Specific features of phase equilibriums in Ln–Ba–Fe–O systems
- Volkova, N.E.
- Urusova, A.S.
- Gavrilova, L.Y.
- Bryuzgina, A.V.
- Deryabina, K.M.
- Mychinko, M.Y.
- Lebedev, O.I.
- Raveau, B.
- Cherepanov, V.A.
DOIAbstract
Formation of five-layered Ln 2–ε Ba 3+ε Fe 5 O 15–δ phases [exhibiting nanoscale ordering with layer-by-layer location of the cations in the Ln–Ba–(Ln,Ba)–(Ln,Ba)–Ba–Ln perovskite-type structure] has occurred in the Ln–Ba–Fe–O (Ln = Y, Pr, Nd, Sm, Eu, and Gd) systems at 1100°С in air. Partial substitution of iron with cobalt (Ln 2–ε Ba 3+ε Fe 5–y Co y O 15–δ , Ln = Nd, Sm, Eu) has stabilized formation of the ordered structure. The oxygen content in the complex oxides has been determined in air over a wide temperature range by means of high-temperature thermogravimetry and iodometric titration. The change in oxygen content with temperature for the phases with five-layered ordering was significantly smaller than for the disordered phases. © 2...