO3+delta with T-c up to 98 K

摘要: A series of new Sr2-xBaxCuO3+delta (0 < x 0.6) superconductors were prepared using high-pressure and high-temperature synthesis. Rietveld refinement based on powder x-ray diffraction confirms that the crystallize in K2NiF4-type structure a space group I4/mmm similar to La2CuO4 but with partially occupied apical oxygen sites. It is found superconducting transition temperature T-c this Ba substituted Sr2CuO3+delta superconductor constant carrier-doping level, i.e., delta controlled not only by order/disorder apical-O atoms also content. T-c(max)=98 K achieved material x=0.6 reaches record value among single-layer copper oxide higher than T-c=95 optimally ordered atoms. There Sr-site disorder which might lead reduction T-c. The result indicates another effect surpasses related either increased in-plane Cu-O bond length or elongated distance due substitution larger cation size. present experiment demonstrates optimization local geometry out plane can dramatically enhance cuprate superconductors.