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- Azad, A. K., et al.
(författare)
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Crystallographic and Magnetic Properties of the Spinel-type Ferrites ZnxCo1-xFe2O4 (0.0
- 2015
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Ingår i: AIP Conference Proceedings. - : AIP Publishing LLC. - 1551-7616 .- 0094-243X. - 9780735413047 ; 1660
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Konferensbidrag (refereegranskat)abstract
- Ultrahigh frequencies (UHF) have applications in signal and power electronics to minimize product sizes, increase production quantity and lower manufacturing cost. In the UHF range of 300 MHz to 3 GHz, ferrimagnetic iron oxides (ferrites) are especially useful because they combine the properties of a magnetic material with that of an electrical insulator. Ferrites have much higher electrical resistivity than metallic ferromagnetic materials, resulting in minimization of the eddy current losses, and total penetration of the electromagnetic (EM) field. Hence ferrites are frequently applied as circuit elements, magnetic storage media like read/write heads, phase shifters and Faraday rotators. The electromagnetic properties of ferrites are affected by operating conditions such as field strength, temperature and frequency. The spinel system ZnxCo1-xFe2O4 (x= 0.0, 0.25, 0.50 and 0.75) has been prepared by the standard solid state sintering method. X-ray and neutron powder diffraction measurements were performed at room temperature. Neutron diffraction data analysis confirms the cubic symmetry corresponding to the space group Fd3m. The distribution of three cations Zn2+, Co2+ and Fe3+ over the spinel lattice and other crystallographic parameters like lattice constant, oxygen position parameter, overall temperature factor and occupancies of different ions in different lattice sites for the samples have been determined from the analysis of neutron diffraction data. The lattice constant increases with increasing Zn content in the system. The magnetic structure was found to be ferrimagnetic for the samples with x
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| 2. |
- Hossain, S., et al.
(författare)
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Highly dense and chemically stable proton conducting electrolyte sintered at 1200 °C
- 2018
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 43:2, s. 894-907
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Tidskriftsartikel (refereegranskat)abstract
- The BaCe 0.7 Zr 0.1 Y 0.2−x Zn x O 3−δ (x = 0.05, 0.10, 0.15, 0.20) has been synthesized by the conventional solid state reaction method for application in protonic solid oxide fuel cell. The phase purity and lattice parameters of the materials have been studied by the room temperature X-ray diffraction (XRD). Scanning electron microscopy (SEM) has been done for check the morphology and grain growth of the samples. The chemical and mechanical stabilities have been done using thermogravimetric analysis (TGA) in pure CO 2 environment and thermomechanical analysis (TMA) in Argon atmosphere. The XRD of the materials show the orthorhombic crystal symmetry with Pbnm space group. The SEM images of the pellets show that the samples sintered at 1200 °C are highly dense. The XRD after TGA in CO 2 and thermal expansion measurements confirm the stability. The particles of the samples are in micrometer ranges and increasing Zn content decreases the size. The conductivity measurements have been done in 5% H 2 with Ar in dry and wet atmospheres. All the materials show high proton conductivity in the intermediate temperature range (400–700 °C). The maximum proton conductivity was found to be 1.0 × 10 −2 S cm −1 at 700 °C in wet atmosphere for x = 0.10. From our study, 10 wt % of Zn seems to be optimum at the B-site of the perovskite structure. All the properties studied here suggest it can be a promising candidate of electrolyte for IT-SOFCs.
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| 3. |
- Zakaria, A.K.M., Asgar, M.A., Ahmed, F.U., Yunus, S.M., Azad, A.K., Paranjpe, S.K., Das, A.
(författare)
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Studies of Mn0.5Cr0.5Fe2O4 ferrite by neutron diffraction at different temperatures in the range 768K ³ T ³ 13K
- 2002
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Ingår i: Indian Journal of Pure & Applied Physics. ; 40, s. 46-53
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Zakaria, A. K. M., et al.
(författare)
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Cation distribution and crystallographic characterization of the spinel oxides MgCrxFe2-xO4 by neutron diffraction
- 2015
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 633, s. 115-119
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Tidskriftsartikel (refereegranskat)abstract
- The spinel system MgCrxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) has been prepared by solid state sintering method in air at 1573 K. X-ray and neutron powder diffraction experiments have been performed on the samples at room temperature for structural characterization. Rietveld refinement of the neutron diffraction data reveals that all the samples of the series possess cubic symmetry corresponding to the space group Fd-3m. The distribution of the three cations Mg, Fe and Cr over the two sublattices and other crystallographic parameters has been determined precisely. The results reveal that Cr has been substituted for Fe selectively. Cr ions invariably occupy the octahedral (B) site for all values of x. Mg and Fe ions are distributed over both A and B sites for all x values. With increasing x the occupation of Mg increases in the A site and decreases in the B site for all the samples, while the Fe ions gradually decreases in both the sites for all values of x. The lattice constant decreases with increasing Cr content in the system. The magnetic structure at room temperature was ferrimagnetic for all the samples.
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| 10. |
- Zakaria, A. K. M., et al.
(författare)
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Study of the magnetic structure in the spinel oxides MnGaxFe1-xCrO4 by neutron diffraction
- 2007
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 310:2, s. E968-E970
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic properties of the spinel system MnGaxFe1-xCrO4 have been investigated using neutron diffraction (ND) technique in the temperature range 600K >= T >= 10 K. The distribution of the magnetic moments in the tetrahedral (A) and octahedral (B) sublattices and their ordering as a function of temperature and composition has been determined. Ferrimagnetic transition temperatures and spin compensation temperatures have been determined for all the specimens. The features observed in the ND results are explained in the light of competing inter and intra-sublattice exchange interactions. A diffuse signal was found to exist below the innermost Bragg reflection with a general increase with increasing compositions indicating the formation of short-range spin clusters.
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