Structural and magnetic properties of the perovskites A2LaFe2SbO9 (A = Ca, Sr, Ba)

Polycrystalline samples of A2LaFe2SbO9 (A ​= ​Ca, Sr, Ba) perovskites appeared monophasic to X-ray or neutron powder diffraction but a single-crystal study utilising transmission electron microscopy revealed a greater level of complexity. Although local charge balance is maintained, compositional an...

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Bibliographic Details
Published in:Journal of solid state chemistry 2021-03, Vol.295, p.121914, Article 121914
Main Authors: Hendrickx, Mylène, Tang, Yawei, Hunter, Emily C., Battle, Peter D., Hadermann, Joke
Format: Article
Language:English
Subjects:
Compositional inhomogeneity
Crystal structure
Magnetic properties
Perovskite oxides
Structural variations
Transmission electron microscopy
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Summary:Polycrystalline samples of A2LaFe2SbO9 (A ​= ​Ca, Sr, Ba) perovskites appeared monophasic to X-ray or neutron powder diffraction but a single-crystal study utilising transmission electron microscopy revealed a greater level of complexity. Although local charge balance is maintained, compositional and structural variations are present among and within the submicron-sized crystals. Despite the inhomogeneity, A ​= ​Ca is monophasic with a partially-ordered distribution of Fe3+ and Sb5+ cations across two crystallographically-distinct octahedral sites, i.e. Ca2La(Fe1.25Sb0.25)2d (Fe0.75Sb0.75)2cO9. For A ​= ​Sr or Ba, the inhomogeneities result in differences in the tilting patterns of the octahedra and the ordering of the B cations. Particles of A ​= ​Sr contain a phase (Fe:Sb ~2:1) without B cation ordering and one (Fe:Sb ~1:1) with B cation ordering. Monophasic A ​= ​Ba lacks long-range cation order although ordered nanodomains are present within the disordered phase. The temperature dependence of the magnetic properties of each sample is discussed. [Display omitted] •Increasing size of the substituted A cation decreases the octahedral tilts•TEM revealed local variations in the composition that maintained the charge balance•Ordered and disordered domains coexist in Ba2LaFe2SbO9 and Sr2LaFe2SbO9•Ca2LaFe2SbO9 is ferrimagnetic, whereas Ba2LaFe2SbO9 is antiferromagnetic
ISSN:0022-4596
1095-726X
DOI:10.1016/j.jssc.2020.121914