Crystal structure and high-temperature properties   of   the Ruddlesden-Popper  phases  Sr3 xYx(Fe1.25Ni0.75)O7-δ (0 ≤ x ≤ 0.75)

Samain, L.; Amshoff, P.; Biendicho, J.J.; Tietz, F.; Mahmoud, A.; Hermann, R.P.; Istomin, S.Y.; Grins, J.; Svensson, G.

Авторы: Samain L., Amshoff P., Biendicho J.J., Tietz F., Mahmoud A., Hermann R.P., Istomin S.Ya, Grins J., Svensson G.
Журнал: Journal of Solid State Chemistry
Том: 227
Год издания: 2015
Издательство: Elsevier B.V.
Местоположение издательства: Netherlands
Первая страница: 45
Последняя страница: 54
DOI: 10.1016/j.jssc.2015.03.018
Аннотация: Ruddlesden-Popper n = 2 member phases Sr3-xYxFe1.25Ni0.75O7-δ, 0 ≤ x ≤ 0.75, have been investigated by X-ray and neutron powder diffraction, thermogravimetry and Mössbauer spectroscopy. Both samples as-prepared at 1300 °C under N2(g) flow and samples subsequently air- annealed at 900 °C were studied. The as-prepared x = 0.75 phase is highly oxygen deficient with δ = 1, the O1 atom site being vacant, and the Fe3+/Ni2+ ions having a square pyramidal coordination. For as-prepared phases with lower x values, the Mössbauer spectral data are in good agreement with the presence of both 5- and 4-coordinated Fe3+ ions, implying in addition a partial occupancy of the O3 atom sites that form the basal plane of the square pyramid. The air-annealed x = 0.75 sample has a δ value of 0.61(1) and the structure has Fe/Ni ions in both square pyramids and octahedra. Mössbauer spectroscopy shows the phase to contain only Fe3+, implying that all Ni is present as Ni3+. Air- annealed phases with lower x values are found to contain both Fe3+ and Fe4+. For both the as- prepared and the air-annealed samples, the Y3+ cations are found to be mainly located in the perovskite block. The high-temperature thermal expansion of as-prepared and air-annealed x = 0.75 phases were investigated by high-temperature X-ray diffraction and dilatometry and the linear thermal expansion coefficient determined to be 14.4 ppm⋅K-1. Electrical conductivity measurements showed that the air-annealed samples have higher conductivity than the as-prepared ones.
Добавил в систему: Истомин Сергей Яковлевич

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Crystal structure and high-temperature properties of the Ruddlesden-Popper phases Sr3 xYx(Fe1.25Ni0.75)O7-δ (0 ≤ x ≤ 0.75)статья

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