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

A structural study of Ruddlesden–Popper phases Sr3−xYx(Fe1.25Ni0.75)O7−δ with x ≤ 0.75 by neutron powder diffraction and EXAFS/XANES spectroscopy

“…For the air-annealed samples, the average position is signicantly higher by 0.63 eV. Albeit the variation of the centroid position for Fe in oxidation states between +3 and +4 is not known to us, this indicates that some Fe 3+ is oxidized upon annealing in air, in contrast to the conclusion in our previous study, 6 where the whole oxygen uptake was attributed to an oxidation of all Ni The half-widths of the Fe pre-edge peaks were found to be $3.2-4.0 eV, i.e., signicantly larger than those in the study of Wilke et al, $1.4 eV. 31 The peak for the air-annealed x ¼ 0.1 is shown in Fig.…”

“…6 Pelletized samples were heated under a N 2 (g) ow at 1300 C for 4 Â 17 h, with intermediate grind-…”

“…In a previous study, we investigated RP n ¼ 2 member phases Sr 3Àx Y x Fe 1.25 Ni 0.75 O 7Àd , 0 # x # 0.75. 6 The ideal stoichiometry of an n ¼ 2 RP phase is A 3 B 2 O 7 , where A is an alkaline-earth or rare-earth element, B is a transition metal element, and the structure contains two ABO 3 perovskite layers that alternate with single AO rock-salt layers, For real n ¼ 2 RP phases, the O1 site may be partially or totally vacant and the O3 site may also be partially vacant, while no evidence for O2 vacancies has been found. [8][9][10][11][12][13] The O content per formula unit, 7 À d, may be as low as 5.45.…”

Magnetic properties of Ruddlesden-Popper phases Sr3−xYx(Fe1.25NiKeshavarz1, Kontos2, Wardecki3 et al. 2018Phys. Rev. MaterialsSelf Cite0000View full textAdd to dashboardCite

“…Such a paramagnetic contribution has also been identified in results from iron-57 Mössbauer spectroscopy studies performed on Sr 3−x Y x (Fe 1. 25 Ni 0.75 )O 7−δ samples [6]. The Mössbauer identified paramagnetic contribution was assigned to paramagnetic Fe 3+ , which due to O3 vacancies can arise from isolated Fe 3+ ions.…”

“…In a previous study, we have investigated the crystal structure and high-temperature properties of the n = 2 RP Sr 3−x Y x (Fe 1. 25 Ni 0.75 )O 7−δ phases (0 ≤ x ≤ 0.75), using X-ray (XRPD) and neutron powder diffraction, thermogravimetry, Mössbauer spectroscopy and electrical conductivity measurements [6]. Samples as-prepared at 1300 • C under N 2 (g) flow as well as samples subsequently air-annealed at 900 • C were studied.…”