Structural and electrical behavior evaluation of Ho-substituted Co2W hexagonal ferrites

Aen, Faiza; Wasiq, M.F.; Rana, M.U.; Khan, Hasan M.; Khan, Muhammad Azhar

doi:10.1016/j.ceramint.2016.07.118

Cited by 25 publications

(6 citation statements)

References 25 publications

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“…The electrical resitivity ( ρ ) is substantially decreased by Sm‐CrAl substitution from 574.6 × 10 7 Ω‐Cm at x=0.00, y=0.00 to 0.213×10 7 Ω‐Cm at x=0.40, y=0.32, corresponding to a decrease of more than three orders of magnitude. In the case of ionic solids, such as spinel and hexaferrite, the conductivity mechanism is attributed to the hopping of electrons between Fe 3+ and Fe 2+ ions at the octahedral sites [56–58] . For the hexaferrites Ba 0.20 Sr 0.80‐x Sm x Fe 12‐y (Cr 0.5 Al 0.5 ) y O 19 , the substitution of Fe 3+ ions by Cr 3+ and Al 3+ ions does not lead to a valence change, while in order to maintain the electrical neutrality because of the substitution of Sr 2+ ions by Sm 3+ ions, some Fe 3+ ions convert into Fe 2+ ions [59] .…”

Section: Resultsmentioning

confidence: 99%

“…In the case of ionic solids, such as spinel and hexaferrite, the conductivity mechanism is attributed to the hopping of electrons between Fe 3 + and Fe 2 + ions at the octahedral sites. [56][57][58] For the hexaferrites Ba 0.20 Sr 0.80-x Sm x Fe 12-y-(Cr 0.5 Al 0.5 ) y O 19 , the substitution of Fe 3 + ions by Cr 3 + and Al 3 + ions does not lead to a valence change, while in order to maintain the electrical neutrality because of the substitution of Sr 2 + ions by Sm 3 + ions, some Fe 3 + ions convert into Fe 2 + ions. [59] The increasing number of Fe 2 + ions results in the increase of the hopping probability between the Fe 3 + and Fe 2 + ions.…”

Section: Magnetic Measurementsmentioning

confidence: 99%

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Synthesis, Magnetic and Electrical Characteristics of Ba‐Sr Hexaferrites Substituted with Samarium, Chromium and Aluminum

et al. 2021

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A series of M‐type Ba−Sr hexaferrites of composition Ba0.20Sr0.80‐xSmxFe12‐y(Cr0.5Al0.5)yO19 (x=0.00–0.40; y=0.00–0.32) were prepared by solid‐state reaction route. XRD patterns reveals that there is a single magnetoplumbite phase in the hexaferrites with the substitutiom of Sm (0.00≤x≤0.20) and CrAl (0.00≤y≤0.16) contents, while for the hexaferrites containing Sm (x≥0.30) and CrAl (y≥0.24), impurity phase is detected in the structure. The remanence (Br) decreases with increasing substitution content of Sm (0.00≤x≤0.40) and CrAl (0.00≤y≤0.32). With the increase of substitution contents, the intrinsic coercivity (Hcj) increases, while the magnetic induction coercivity (Hcb) first increases, and then decreases. Br has a linear decreasing behavior with increasing temperature from 20 °C to 170 °C. Hcj raises linearly with increasing temperature from 20 °C to 170 °C. The average temperature coefficient of Br (αBr) basically remains constant with increasing substitution content of Sm (0.00≤x≤0.40) and CrAl (0.00≤y≤0.32). The average temperature coefficient of Hcj (αHcj) decreases with increasing substitution content of Sm (0.00≤x≤0.40) and CrAl (0.00≤y≤0.32). The electrical resitivity (ρ) decreases with increasing substitution content of Sm‐CrAl.

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Section: Resultsmentioning

confidence: 99%

Section: Magnetic Measurementsmentioning

confidence: 99%

Synthesis, Magnetic and Electrical Characteristics of Ba‐Sr Hexaferrites Substituted with Samarium, Chromium and Aluminum

et al. 2021

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“…[60] They were discovered and characterized in the early 1950s, and their practical value has sparked an exponential increase in attention since then. [61][62][63][64][65][66][67][68][69] They are among the most researched materials in high-frequency devices. [69][70][71][72] They are ideal for applications such as radar absorption materials due to their high permeability, [73] high saturation magnetization, high coercivity, [74,75] strong chemical stability, good resistivity, and low eddy current losses.…”

Section: Hexagonal Ferritesmentioning

confidence: 99%

“…[101] Divalent ions can be substituted to modify magnetic characteristics, [102] and electromagnetic properties can be affected by rare earth element replacement due to its typical relaxation characteristics. [66,103] Qin et al [104] formed MnZn-doped W-type and MW absorption in the 2-18 GHz region. From the result, the reflection loss peak for sample with a thickness of 2.8 mm was 40.7 dB at 7.3 GHz, with 6.6 GHz bandwidth and loss of less than 10 dB.…”

Section: W-type Hexaferritementioning

confidence: 99%

Recent Progress in Hexagonal Ferrites Based Composites for Microwave Absorption

Mohammed

Mohammed²,

Srivastava

2022

Cryst. Res. Technol.

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With the fast growth of wireless communication technology in high‐frequency ranges, electromagnetic (EM) interference has become a growing concern that has drawn international attention. The development of materials that can absorb EM radiation is a crucial solution. This review provides a detailed overview of ferrites, specifically hexagonal ferrites and their composites for microwave (MW) absorption. It examines hexagonal ferrite classifications based on the stacking order of their fundamental blocks and their synthesis methods and strategies for improving their magnetic properties. On the other hand, this review included a detailed examination of hexagonal ferrites–conducting polymer, hexagonal ferrites–2D materials, and hexagonal ferrite–other nanomaterials composites for MW absorption applications. Enhancing MW absorption in hexagonal ferrites‐based microwave absorption materials (MAMs) regulates their EM characteristics, improves impedance matching, and creates a diversity of loss mechanisms. In addition, the limitations, challenges, and opportunities of hexagonal ferrites‐based MAMs are discussed, which will be helpful to those working in related areas. As a general application potential, it is worth mentioning that, as a result of recent promising findings in the synthesis of hexagonal ferrites‐based composites, hexaferrite‐based composites are suitable devices in the area of microwave absorption.

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“…The performance degradation of Solid Oxide Cells (SOCs) is one of the main drawbacks of this technology for energy production (fuel cell operation -SOFC) and hydrogen production (electrolyser cell operation -SOEC). The SOC degradation is ascribed to various material instabilities activated by the high operating temperature and the electrode polarization (1,2). Among these phenomena, the microstructural evolution within the hydrogen electrode made of nickel and yttria-stabilized zirconia (Ni-YSZ cermet) is recognized to contribute significantly to the global cell degradation.…”

Section: Introductionmentioning

confidence: 99%

Impact of Microstructure and Polarization on the Degradation of Ni-YSZ Electrode: An Experimental and Modeling Approach

et al. 2019

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Solid oxide cells with classical Ni-YSZ hydrogen electrodes were operated in fuel cell and electrolysis mode in order to assess the impact of the initial microstructure on the electrochemical and microstructural stability of the cermet. The pristine and aged electrodes have been reconstructed by synchrotron X-ray holotomography. The gradients in microstructural properties have been determined in the vicinity of the electrode/electrolyte interface and in the bulk of the electrodes. Significant Ni depletion was detected only in the electrochemically active region of the aged cells operated in electrolysis mode, while the volatilization is rather limited for the other samples. Besides, substantial Ni agglomeration was confirmed for all aged cermets. The electrode stability was found to depend on the initial electrode microstructure. The microstructural properties have been introduced in multi-scale models to estimate the impact of Ni evolution on the cell performance and to analyze the underlying causes of volatilization and agglomeration.

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Structural and electrical behavior evaluation of Ho-substituted Co2W hexagonal ferrites

Cited by 25 publications

References 25 publications

Synthesis, Magnetic and Electrical Characteristics of Ba‐Sr Hexaferrites Substituted with Samarium, Chromium and Aluminum

Synthesis, Magnetic and Electrical Characteristics of Ba‐Sr Hexaferrites Substituted with Samarium, Chromium and Aluminum

Recent Progress in Hexagonal Ferrites Based Composites for Microwave Absorption

Impact of Microstructure and Polarization on the Degradation of Ni-YSZ Electrode: An Experimental and Modeling Approach

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