High pressure synthesis of a new superconductor Sr2CuO2+δCl2−y induced by “apical oxygen doping”

Using the apical oxygen doping mechanism, i.e. a partial substitution of divalence O for the monovalence Cl, a p-type oxychloride cuprate superconductor, Sr2CuO2+δCl2−y, was synthesized at high pressure high temperature. The X-ray diffraction refinement suggests the superconductor crystallizes into a 0201 structure with space group I4/mmm and lattice parameters being a = 3.92 Å, c = 15.6 Å. The magnetic susceptibility as well as resistance measurements indicated that the bulk superconductivity with transition temperature (Tc) 30 K was achieved in the sample.