Magnetic properties of Co and Ti co-doped strontium hexaferrite prepared by sol–gel method

Zhang, Min; Liu, Qiangchun; Zhu, Guangping; Xu, Shaohai

doi:10.1007/s00339-019-2500-5

Cited by 22 publications

(2 citation statements)

References 27 publications

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“…The decreased H C of Co–Ti doped SrM is related to the spin rearrangement by Co 2+ and Ti 4+ ion substitutions. In particular, Co 2+ –Ti 4+ substituted at the 2b site reduces the uniaxial anisotropy so that the coercive field is greatly reduced according to the Co–Ti doping concentration [ 65 , 76 , 77 ]. The increased H C of Al doped SrM is related to an enhancement of the magneto-crystalline anisotropy constant due to the substituted Al 3+ ions at the 12 k site [ 58 , 59 , 78 ].…”

Section: Ferromagnetic Resonance Frequency Tunable M-type Strontium F...mentioning

confidence: 99%

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

et al. 2023

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Although there is a high demand for absorption-dominant electromagnetic interference (EMI) shielding materials for 5G millimeter-wave (mmWave) frequencies, most current shielding materials are based on reflection-dominant conductive materials. While there are few absorption-dominant shielding materials proposed with magnetic materials, their working frequencies are usually limited to under 30 GHz. In this study, a novel multi-band absorption-dominant EMI shielding film with M-type strontium ferrites and a conductive grid is proposed. This film shows ultralow EMI reflection of less than 5% in multiple mmWave frequency bands with sub-millimeter thicknesses, while shielding more than 99.9% of EMI. The ultralow reflection frequency bands are controllable by tuning the ferromagnetic resonance frequency of M-type strontium ferrites and composite layer geometries. Two examples of shielding films with ultralow reflection frequencies, one for 39 and 52 GHz 5G telecommunication bands and the other for 60 and 77 GHz autonomous radar bands, are presented. The remarkably low reflectance and thinness of the proposed films provide an important advancement toward the commercialization of EMI shielding materials for 5G mmWave applications.

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Section: Ferromagnetic Resonance Frequency Tunable M-type Strontium F...mentioning

confidence: 99%

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

et al. 2023

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“…However, the wet impregnation method is complex to operate and the precursor is expensive . And traditional metal exsolution also has obvious drawbacks. − For example, for the standard composition of perovskite materials, the exsolved proportion of highly catalytically active metals is limited. An excessive exsolution (or high proportion) of metal can damage the perovskite structure and cause structural collapse.…”

Section: Introductionmentioning

confidence: 99%

B-Site Super-Excess Design Sr₂V_0.4Fe_0.9Mo_0.7O_6−δ-Ni_0.4 as a Highly Active and Redox-Stable Solid Oxide Fuel Cell Anode

Song,

Chen,

Pan

et al. 2023

ACS Appl. Mater. Interfaces

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In-situ exsolution type perovskites as solid oxide fuel cell (SOFCs) anode materials have received widespread attention because of their excellent catalytic activity. In this study, excessive NiO is introduced to the Sr2V0.4Fe0.9Mo0.7O6−δ (SVFMO) perovskite with the B-site excess design, and in-situ growth of FeNi3 alloy nanoparticles is induced in the reducing atmosphere to form the Sr2V0.4Fe0.9Mo0.7O6−δ-Ni0.4 (SVFMO-Ni0.4) composite anode. Here, with H2 or CH4 as SOFCs fuel gas, the formation of FeNi3 nanoparticles further enhances the catalytic ability. Compared with SVFMO, the maximum power density (P max) of Sr2V0.4Fe0.9Mo0.7O6−δ-Ni0.4 (SVFMO-Ni0.4) increases from 538 to 828 mW cm–2 at 850 °C with hydrogen as the fuel gas, and the total polarization resistance (R P) decreases from 0.23 to 0.17 Ω cm2. In addition, the long-term operational stability of the SVFMO-Ni0.4 anode shows no apparent performance degradation for more than 300 h. Compared with SVFMO, the P max of SVFMO-Ni0.4 increases from 138 to 464 mW cm–2 with methane as fuel gas, and the R P decreases from 1.21 to 0.29 Ω cm2.

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Theoretical Study of the Co‐doping Effects at Sr and Fe Sites on the Magnetic and Optical Properties of SrFe₁₂O₁₉

Apostolova,

Apostolov,

Wesselinowa

2024

Physica Status Solidi (b)

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For the first time, the magnetic and optical (bandgap) properties of co‐doped Mg/Dy, Al/Dy, and Mn/Nd (SFO) at Sr and Fe sites are investigated using a microscopic model and the Green's function theory. It is shown that the co‐doping at both Sr and Fe sites can change the behavior of the magnetization which decreases by transition metal or nonmagnetic ion doping at the Fe site (with doping ions larger than the host Fe ions), but by additive co‐doping at the Sr site with rare‐earth ion (which ionic radius is smaller than that of Sr) the magnetization increases with increasing the co‐doping concentration. The bandgap energy decreases in the co‐doped SFO. The mechanism of this co‐doping effect is explained on microscopic level. It is due to the changes of the spin‐exchange interaction constants at the doped sites caused by the appearance of different strain by the doping with two ions. The theoretical results are compared with the existing experimental data and are in good qualitative agreement.

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Magnetic properties of Co and Ti co-doped strontium hexaferrite prepared by sol–gel method

Cited by 22 publications

References 27 publications

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

B-Site Super-Excess Design Sr₂V_0.4Fe_0.9Mo_0.7O_6−δ-Ni_0.4 as a Highly Active and Redox-Stable Solid Oxide Fuel Cell Anode

Theoretical Study of the Co‐doping Effects at Sr and Fe Sites on the Magnetic and Optical Properties of SrFe₁₂O₁₉

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Magnetic properties of Co and Ti co-doped strontium hexaferrite prepared by sol–gel method

Cited by 22 publications

References 27 publications

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

B-Site Super-Excess Design Sr2V0.4Fe0.9Mo0.7O6−δ-Ni0.4 as a Highly Active and Redox-Stable Solid Oxide Fuel Cell Anode

Theoretical Study of the Co‐doping Effects at Sr and Fe Sites on the Magnetic and Optical Properties of SrFe12O19

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B-Site Super-Excess Design Sr₂V_0.4Fe_0.9Mo_0.7O_6−δ-Ni_0.4 as a Highly Active and Redox-Stable Solid Oxide Fuel Cell Anode

Theoretical Study of the Co‐doping Effects at Sr and Fe Sites on the Magnetic and Optical Properties of SrFe₁₂O₁₉