Magnetic and dielectric behaviors of Ba0.2Sr0.8Co0.8Fe0.2O3-δ oxide

Singh, Sandeep Kumar; Kumar, Jitendra

doi:10.1016/j.jpcs.2006.03.004

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…Heating BSCF in air results in the continuous loss of oxygen at a temperature onset around 673 K [13] and with fixed concentrations of divalent cations at the A site, this process should be accompanied by reduction of the B-site ions, as in β oxygen desorption [24]. Little work on the magnetic properties of BSCF has been done, but for the composition with x = 0.8, y = 0.2, a ferrimagnetic transition was found at 700 K [25], and through refinement of neutron diffraction patterns, the composition with x = 0.5, y = 0.2 showed a G-type antiferromagnetic structure at room temperature with 2.48(1) μ B per B-site ion [11].…”

Section: Introductionmentioning

confidence: 99%

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba_1−xSr_xCo_1−yFe_yO_3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Harvey¹,

Yáng²,

Infortuna³

et al. 2008

J. Phys.: Condens. Matter

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The x-ray absorption spectra of Ba(1-x)Sr(x)Co(1-y)Fe(y)O(3-δ) (BSCF) powders quenched in air from 623 and 1173 K were measured at the oxygen K and transition metal L(II,III) edges. All the samples show a predominantly Fe high spin ground state of 3d(5)L character, while the 3d(6)L Co ions are intermediate spin at 623 K and high spin at 1173 K. Further changes in the metal L(II,III) peaks caused by higher temperature quenching are attributed to changes in symmetry around the cations associated with oxygen loss. The oxygen K spectra show the development of unoccupied states just above the Fermi level for samples quenched from 1173 K. At 1173 K, Ba(1-x)Sr(x)Co(1-y)Fe(y)O(3-δ) shows metallic conductivity, while at 623 K it is a semiconductor; the states developed at high temperature with strong oxygen character are pathways for hole conductivity. Splitting of the transition metal 3d energy levels by the ligand field was observed in the oxygen K spectra, and the range for 10Dq is 1.6-1.8 eV, while the 3d bandwidth is 1.1-1.4 eV in samples quenched from 623 K. On the basis of the soft x-ray absorption results, the classification of Ba(1-x)Sr(x)Co(1-y)Fe(y)O(3-δ) as a material with a negative charge-transfer energy is proposed.

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Section: Introductionmentioning

confidence: 99%

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba_1−xSr_xCo_1−yFe_yO_3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Harvey¹,

Yáng²,

Infortuna³

et al. 2008

J. Phys.: Condens. Matter

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“…Another weight loss took place between 530 and 700 °C was about 21.68 % for BSCF and 23.56 % for BSNCF which can be ascribed to solid state reaction of the carbonate intermediates. In this temperature region, the remaining volatile materials get released . This is also represented by a strong exothermic peak at the DTG curve at about 600 °C.…”

Section: Resultsmentioning

confidence: 92%

“…The second mass loss, of about 29.44 % for BSCF and 25.81 % for BSNCF, was observed on TG‐curves from 185 °C to 530 °C and could be due to the decomposition of the traces of nitrates or citrate that can be desorbed under forms of gaseous molecules such as CO, CO 2 , NH 3 etc. This decomposition could probably correspond to the exothermic phenomena around 400 °C . Another weight loss took place between 530 and 700 °C was about 21.68 % for BSCF and 23.56 % for BSNCF which can be ascribed to solid state reaction of the carbonate intermediates.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Ba_0.5Sr_0.5Ni_xCo_0.8‐xFe_0.2O_3‐δ (x=0 and 0.2) Perovskites as Electro‐catalysts for Methanol Oxidation in Alkaline Media

Fares

Barama

et al. 2017

Electroanalysis

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In this study, the perovskite‐type oxides Ba0.5Sr0.5Ni0.2Co0.6Fe0.2O3‐δ (BSNCF) with different B‐site transition metal elements were investigated as a new catalyst for methanol oxidation. They were prepared by the partial substitution of cobalt by nickel in Ba0.5Sr0.5Co0.8Fe0.2O3‐δ (BSCF) sample. Both materials prepared using a combined citrate/EDTA complexing method and their catalytic activitiesfor methanol oxidation were comparativelystudied using cyclic‐voltammetry (CV) and chronoamperometry (CA) in alkaline media at room temperature. Structural, textural, morphological and redox properties of the synthesized solids were investigated by several physicochemical methods such as XRD, FTIR, LRS, SEM‐EDX, BET and H2‐TPR. The as‐prepared materials were obtained with high purity and high crystallinity. The partial substitution of cobalt by nickel in BSCF perovskite changes the structure of the solid which pass from cubic structure to a mixture of cubic and hexagonal forms. This change is accompanied by an increase in BET surface area and a decrease in crystalline size. For the electro‐catalysis measurements, results demonstrated that partially substituting of Co by Ni in BSCF structure enhance the electro‐catalytical activity towards the oxidation of methanol under alkaline conditions, making it an electro‐catalyst candidate for practical utilization in DMFCs.

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“…Here T c is extracted from the low field magnetization (0.05 T) versus temperature. The magnetization value first decreases slowly with increase of temperature up to a point beyond which the change is [25]. This discrepancy can be understood if there exists antiferromagnetic coupling between the two species themselves and/or with each other.…”

Section: Magnetic Measurementsmentioning

confidence: 99%

On the structural, magnetic and oxygen desorption response of BaxSr1−xFe0.8Co0.2O3−δ (x=0, 0.5 and 1) oxide

Singh¹,

Kumar²

2009

Journal of Alloys and Compounds

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Magnetic and dielectric behaviors of Ba0.2Sr0.8Co0.8Fe0.2O3-δ oxide

Cited by 7 publications

References 15 publications

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba_1−xSr_xCo_1−yFe_yO_3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba_1−xSr_xCo_1−yFe_yO_3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Synthesis and Characterization of Ba_0.5Sr_0.5Ni_xCo_0.8‐xFe_0.2O_3‐δ (x=0 and 0.2) Perovskites as Electro‐catalysts for Methanol Oxidation in Alkaline Media

On the structural, magnetic and oxygen desorption response of BaxSr1−xFe0.8Co0.2O3−δ (x=0, 0.5 and 1) oxide

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Magnetic and dielectric behaviors of Ba0.2Sr0.8Co0.8Fe0.2O3-δ oxide

Cited by 7 publications

References 15 publications

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba1−xSrxCo1−yFeyO3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba1−xSrxCo1−yFeyO3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Synthesis and Characterization of Ba0.5Sr0.5NixCo0.8‐xFe0.2O3‐δ (x=0 and 0.2) Perovskites as Electro‐catalysts for Methanol Oxidation in Alkaline Media

On the structural, magnetic and oxygen desorption response of BaxSr1−xFe0.8Co0.2O3−δ (x=0, 0.5 and 1) oxide

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Development of electron holes across the temperature-induced semiconductor–metal transition in Ba_1−xSr_xCo_1−yFe_yO_3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Development of electron holes across the temperature-induced semiconductor–metal transition in Ba_1−xSr_xCo_1−yFe_yO_3−δ(x,y= 0.2–0.8): a soft x-ray absorption spectroscopy study

Synthesis and Characterization of Ba_0.5Sr_0.5Ni_xCo_0.8‐xFe_0.2O_3‐δ (x=0 and 0.2) Perovskites as Electro‐catalysts for Methanol Oxidation in Alkaline Media