Synthesis and Structural Study of Sr2CuO3+δ Superconductor under High Pressure

A single-phase Sr2CuO3+δ superconductor is synthesized under high temperature and high pressure, in which oxygen atoms only partially occupy the apical sites next to the CuO2 planes and act as hole-dopants. Thesuperconducting transition temperature with Tcmax=75K is achieved in the material. Structure analysis from x-ray powder diffraction data show that this material crystallizes into a K2NiF4 structure with tetragonal unit cell of a=3.795(3)AAand c= 12.507(1)AA. Energy-dispersive synchrotron x-ray-diffraction studies at ambient are performed on powder samples of Sr2CuO3+δ in a diamond-anvil cell at pressure up to 35GPa. Anisotropic compressibility is found. Pressure-induced isostructural phase transition might exist as revealed by the discontinuous change of crystal cell volume V withpressure.