JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2020
·Vol. 31
·期 16
·13469-13476
·
IF 2.22
Wang Li,Yang Chaoqun,Jin Hongjun,Hu Yue,Li Ji,Xu Shichong,Li Haibo
CoFe 2 O 4 /CoFe 2 nanocomposites with exchange coupling behavior have been obtained from a two-step process. First, CoFe 2 O 4 nanoparticles with size of 11 nm were synthesized using a co-precipitation method. And second, the as-synthesized CoFe 2 O 4 nanoparticles were reduced under mixed gas (Ar 95% + H 2 5%) for 1 h at different temperatures. The structure, phase, particle size, morphology, and magnetic properties with the reduction temperature were studied. X-ray diffraction and Mössbauer spectroscopy results show the whole process from pure CoFe 2 O 4 hard magnetic phase to pure CoFe 2 soft magnetic phase when the reduction temperature increases from 400 to 700 °C, and CoFe 2 O 4 /CoFe 2 hard/soft nanocomposites are obtained at 500 and 600 °C. Magnetic measurement result show there is a stronger exchange coupling interaction between CoFe 2 O 4 and CoFe 2 for the sample reduced at 500 °C, but not in the sample reduced at 600 °C. A giant 76% enhancement of the maximum magnetic energy product (BH) max compared with pure CoFe 2 O 4 will be of technological significance in the future.
研究领域:
材料科学
·
磁学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2020
·
IF 0
Guangguang Guan,Guojun Gao,Jun Xiang,Jingnan Yang,Lei Gong,Xin Chen,Yamei Zhang,Kaiyin Zhang,Xianfeng Meng
CoFe2/BaTiO3 hybrid nanofibers (CoFe2/BTO HNFs) have been synthesized via a simple single-spinneret electrospinning followed by a calcination and hydrogen-thermal reduction process for microwave absorption. Electromagnetic and microwave absorption properties of CoFe2/BTO HNFs with different compositions are compared with those of pure CoFe2 NFs and BTO NFs. The results reveal that the CoFe2/BTO HNFs with a CoFe2/BTO molar ratio of 7:3 exhibit superior microwave absorption properties with a higher intensity and a wider bandwidth at a smaller absorber thickness. An optimal reflection loss (RL) of −82.4 dB at 15.2 GHz and an effective absorption bandwidth (RL ≤ −20 dB) of 5.0 GHz (13.0–18 GHz) are obtained for a thin thickness of only 1.2 mm. Moreover, the absorption band with RL values less than −20 dB can be manipulated between 4.6 and 18 GHz through changing the coating thickness in the range 1.0–3.0 mm. The excellent microwave absorbing performance can be mainly attributed to the better balance between impedance matching and electromagnetic attenuation capacity deriving from the good synergistic effect between dielectric BTO and magnetic CoFe2 nanoparticles within a such one-dimensional hybrid heteronanostructure as well as the significantly improved interfacial polarization relaxation. Furthermore, the three-dimensional network structure interlinked by these HNFs also contribute to microwave absorption through additional dissipation pathways such as microcurrent, multiple reflections, and scattering. The optimized CoFe2/BTO HNFs may be a potential candidate for lightweight and highly efficient microwave absorbing materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
DALTON TRANSACTIONS
·
2021
·Vol. 50
·期 33
·11640-11649
·
IF 4.39
Zijian Liao,Mingliang Ma,Zhouyu Tong,Yuxin Bi,Kwok L. Chung,Mingtao Qiao,Yong Ma,Aijie Ma,Guanglei Wu,Xiang Zhong,Ranran Sun
New types of electromagnetic (EM) wave absorption materials with a light weight, strong absorption ability and wide absorption frequency have been widely explored. Nevertheless, it is still an intractable challenge to design the structure of the materials and rationalize multiple components. In this work, one-dimensional (1D) CoFe2/C@MoS2 composites were prepared via electrospinning technology, high-temperature carbonization and hydrothermal method. SEM and TEM images reveal that the as-prepared CoFe2/C fibers with a 1D structure are well coated with MoS2. The excellent absorption performance of the composites is mainly attributed to the 1D structure and the ideal impedance matching. CoFe2/C@MoS2 composites show strong absorption ability with an optimal reflection loss (RL) of −66.8 dB (13.28 GHz) at a matching thickness of 2.12 mm. Meanwhile, the composite possesses an effective absorption frequency range between 10.70 and 16.02 GHz with a bandwidth of 5.32 GHz. These results indicate that CoFe2/C@MoS2 composites will become promising lightweight and highly efficient MA materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
PubMed
高影响因子
ChemistrySelect
·
2023
·Vol. 8
·期 33
·e202301789
·
IF 2.1
Xiqiong Guo,Fangying Yuan,Peixi Wang,Runqiu Li,Hui Zheng
Graphical A nanocomposite consisting of CoFe 2 alloy functionalized few-layer graphene sheets (CoFe 2 /FLGs) were fabricated in this research. Various measurements confirm that the nanosized CoFe 2 alloy particles are evenly dispersed within the FLGs and possess significant electrocatalytic performance and recyclability for the ORR. Searching for a high-efficiency, recycled and cheap catalytic material for oxygen reduction reaction (ORR) is urgently needed in fuel cells. In this study, we successfully fabricated a nanocomposite consisting of CoFe 2 alloy functionalized few-layer graphene sheets (CoFe 2 /FLGs) by employing ferric nitrate, cobalt nitrate, and glucose as precursors. Various measurements conducted in this research confirm that the nanosized CoFe 2 alloy particles are evenly dispersed within the FLGs and possess significant magnetism. Electrochemical measurements reveal that the CoFe 2 /FLGs exhibit a high positive onset potential (0.901 V), follow a four-electron pathway, display a low Tafel slope (77.21 mV/dec), possess a low charge-transfer resistance (∼72 Ω), and exhibit strong methanol tolerance. Consequently, the resulting CoFe 2 /FLGs nanocomposite demonstrates excellent electrocatalytic performance and recyclability for the ORR, positioning it as a promising catalyst for fuel cells.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）