Refinement of the Crystal Structure of Dicalcium Ferrite, Ca2Fe2O5.

Crystal structure analysis of Ca4YFe5O13by combining 1 MeV high-resolution electron microscopy with convergent-beam electron diffraction

“…3 .00 present crystal is determined from the structure model. 0(1) 8(d) 0.25 In order to compare the present crystal structure 0(2) 8(d) 0.00 0(3) 8(d) 0.60 with that of dicalcium ferrite CazFe20 5 which has been 0(4) 8(d) 0.00 determined by Berggren (1971), the structure of 0(5) 8(d) 0.25 Ca2Fe205 is shown in Fig. 5(b).…”

“…Based on this analogy, the dark dots are assigned as Y, Ca and Fe cations. It is then clear that the arrangement of the dark dots can be interpreted intuitively on the basis of the known crystal structure of Ca2Fe205 (Berggren, 1971), in which the structure consists of alternate stacking of Fed 6 octahedra (O layer) and Fed4 tetrahedra (T layer) along groups are non-centrosymmetric Pn2~a or centrosymmetric Pnma. The crystallographic data of Ca4YFe5OIa are summarized in Table 1.…”

Synthesis ofAFeO2.5+x(0≤x≤0.5;A=Sr, Ca) Mixed Oxides from the Oxidative Thermal Decomposition ofA[Fe(CN)5NO]·4H2O

“…Member of the Research Career of the National Scientific and Technological Research Council, Argentina. formed (A Fe O ) with all of the iron in the #3 oxidation state (22,25,26). Brownmillerite-type Ca Fe O , with interstitial O, has been obtained at high O pressures (27,28).…”

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

“…The simplest ordering pattern arises when all oxygen atoms are removed from the perovskite AO layers, leaving the BO 2 layers intact, as in the ''infinite-layer'' AFeO 2 (A¼Ca, Sr) structures [1,2]. Layered ordering of the oxygen vacancies is preserved at higher oxygen content in the A 2 Fe 2 O 5 (A¼Ca, Sr) brownmillerites [3][4][5][6][7][8][9]. They consist of layers of FeO 6 octahedra interleaving with layers of the FeO 4 tetrahedra and demonstrate a variety of polytypes because of the configurational flexibility of the tetrahedral layers [10,11].…”