Coupled anion and cation ordering in Sr3RFe4O10.5 (R=Y, Ho, Dy) anion-deficientperovskites

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)

“…(Naturally, these contrast variations give rise to the same satellite reflections in the FFT of the HREM image as in the n Values are given for bank 6 at 154.4o. [15] Upon longer exposure to the electron beam the modulation along /1 0 0S p in the /1 1 0S p pattern disappears and instead an ordering along /1 1 1S p appears in the in thicker parts of the crystallites, as indicated in the image. This ordering is better seen in the corresponding FFT image, insets (a) and (b) in Fig.…”

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

“…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 . 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 []).…”

Successive and Site-Selective Oxygen Release from B-Site-Layer-Ordered Double Perovskite Ca2FeMnO6 with Unusually High Valence Fe4+

“…According to the × × 4 c p unit cell, the observed 0 k 0 ( k = 2 n ), 00 l ( l = 2 n ), and h 0 l ( h + l = 2 n ) reflection conditions correspond to the extinction groups P 4 2 / mnm and Pmnm , which allows the space group P 4 2 / mnm . This space group is also found in the A-site-ordered oxygen-deficient perovskites Sr 3 R Fe 3+ 4 O 10.5 ( R = Y, Ho, Dy), where oxygen vacancies indeed are introduced in every other Fe layer along the layered direction (the FeO 6 and FeO 4.5 polyhedral layers stack alternately), and the oxygen vacancies were suggested to be ordered within the × oxygen-deficient Fe layers, which produces a regular arrangement of FeO 5 and FeO 4 polyhedra . In Ca 2 FeMnO 5.5 , based on the space group, a systematic arrangement of the FeO 5 polyhedra due to the oxygen-vacancy ordering within the Fe layers is most likely.…”