Superconductivity in the new compound Sr 2CuO 2(CO 3) 1-x(BO 3) x. The new method for carrier doping on layered copper-oxycarbonates
A new copper oxide superconductor containing carbon and boron Sr 2CuO 2(CO 3) 1- x(BO 3) x was synthesized under ambient pressure. The superconducting transition was observed for the samples with x = 015 and 0.2. The highest Tc(≈32 K) determined by magnetization measurements was obtained for the sample with x = 0.15. The X-ray Rietveld analysis of this compound can be characterized by the tetragonal symmetry (I overline4) with a = 0.77881 (15) nm and c = 1.49681 (3) nm ( x = 0.15). The crystal structure determination suggests that the crystal structure is basically the same as that of Sr 2CuO 2(CO 3).