Synthesis and characterization of perovskite-type SrxY1−xFeO3−δ (0.63≤x<1.0) and Sr0.75Y0.25Fe1−yMyO3−δ (M=Cr, Mn, Ni), (y=0.2, 0.33, 0.5)

Abstract

Synthesis and characterisation of perovskite SrxY1-xFeO3-d (=.63≤x<1) and Sr0.75Y0.25Fe1-yMyO3-d (M=Cr, Mn, Ni) (y= 0.2, 0.33, 0.5). Chemistry, http://dx.doi.org/10. 1016/j.jssc.2013.01.008 Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Journal of Solid State

Phase equilibria, structure, oxygen nonstoichiometry, and thermal expansion of oxides in the 1/2Y2O3–SrO–1/2Fe2O3 system

“…Figure demonstrates the ideal perovskite cubic cell without any additional reflections. In general, this agrees with the findings made by Biendicho et al, who observed only partial local ordering in the HREM images of Sr 0.75 Y 0.25 FeO 3−δ , due to small variations in the oxygen content that caused a formation of local structural units.…”

“…Battle et al reported on Sr 2 YFe 3 O 8+ y prepared at 1573 K in air by a standard solid‐state method . The samples of the general composition Sr x Y 1− x FeO 3−δ with x = 0, 0.25, 0.5, 0.75, 1 and 0.63 ≤ x < 1 were synthesized in air at 1473 and 1573 K, respectively. The synthesis was performed inside silica tubes sealed under vacuum (10 −2 mbar) with subsequent firing at 1100–1150°C; this allowed to prepare the ordered phase Sr 3 YCo 4 O 10.5+δ .…”

“…The synthesis was performed inside silica tubes sealed under vacuum (10 −2 mbar) with subsequent firing at 1100–1150°C; this allowed to prepare the ordered phase Sr 3 YCo 4 O 10.5+δ . Summarizing the aforementioned data, one can conclude that the phase equilibria in the Y 2 O 3 –SrO–Fe 2 O 3 system are unclear, and the available information about the homogeneity range in a Sr x Y 1− x FeO 3−δ solid solution is contradictory (the values of x = 0.25 and 0.5 obtained in [] lie outside of the range 0.71 ≤ x ≤ 0.91 reported in []). Therefore, the aims of present work are: (a) the determination of homogeneity ranges and the crystal structure of the solid solutions formed in the 1/2Y 2 O 3 –SrO–1/2Fe 2 O 3 system; (b) the characterization of oxygen content in the obtained solid solutions and determination of its changes with temperature; (c) the determination of thermal expansion for the obtained solid solutions; (d) establishing the phase equilibria in the 1/2Y 2 O 3 –SrO–1/2Fe 2 O 3 system and a comparison of the obtained phase diagram with the related 1/2Ln 2 O 3 –SrO–1/2Fe 2 O 3 (Ln = Nd, La) and 1/2Y 2 O 3 –MO–1/2Fe 2 O 3 (M = Ca, Ba) systems.…”

Crystal Structure and Coordination of B-Cations in the Ruddlesden–Popper Phases Sr3−xPrx(Fe1.25Ni0.75)O7−δ (0 ≤ x ≤ 0.4)

“…At higher temperatures, the conductivity starts to decrease due to oxygen loss and associated decrease of charge carrier concentration due to a reduction of the average oxidation state of the B-cations. This is similar to what reported in related systems-Sr 3 FeNiO 7−δ [10], Sr 3 Fe 2 O 7−δ [10], and Sr x Y 1−x FeO 3−δ [28] and Sr 3−x Y x Fe 1.25 Ni 0.75 O 7−δ [14]. It should also be noted that conductivity for the Pr-containing sample is an order-of-magnitude higher than that reported for the Y-system.…”

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

“…25 Ni 0.75 O 7 À δ [19]. The substitution of Sr by Y in Sr 3 (Ni,Fe) 2 O 7 À δ RP phases could possibly decrease the thermal expansion due to the higher strength of the Y-O bond as compared to the Sr-O bond [20].…”