A comparative study of superconducting LaBa 2Cu 3O 7-δ and La 3- xBa 3+ xCu 6O 14+δ
Abstract
Based on X-ray diffraction and electron microscopy it is shown that oxides of the general formula La Ba 2Cu 3O 7-δ become tetragonal when δ deviates slightly from 0. This tetragonal structure is similar to that of La 3- xBa 3+ xCu 6O 14+δ, with a cubic perovskite subcell and triple periodicity. Electron micrographs of these tetragonal oxides show 90° microdomains. Orthorhombic LaBa 2Cu 3O 7-δ with high Tc (∼77 K) is found only when δ ⋍ 0; this sample is subject to formation of twins. Fluorine substitution seems to favor superconductivity.
- Publication:
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Journal of Solid State Chemistry France
- Pub Date:
- April 1988
- DOI:
- 10.1016/0022-4596(88)90154-5
- Bibcode:
- 1988JSSCh..73..593G