The easy-plane anisotropy of the Y_(2)Co_(17)rare earth soft magnetic alloy has high saturation magnetization and operating frequency,and good impedance matching.Therefore,it is expected to become a kind of high-perfo...The easy-plane anisotropy of the Y_(2)Co_(17)rare earth soft magnetic alloy has high saturation magnetization and operating frequency,and good impedance matching.Therefore,it is expected to become a kind of high-performance microwave absorbing material.In this paper,Y_(2)Co_(17)alloy was prepared by a reduction-diffusion method,and its micropowder was prepared as polyurethane(PU)based composite absorbing materials(Y_(2)Co_(17)/PU composites).The microwave properties of composites with different volume fractions were calculated.The composites showed outstanding absorption characteristics in the range of 20-30 vol%,and the minimum reflection loss(RL)was less than-50 d B.When the volume fraction was25%,the effective absorption bandwidth could cover the X-band at a thickness of 1.5 mm,and the Ku-band at a thickness of1.08 mm.The absorption mechanism was analyzed by the interface reflection model.The RL absorption peak bandwidth mechanism was discussed by using the amplitude relation and calculating the effective absorption bandwidth at different thicknesses.The effective absorption bandwidth values were in good agreement with the theoretical expectation.展开更多
Intermetallic complexes of rare-earth and 3d transition metals with core-shell structures are commonly employed as microwave absorbing materials due to their high saturation magnetizations and natural resonance in GHz...Intermetallic complexes of rare-earth and 3d transition metals with core-shell structures are commonly employed as microwave absorbing materials due to their high saturation magnetizations and natural resonance in GHz. Hence, we synthesized Y_2Co_(17)alloy via the co-precipitation reduction-diffusion technique, then coated the Y_2Co_(17)magnetic powders with SiO_(2)to create Y_2Co_(17)@SiO_(2) core-shell structures. The formation of Y_2Co_(17)@SiO_(2)/polyurethane(PU) at various volume fractions and their magnetic, electromagnetic properties were investigated using x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and vector network analyzer. The microwave absorption characteristics of Y_2Co_(17)@SiO_(2)/PU were also investigated at various volume fractions. We not only investigate the zero-reflection conditions of the samples with different volume fractions, but also show that every absorber has a strong reflection loss value(RL ≤-65.00 d B) and excellent microwave absorption properties with an average RL of Y_2Co_(17)@SiO_(2)/PU being below-10 d B at 8 GHz–18 GHz under different thicknesses, showing that the enhancement of microwave absorption performance arises from the balance between permeability and permittivity of absorber.展开更多
基金Project supported by the National Key R&D Program of China(Grant No.2021YFB3501302)the National Natural Science Foundation of China(Grant No.51731001)supported by the State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization’s key of research and development projects。
文摘The easy-plane anisotropy of the Y_(2)Co_(17)rare earth soft magnetic alloy has high saturation magnetization and operating frequency,and good impedance matching.Therefore,it is expected to become a kind of high-performance microwave absorbing material.In this paper,Y_(2)Co_(17)alloy was prepared by a reduction-diffusion method,and its micropowder was prepared as polyurethane(PU)based composite absorbing materials(Y_(2)Co_(17)/PU composites).The microwave properties of composites with different volume fractions were calculated.The composites showed outstanding absorption characteristics in the range of 20-30 vol%,and the minimum reflection loss(RL)was less than-50 d B.When the volume fraction was25%,the effective absorption bandwidth could cover the X-band at a thickness of 1.5 mm,and the Ku-band at a thickness of1.08 mm.The absorption mechanism was analyzed by the interface reflection model.The RL absorption peak bandwidth mechanism was discussed by using the amplitude relation and calculating the effective absorption bandwidth at different thicknesses.The effective absorption bandwidth values were in good agreement with the theoretical expectation.
基金the National Key Research and Development Program of China (Grant No. 2021YFB3501302)the National Natural Science Foundation of China (Grant No. 51731001)the Fund from the State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization’s Key Research and Development Projects。
文摘Intermetallic complexes of rare-earth and 3d transition metals with core-shell structures are commonly employed as microwave absorbing materials due to their high saturation magnetizations and natural resonance in GHz. Hence, we synthesized Y_2Co_(17)alloy via the co-precipitation reduction-diffusion technique, then coated the Y_2Co_(17)magnetic powders with SiO_(2)to create Y_2Co_(17)@SiO_(2) core-shell structures. The formation of Y_2Co_(17)@SiO_(2)/polyurethane(PU) at various volume fractions and their magnetic, electromagnetic properties were investigated using x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and vector network analyzer. The microwave absorption characteristics of Y_2Co_(17)@SiO_(2)/PU were also investigated at various volume fractions. We not only investigate the zero-reflection conditions of the samples with different volume fractions, but also show that every absorber has a strong reflection loss value(RL ≤-65.00 d B) and excellent microwave absorption properties with an average RL of Y_2Co_(17)@SiO_(2)/PU being below-10 d B at 8 GHz–18 GHz under different thicknesses, showing that the enhancement of microwave absorption performance arises from the balance between permeability and permittivity of absorber.
