Synthesis and Structural Study of Sr₂CuO_3+δ Superconductor under High Pressure

A single-phase Sr₂CuO_3+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. The
superconducting transition temperature with T_c^max=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 Sr₂CuO_3+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 with
pressure.