A point defect modeling study of the oxygen nonstoichiometry and high‐temperature electrical properties of La2−xAExCuO4−y (AE = Ba, Sr, and Ca) systems indicates that, whereas oxygen excess (y < 0) due to oxygen interstitials predominates as x→ 0, oxygen deficit (y > 0) results primarily from dopant‐vacancy associates at large x; isolated oxygen vacancies are apparently minority defect species. The onset of oxygen deficiency due to dopant‐vacancy associates occurs at x∼ 0.15 in the AE = Ba and Sr systems but at x∼ 0.05 in the AE = Ca system. Ideal ionic point defect behavior persists to x∼ 0.4 in the AE = Ba and Ca systems and to x∼ 0.5 in the AE = Sr system. A premature flattening of the electrical properties above x∼ 0.2 occurs in the AE = Ba and Sr systems. Reasons for the extensive range of ideal ionic behavior and for the onset of degenerate electronic behavior are discussed, as are ramifications for high‐Tc superconductivity in these materials.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of the American Ceramic Society|
|State||Published - Jan 1994|
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry