Synthesis and structural determination of the new oxide fluoride BaFeO2F

Heap, Richard; Slater, Peter R.; Berry, Frank J.; Helgason, Örn; Wright, Adrian J.

doi:10.1016/j.ssc.2006.11.037

Cited by 55 publications

(65 citation statements)

References 27 publications

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Section: 1mentioning

confidence: 71%

“…The structure of this phase was previously examined by neutron diffraction at 298K and 773K [6] and confirmed cubic symmetry and indicated G-type antiferromagnetic order at the former temperature. However, as noted earlier, the work suggested some displacement of the iron [6]. In an extension of this work, we have now analysed the structure at low temperature (4.2K) to determine if there is a lowering of symmetry and hence a phase transition to a non-centrosymmetric unit cell.…”

Section: 1mentioning

confidence: 71%

“…Hence we now report here on an examination of the structural and magnetic properties of cubic BaFeO 2 F between 4.2 and 650K which modifies the preliminary description of the material [6] and shows it to be substantially different from SrFeO 2 F.…”

Section: Introductionmentioning

confidence: 88%

“…We have recently reported [4,5] on the fluorination of oxygen-deficient perovskiterelated SrFeO 3-δ to give a compound of composition SrFeO 2 F with a cubic unit cell and have formulated a model related to the pattern of substitution by fluorine on the octahedral arrangement of oxygen sites around iron in which SrFeO 2 F undergoes a magnetic transition around 300K from a low temperature state with random spin directions to an antiferromagnetic state. We have also prepared the related cubic phase of composition BaFeO 2 F and, in a preliminary neutron powder diffraction study, found it to exhibit G-type antiferromagnetic order at 298K [6]. However, this preliminary study [6] generated significant questions which required further detailed investigation.…”

Section: Introductionmentioning

confidence: 99%

“…We have also prepared the related cubic phase of composition BaFeO 2 F and, in a preliminary neutron powder diffraction study, found it to exhibit G-type antiferromagnetic order at 298K [6]. However, this preliminary study [6] generated significant questions which required further detailed investigation. For example, the high thermal displacement parameter (3.6Å 2 ) for the iron site suggests the possibility of a series of random displacements.…”

Section: Introductionmentioning

confidence: 99%

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Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

Berry

Coomer

Hancock

et al. 2011

Journal of Solid State Chemistry

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Fluorination of the parent oxide, BaFeO 3-δ, with polyvinylidine fluoride gives rise to a cubic compound with a = 4.0603(4) Å at 298K. 57 Fe Mössbauer spectra confirmed that all the iron is present as Fe 3+. Neutron diffraction data showed complete occupancy of the anion sites indicating a composition BaFeO 2 F, with a large displacement of the Fe offsite. The magnetic ordering temperature was determined as T N = 645±5K. Neutron diffraction data at 4.2K established G-type anti-ferromagnetism with a magnetic moment per Fe 3+ ion of 3.95µ B . However, magnetisation measurements indicated the presence of a weak ferromagnetic moment, which is assigned to the canting of the antiferromagnetic structure. 57 Fe Mössbauer spectra in the temperature range 10 to 300K were fitted with a model of fluoride ion distribution that retains charge neutrality of the unit perovskite cell.

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Section: 1mentioning

confidence: 71%

Section: 1mentioning

confidence: 71%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

Berry

Coomer

Hancock

et al. 2011

Journal of Solid State Chemistry

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Anion Doping: A New Strategy for Developing High‐Performance Perovskite‐Type Cathode Materials of Solid Oxide Fuel Cells

Zhang

Zhu

Zhong

et al. 2017

Advanced Energy Materials

232

126

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energy conversion device allowing the direct conversion of chemical energy to electrical power, and have received considerable attention recently due to their distinguished advantages, such as low greenhouse gases emissions, excellent fuel flexibility, and high energy-conversion efficiency. [5][6][7][8] State-of-the-art SOFCs are composed of yttria-stabilized zirconia (YSZ) electrolyte, a La 0.8 Sr 0.2 MnO 3 (LSM) perovskite cathode, and a nickel-YSZ cermet anode. [9] Because of the pure electronic conducting nature of the LSM cathode and the thick YSZ electrolyte (>100 µm) with relatively low conductivity, such SOFCs should be operated at temperatures higher than 850 °C, introducing several serious barriers for the practical application of SOFCs technology, such as unsatisfactory operational stability due to the facile sintering of electrodes and accelerated interfacial reactions between cell components, as well as high materials and operation cost. [1,10] Many researchers have tried to lower the operation temperatures of SOFCs to the range of 500-800 °C to improve the cell performance, increase chemical compatibility between the cell components, lengthen the cell lifetime, and reduce the cell operation/materials cost. [11][12][13][14][15] However, a simple decrease in operation temperature of state-of-the-art SOFCs to the intermediate-temperature range is always accompanied by an undesired sharp increase in the cell polarization resistance, leading to significant loss in cell power output. [16] Among various losses, the oxygen reduction activity at the cathode has been the most significantly affected and becomes the major obstacle to the practical use of SOFCs at reduced operating temperatures. [17] Consequently, intensive research activities have been performed to develop alternative oxygen reduction electrodes for SOFCs with improved performance at reduced temperatures. [18][19][20] Up to now, many of the attractive cathode materials for intermediate temperature (IT)-SOFCs are composite oxides with perovskite (ABO 3 ) lattice structures, and cation doping is the most adopted strategy for developing new perovskite-type cathode materials. For example, cobalt-based perovskite oxides, such as Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF), [21] Ba 0.9 Co 0.7 Fe 0.2 Mo 0.1 O 3−δ , [22] SrCo 0.8 Nb 0.1 Ta 0.1 O 3−δ , [23] and SrSc 0.175 Nb 0.025 Co 0.8 O 3−δ , [24] exhibit superior electrochemical activity for the oxygen reduction reaction (ORR) at intermediate temperatures. In addition to Overcoming the sluggish activity of cathode materials is critical to realizing the wide-spread application of intermediate-temperature solid oxide fuel cells. Herein, a new way is reported to tune the performance of perovskitetype materials as oxygen reduction electrodes by embedding anions (F − ) in oxygen sites. The obtained perovskite oxyfluorides SrFeO 3−σ−δ F σ and SrFe 0.9 Ti 0.1 O 3−σ−δ F σ (σ = 0.05 and 0.10) show improved electrocatalytic activity compared to their parent oxides, achieving area specific resistance values of 0....

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New Compounds and Structures in the Solid State

Cussen

2007

ChemInform

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Synthesis and structural determination of the new oxide fluoride BaFeO2F

Cited by 55 publications

References 27 publications

Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

Anion Doping: A New Strategy for Developing High‐Performance Perovskite‐Type Cathode Materials of Solid Oxide Fuel Cells

New Compounds and Structures in the Solid State

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