We have investigated the effects of extra oxygen on the crystal structure, transport properties and superconductivity in the Pb3201 phase of (Pb2Cu)Sr9La1.1CuO6+δ prepared by the polymerized complex method. A structural phase transition from orthorhombic to tetragonal phase is observed with increasing δ. The sample is orthorhombic for 0 ≲ δ ≲ 0.4, tetragonal for 1.7 ≲ δ ≲ 2 and a mixture of the orthorhombic and tetragonal phasse for 0.4 ≲ δ ≲ 1.7. In the orthorhombic phase of δ ≲ 0.3-0.4, Tc increases with increasing δ, owing to the increase of holes in the CuO2 sheets from the extra oxygen. In the tetragonal phase, on the other hand, the superconductivity disappears on account of the small hole concentration in the CuO2 sheets, owing to the increase of the Pb valence from +2 to +4.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering