Superconducting Sr2−xAxCuO2F2+δ(A=Ca, Ba): Synthetic Pathways and Associated Structural Rearrangements
✍ Scribed by M.G. Francesconi; P.R. Slater; J.P. Hodges; C. Greaves; P.P. Edwards; M. Al-Mamouri; M. Slaski
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 391 KB
- Volume
- 135
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The low-temperature fluorination of a range of insulating alkaline earth cuprates Sr 2 -x A x CuO 3 (A ؍ Ca (04x42); A ؍ Ba (04x40.6)) can result in superconducting oxide fluorides Sr 2 -x A x CuO 2 F 2; . In contrast, conventional high-temperature solid-state reactions produce thermodynamically more stable mixtures of oxides and fluorides. Various soft-chemistry fluorination pathways (utilizing F 2 gas, NH 4 F, MF 2 [M ؍ Cu, Zn, Ni, Ag]) are compared with respect to their efficacy and mechanisms. Attention is also focused on the structural features of the mixed-oxide precursor and the final-oxide fluorides to highlight the remarkable structural rearrangements that occur during the low-temperature fluorination. The effects of fluorination of other Sr-Cu-O systems are used to identify the structural requirements of the precursor oxide in order to achieve such transformations.