The thermal stability and structural modulation were studied systematically in a wide range of 0≤x≤0.4 for the 2201 phase in the Bi-Sr-Cu-O system, Bi2+xSr2-xCuO6+δ, and it was found that these properties varied remarkably at x≈0.1. Compositions 0≤x<0.1 remained stable only in a narrow low-T high-PO(2) region and their modulation period changed stepwisely, not continuously, and reversibly between 4.9b (oxidized) and 5.5b (reduced) when the oxygen content was changed only by 0.65%. In relation to this we propose for 0≤x<0.1 specifically that the change in oxygen content induces the exchange of small amounts of Bi and Sr ions between the `BiO' and `SrO' sheets. The superconductivity of the cation-stoichiometric composition (x = 0) was also studied as a function of oxygen content.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering