Abstract
Barium lanthanum ferrite and four Mn/Ti substituted materials were synthesized by the sol-gel method. The crystal structure of the materials was studied by a combination of X-ray powder diffraction, electron diffraction, scanning transmission electron microscopy and 57Fe Mössbauer spectrometry. BaLaFe2O6-δ has a cubic perovskite structure and Ba0.7La1.3FeMnO6-δ is distorted perovskite with the R3̅c symmetry, both from electron diffraction and X-ray powder diffraction. However, according to transmission electron microscopy, the crystals of BaLaFeTiO6-δ, BaLaFeTi0.5Mn0.5O6-δ, and BaLaFe0.5Ti0.5MnO6-δ consist of nanodomains with different symmetries (Pm3̅m next to R3̅c due to octahedral tilts), whereas the bulk X-ray powder diffraction patterns for these compounds correspond to the simple cubic structure. 57Fe Mössbauer spectrometry confirms that all materials contain high spin state Fe3+ ions which are strongly influenced by the chemical disorder resulting from various cationic environments.
Mn/Ti substituted materials of BaLaFe2O6-δ with Ba:La =1:1 ratio appear as cubic Pm3̅m from XRD but are determined using TEM to consist of nanodomains of Pm3̅m next to R3̅c, due to octahedral tilts. [Display omitted]
•BaLaFe2O6-δ and four Mn/Ti substituted materials were synthesized.•Nanodomains exist in Mn/Ti substituted materials with La: Ba=1:1 ratio.•Observed domain structure clarifies contradictory structure results in literature.