BaFe4O7 and K0.22Ba0.89Fe4O7: Canted Antiferromagnetic Diferrites with Exceptionally High Magnetic Ordering Temperatures

Ferreira, Timothy; Morrison, Gregory; Chance, W. Michael; Calder, Stuart; Smith, Mark D.; Loye, Hans-Conrad zur

doi:10.1021/acs.chemmater.7b00580

Cited by 19 publications

(35 citation statements)

References 25 publications

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“…The [KO 9 ] polyhedra share rectangular faces with an area of about 12⋅10 4 pm 2 . This structural motif had been reported for BaFe 4 O 7 and K 0.22 Ba 0.89 Fe 4 O 7 as well as for the high pressure phases A 2 Mg 2 Si 2 O 7 ( A =Na, K) ,…”

Section: Resultssupporting

confidence: 75%

“…In the case of strict periodicity this leads to a unit cell with doubled c ‐axis and the space group P 6 3 / mcm (Figure ). Stacking faults or oriented intergrowth of larger domains of the P

\overset{3}{true}

1 m and P 6 3 / mcm polytypes are common and can be understood by order‐disorder (OD) theory . OD theory uses the theory of groupoids to pairs of crystallochemically equivalent layers to describe stacking disorder.…”

Section: Resultsmentioning

confidence: 99%

“…Since this transformation is irreversible, the cooling curve strongly deviates from the heating curve. The chemically and structurally related compounds BaFe 4 O 7 and K 0.22 Ba 0.89 Fe 4 O 7 were also reported to be antiferromagnets with exceptionally high magnetic ordering temperatures ( T N >850 K) …”

Section: Resultsmentioning

confidence: 99%

“…Rietveld refinement on neutron diffraction data of a powder sample of K 2− x Fe 4 O 7− x (OH) x (Figure S3, S4 and Table S4, Supporting Information) confirms the antiferromagnetic order at 300 K and 4 K. The magnetic structure adopts the magnetic space group P

\overset{3}{true}

1 c with lattice parameter c’ doubled with respect to the nuclear structure. All moments are aligned parallel to [001]; no canting of the spins has been found in contrast to the magnetic structures of BaFe 4 O 7 and K 0.22 Ba 0.89 Fe 4 O 7 …”

Section: Resultsmentioning

confidence: 99%

“…35(2) pm, c = 693.04(3) pm). The iron atoms are located in octahedral (Fe1) as well as in tetrahedral oxygen environment (Fe2) with equal multiplicities (Figure 1 [14] as well as for the high pressure phases A 2 Mg 2 Si 2 O 7 (A = Na, K). [15,16] For many K 2À x Fe 4 O 7À x (OH) x crystals we found diffuse scattering contributions or weak additional reflections in the diffraction pattern and conspicuous residuals in the difference Fourier maps (F o À F c ) originating from an alternative stacking of tetrahedra.…”

Section: Crystal Structure Polytypism and Non-stoichiometrymentioning

confidence: 99%

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Oxo‐Hydroxoferrate K_2−xFe₄O_7−x(OH)_x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

et al. 2019

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The reaction of Fe(NO3)3⋅9 H2O with KOH under hydroflux conditions at about 200 °C produces red crystals of K2−xFe4O7−x(OH)x in a quantitative yield. In the crystal structure, edge‐sharing [FeO6] octahedra form ∞2[ Fe2O6] honeycomb nets. Pillars consisting of pairs of vertex‐sharing [FeO4] tetrahedra link the honeycomb layers and form columnar halls in which the potassium ions are located. The trigonal (P true3‾ 1m) and the hexagonal (P63/mcm) polytypes of K2−xFe4O7−x(OH)x show oriented intergrowth. The sub‐stoichiometric potassium content (x≈0.3) is compensated by hydroxide ions. K2−xFe4O7−x(OH)x is an antiferromagnet above 2 K and its magnetic structure was determined by neutron powder diffraction. Under ambient conditions, K2−xFe4O7−x(OH)x hydrolyzes and K2CO3 ⋅ H2O forms gradually on the surface of the K2−xFe4O7−x(OH)x crystals. Upon annealing at air at about 500 °C, the potassium atoms in the columnar halls start to order into a superstructure. The thermal decomposition of K2−xFe4O7−x(OH)x proceeds via a topotactic transformation into K1+x′Fe11O17, adopting the rhombohedral β’’ or the hexagonal β‐aluminate‐type structure, before γ‐Fe2O3 is formed above 950 °C, which then converts into thermodynamically stable α‐Fe2O3.

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Section: Resultssupporting

confidence: 75%

“…In the case of strict periodicity this leads to a unit cell with doubled c ‐axis and the space group P 6 3 / mcm (Figure ). Stacking faults or oriented intergrowth of larger domains of the P

\overset{3}{true}

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

\overset{3}{true}

Section: Resultsmentioning

confidence: 99%

Section: Crystal Structure Polytypism and Non-stoichiometrymentioning

confidence: 99%

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Oxo‐Hydroxoferrate K_2−xFe₄O_7−x(OH)_x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

et al. 2019

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Stuffed Tridymite Structures: Synthesis, Structure, Second Harmonic Generation, Optical, and Multiferroic Properties

Bhim

Sutter

Gopalakrishnan

et al. 2021

Chemistry A European J

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The stuffed tridymite structure Ba(Zn/Co)1−xSi1−xM2xO4 (M=Al3+ and Fe3+) is explored for the possible multiferroic behavior and to develop new inorganic colored materials. The compounds were synthesized by employing conventional solid‐state chemistry methods in the temperature range 1100–1175 °C for 24 h. The powder X‐ray diffraction (PXRD) and Rietveld refinement studies indicate that the compounds stabilize in the P63 space group (no. 173). The refinement results were also rationalized by employing Raman spectroscopic studies. The compounds were found to be second harmonic generation (SHG) active and show weak ferroelectric behavior. The co‐substitution of Co2+ and Fe3+ in the structure gives rise to a weak ferromagnetic behavior to the compound, BaCo0.75Si0.75Fe0.5O4, making it a multiferroic material. The optical studies on the prepared compounds exhibited blue color (Co2+ in Td geometry), purple color (Ni2+ in Td geometry), and simultaneous substitution of Co2+ and Fe3+ gives rise to blue‐green color owing to metal‐to‐metal charge transfer (MMCT) effect.

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Neutron Instruments for Research in Coordination Chemistry

et al. 2019

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Neutron diffraction and spectroscopy offer unique insight into structures and properties of solids and molecular materials. All neutron instruments located at the various neutron sources are distinct, even if their designs are based on similar principles, and thus, they are usually less familiar to the community than commercial X‐ray diffractometers and optical spectrometers. Major neutron instruments in the USA, which are open to scientists around the world, and examples of their use in coordination chemistry research are presented here, along with a list of similar instruments at main neutron facilities in other countries. The reader may easily and quickly find from this minireview an appropriate neutron instrument for research. The instruments include single‐crystal and powder diffractometers to determine structures, inelastic neutron scattering (INS) spectrometers to probe magnetic and vibrational excitations, and quasielastic neutron scattering (QENS) spectrometers to study molecular dynamics such as methyl rotation on ligands. Key and unique features of the diffraction and neutron spectroscopy that are relevant to inorganic chemistry are reviewed.

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BaFe₄O₇ and K_0.22Ba_0.89Fe₄O₇: Canted Antiferromagnetic Diferrites with Exceptionally High Magnetic Ordering Temperatures

Abstract: Crystallographic structure information, magnetic agreement indices, neutron diffraction patterns and magnetic data plots, ICSD and CCDC numbers (PDF) Data for BaFe 4 O 7 (CIF) Data for Ba 0.89 K 0.22 Fe 4 O 7 (CIF)

Cited by 19 publications

References 25 publications

Oxo‐Hydroxoferrate K_2−xFe₄O_7−x(OH)_x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

Oxo‐Hydroxoferrate K_2−xFe₄O_7−x(OH)_x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

Stuffed Tridymite Structures: Synthesis, Structure, Second Harmonic Generation, Optical, and Multiferroic Properties

Neutron Instruments for Research in Coordination Chemistry

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BaFe4O7 and K0.22Ba0.89Fe4O7: Canted Antiferromagnetic Diferrites with Exceptionally High Magnetic Ordering Temperatures

Abstract: Crystallographic structure information, magnetic agreement indices, neutron diffraction patterns and magnetic data plots, ICSD and CCDC numbers (PDF) Data for BaFe 4 O 7 (CIF) Data for Ba 0.89 K 0.22 Fe 4 O 7 (CIF)

Cited by 19 publications

References 25 publications

Oxo‐Hydroxoferrate K2−xFe4O7−x(OH)x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

Oxo‐Hydroxoferrate K2−xFe4O7−x(OH)x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

Stuffed Tridymite Structures: Synthesis, Structure, Second Harmonic Generation, Optical, and Multiferroic Properties

Neutron Instruments for Research in Coordination Chemistry

Contact Info

Product

Resources

About

BaFe₄O₇ and K_0.22Ba_0.89Fe₄O₇: Canted Antiferromagnetic Diferrites with Exceptionally High Magnetic Ordering Temperatures

Oxo‐Hydroxoferrate K_2−xFe₄O_7−x(OH)_x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

Oxo‐Hydroxoferrate K_2−xFe₄O_7−x(OH)_x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures