Microdomain formation in the CaFexMn1−xO3−y ferrites

Vallet‐Regí, María; Gonzalez-Calbet, J. M.; Verde, J. C.; Alario-Franco, M.Á.

doi:10.1016/s0022-4596(85)80009-8

Cited by 27 publications

(5 citation statements)

References 18 publications

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“…Such a microstructural feature has already been observed in oxygen-deficient iron double perovskite 18,19 and referred to as a "microdomain texture" 20 schematically represented in Figure 4d. Coming back to the weaker set of spots (0 k/2 l/2), observed in the <100> p ZAP (Figure 4a), these reflections cannot be indexed simply considering a 112-type domain textured sample but could eventually be attributed to multiple scattering of the diffracted beams due to dynamical effects hardly avoidable in electron diffraction.…”

Section: X-ray Diffraction Studymentioning

confidence: 66%

“…The 3D reconstruction of the reciprocal space reveals that the structure of this compound is made up of 112-type ordered domains randomly distributed at a fine scale along the three equivalent ⟨100⟩ p directions of the perovskite subcell, leading to the “average” cubic simple perovskite observed in the XRPD patterns. Such a microstructural feature has already been observed in oxygen-deficient iron double perovskite , and referred to as a “microdomain texture” schematically represented in Figure d. Coming back to the weaker set of spots (0 k /2 l /2), observed in the ⟨100⟩ p ZAP (Figure a), these reflections cannot be indexed simply considering a 112-type domain textured sample but could eventually be attributed to multiple scattering of the diffracted beams due to dynamical effects hardly avoidable in electron diffraction.…”

Section: Electron Microscopy Investigationsmentioning

confidence: 86%

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Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La_0.5Ba_0.5CoO₃: Impact upon Magnetotransport Properties

et al. 2008

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The synthesis and structural study of the stoichiometric perovskite La 0.5 Ba 0.5 CoO 3 have allowed three forms to be isolated. Besides the disordered La 0.5 Ba 0.5 CoO 3 and the perfectly ordered layered LaBaCo 2 O 6 , a third form called nanoscale-ordered LaBaCo 2 O 6 , is obtained. As evidenced by transmission electron microscopy investigations, the latter consists of 112-type 90° oriented domains fitted into each other at a nanometer scale which induce large strains and consequently local atomic scale lattice distortions. These three ferromagnetic perovskites exhibit practically the same T C ≅ 174-179 K, but differently from the other phases, the nanoscale-ordered LaBaCo 2 O 6 is a hard ferromagnet, with H C ≈ 4.2 kOe, due to the strains which may pin domain walls, preventing the reversal of the spins in a magnetic field. The magnetotransport properties of these phases show that all of them exhibit a maximum intrinsic magnetoresistance, close to 6-7 % around T C under ±70 kOe but that the ordered phase exhibits a much higher tunnelling magnetoresistance effect at low temperature of about 15 % against 4 % due to the grain boundary effects.

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Section: X-ray Diffraction Studymentioning

confidence: 66%

Section: Electron Microscopy Investigationsmentioning

confidence: 86%

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La_0.5Ba_0.5CoO₃: Impact upon Magnetotransport Properties

et al. 2008

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“…Observation of a high value for U iso at the O site, see Table , is a common feature for oxygen-deficient perovskites which likely masks a more complex local structure. This was the case for Sr 2 FeMnO 5 , for example, and many other similar materials which have been investigated using more local probes such as electron diffraction , or neutron pair distribution function analysis (NPDF). Here, the latter method is applied to one member of the series, x = 0.5.…”

Section: Resultsmentioning

confidence: 99%

Systematic Study of Compositional and Synthetic Control of Vacancy and Magnetic Ordering in Oxygen-Deficient Perovskites Ca₂Fe_2–xMn_xO_5+yand CaSrFe_2–xMn_xO_5+y (x = 1/2, 2/3, and 1; y = 0–1/2)

Ramezanipour

Greedan²,

Cranswick³

et al. 2012

J. Am. Chem. Soc.

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Ten compounds belonging to the series of oxygen-deficient perovskite oxides Ca(2)Fe(2-x)Mn(x)O(5) and CaSrFe(2-x)Mn(x)O(5+y), where x = 1/2, 2/3, and 1 and y ≈ 0-0.5, were synthesized and investigated with respect to the ordering of oxygen vacancies on both local and long-range length scales and the effect on crystal structure and magnetic properties. For the set with y ≈ 0 the oxygen vacancies always order in the long-range sense to form the brownmillerite structure containing alternating layers of octahedrally and tetrahedrally coordinated cations. However, there is a change in symmetry from Pnma to Icmm upon substitution of Sr for one Ca for all x, indicating local T(d) chain (vacancy) disorder. In the special case of CaSrFeMnO(5) the neutron diffraction peaks broaden, indicating only short-range structural order on a length scale of ~160 Å. This reveals a systematic progression from Ca(2)FeMnO(5) (Pnma, well-ordered tetrahedral chains) to CaSrFeMnO(5) (Icmm, disordered tetrahedral chains, overall short-range order) to Sr(2)FeMnO(5) (Pm3m, destruction of tetrahedral chains in a long-range sense). Systematic changes occur in the magnetic properties as well. While long-range antiferromagnetic order is preserved, the magnetic transition temperature, T(c), decreases for the same x when Sr substitutes for one Ca. A review of the changes in T(c) for the series Ca(2)Fe(2-x)M(x)O(5), taking into account the tetrahedral/octahedral site preferences for the various M(3+) ions, leads to a partial understanding of the origin of magnetic order in these materials in terms of a layered antiferromagnetic model. While in all cases the preferred magnetic moment direction is (010) at low temperatures, there is a cross over for x = 0.5 to (100) with increasing temperature for both the Ca(2)Fe(2-x)Mn(x)O(5) and the CaSrFe(2-x)Mn(x)O(5) series. For the y > 0 phases, while a brownmillerite ordering of oxygen vacancies is preserved for the Ca(2) phases, a disordered Pm3m cubic perovskite structure is always found when Sr is substituted for one Ca. Long-range magnetic order is also lost, giving way to spin glass or cluster-glass-like behavior below ~50 K. For the x = 0.5 phase, neutron pair distribution function (NPDF) studies show a local structure related to brownmillerite ordering of oxygen vacancies. Neutron diffraction data at 3.8 K show a broad magnetic feature, incommensurate with any multiple of the chemical lattice, and with a correlation length (magnetic domain) of 6.7(4) Å.

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“…1a (subindex d refers to the diagonal cell while subindex p refers to the basic cubic perovskite cell). , &(2a unit cell, where in each domain the b-axis is oriented along one of the three different crystallographic directions (11,12). The microdomains appear randomly distributed so that the electron diffraction pattern obtained in Fig.…”

Section: Polymorphmentioning

confidence: 99%

Microstructural Study of the Li+Ion Substituted Perovskites Li0.5−3xNd0.5+xTiO3

García-Martín

Garcı́a-Alvarado

Robertson

et al. 1997

Journal of Solid State Chemistry

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Microdomain formation in the CaFexMn1−xO3−y ferrites

Cited by 27 publications

References 18 publications

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La_0.5Ba_0.5CoO₃: Impact upon Magnetotransport Properties

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La_0.5Ba_0.5CoO₃: Impact upon Magnetotransport Properties

Systematic Study of Compositional and Synthetic Control of Vacancy and Magnetic Ordering in Oxygen-Deficient Perovskites Ca₂Fe_2–xMn_xO_5+yand CaSrFe_2–xMn_xO_5+y (x = 1/2, 2/3, and 1; y = 0–1/2)

Microstructural Study of the Li+Ion Substituted Perovskites Li0.5−3xNd0.5+xTiO3

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Microdomain formation in the CaFexMn1−xO3−y ferrites

Cited by 27 publications

References 18 publications

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La0.5Ba0.5CoO3: Impact upon Magnetotransport Properties

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La0.5Ba0.5CoO3: Impact upon Magnetotransport Properties

Systematic Study of Compositional and Synthetic Control of Vacancy and Magnetic Ordering in Oxygen-Deficient Perovskites Ca2Fe2–xMnxO5+yand CaSrFe2–xMnxO5+y (x = 1/2, 2/3, and 1; y = 0–1/2)

Microstructural Study of the Li+Ion Substituted Perovskites Li0.5−3xNd0.5+xTiO3

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Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La_0.5Ba_0.5CoO₃: Impact upon Magnetotransport Properties

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La_0.5Ba_0.5CoO₃: Impact upon Magnetotransport Properties

Systematic Study of Compositional and Synthetic Control of Vacancy and Magnetic Ordering in Oxygen-Deficient Perovskites Ca₂Fe_2–xMn_xO_5+yand CaSrFe_2–xMn_xO_5+y (x = 1/2, 2/3, and 1; y = 0–1/2)