Order-disorder transition of Sr2Fe2O5 from brownmillerite to perovskite structure at an elevated temperature

Structural Phase Transitions in Sr2Fe2O5 under High Pressure

“…There is, however, disagreement about the detailed transition temperatures and phases. Shin et al (11) reported a change from a brownmillerite to a cubic perovskite (P) phase for Sr Fe O near 973 K. Two crystallographic phase transitions near 623 and 1123 K were established by Grenier et al (12). The "rst transition leads to a mixture of the B-type and a tetragonal perovskite (Q) phase, the second transition revealed a hysteresis, and a cubic perovskite phase was observed above 1123 K. On the other hand, in the study by Takeda et al (13) (16).…”

Crystal and Magnetic Structures of Sr2Fe2O5 at Elevated Temperature

“…Moreover, it is impossible to accommodate a nine-atom molecule in the cell and still get the perovskite structure. The wrong choice was biased by the fact that the fully oxidized SrFeO phase forms such a structure and has similar lattice constant (10). High calculated density indicates that the perovskite cell, obtained by direct indexing of the patterns, is too small to describe the compound.…”

“…Previously this phase was thought to have the cubic perovskite structure with disordered oxygen sites (10,11 (10,20). However, if we assume that the cell contains only one chemical formula (molecule) of the oxide, this choice of unit cell gives unreasonably high density "9.65 g/cm .…”

“…Published variations of lattice constants with temperature di!er among the authors. Shin et al (10) reported an increase of all three lattice constants up to the NeH el point, then a decrease of one of them and continuous transformation to the cubic form. On the other hand, Takeda et al (11) communicated a steady increase of all lattice parameters with temperature and the transition to the cubic structure with a substantial change in the unit cell volume.…”

The role of fuel-borne catalyst in diesel particulate oxidation behavior

“…For FBC-doped soot at 75% load, all peaks in Fig. 5a can be identified as a mixture of amorphous carbon around 25 • of 2θ and strontium iron oxide (SrFeO 2.5 ) that gave rise to three intensive peaks around 32 • , 46 • , and 57 • of 2θ [36]. Another possible assignment of these peaks is Fe 2 O 3 (hematite), which can generate similar reflection peaks in these 2θ regions [37,38].…”