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Journal of Materials Science & Technology 2022年第7期102卷 115-122页

作者： Yue-Yi Wang Song-Yang Wen-Jin Sun Kun Dai Ding-Xiang Yan Zhong-Ming Li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China

barium ferrite(BaFe_(12)O_(19))is considered as potential microwave absorption(MA)material thanks to the large saturation magnetization,high Curie temperature,and excellent chemical stability.The integration of carbon nanotube(CNT)can improve the dielectric loss of BaFe_(12)O_(19)for further enhanced MA perfor-mance,nevertheless,the MA performance is still not desirable because of the poor CNT dispersion in the CNT/BaFe_(12)O_(19)composites,which usually prepared via the ball-milling method,unless high CNT loading was used.Herein,according to the thermal stability of CNT in different atmosphere and the formation mechanism of BaFe_(12)O_(19)from precursor,CNT was introduced in the precursor of BaFe_(12)O_(19)uniformly during auto-ignition process and calcined under different atmosphere.When CNT loading is only 2.0 wt%,the CNT/BaFe_(12)O_(19)composites obtained exhibits a minimum reflection loss(RL_(min))of-43.9 dB and effective bandwidth(with RL<-10 dB)of 3.9 GHz with the thickness of 1.5 mm,which are much supe-rior to-10.2 dB and 2.2 GHz for pure BaFe_(12)O_(19),and-13.6 dB and 2.5 GHz for CNT/BaFe_(12)O_(19)composite prepared by ball-milling method.These results may pave the way to design high-performance BaFe_(12)O_(19)based microwave absorbers.

关键词： Carbon nanotube barium ferrite Microwave absorption

A neutron diffraction investigation of high valent doped barium ferrite with wideband tunable microwave absorption

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Journal of Advanced Ceramics 2022年第2期11卷 263-272页

作者： Jun LI Yang HONG San HE Weike LI Han BAI Yuanhua XIA Guangai SUN Zhongxiang ZHOU School of Physics Harbin Institute of TechnologyHarbin 150001China Heilongjiang Provincial Key Laboratory of Plasma Physics and Application Technology Harbin Institute of TechnologyHarbin 150001China School of Chemistry and Chemical Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory for Neutron Physics of CAEP Institute of Nuclear Physics and ChemistryMianyang 621999China

The barium ferrite BaTi_(x)Fe_(12−x)O_(19)(x=0.2,0.4,0.6,0.8)(BFTO-x)ceramics doped by Ti4+were synthesized by a modified sol–gel method.The crystal structure and magnetic structure of the samples were determined by neutron diffraction,and confirm that the BFTO-x ceramics were high quality single phase with sheet microstructure.With x increasing from 0.2 to 0.8,the saturation magnetization(M_(s))decreases gradually but the change trend of coercivity(H_(c))is complex under the synergy of the changed grain size and the magnetic crystal anisotropy field.Relying on the high valence of Ti^(4+),double resonance peaks are obtained in the curves of the imaginary part of magnetic conductivity(μ′′)and the resonance peaks could move toward the low frequency with the increase of x,which facilitate the samples perform an excellent wideband modulation microwave absorption property.In the x=0.2 sample,the maximum reflection loss(RL)can reach−44.9 dB at the thickness of only 1.8 mm,and the bandwidth could reach 5.28 GHz at 2 mm when RL is less than−10 dB.All the BFTO-x ceramics show excellent frequency modulation ability varying from 18(x=0.8)to 4 GHz(x=0.4),which covers 81%of the investigated frequency in microwave absorption field.This work not only implements the tunable of electromagnetic parameters but also broadens the application of high-performance microwave absorption devices.

关键词： barium ferrite neutron diffraction microwave absorption

The structural and magnetic properties of barium ferrite powders prepared by the sol-gel method

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Chinese Physics B 2012年第1期21卷 467-470页

作者：李颉张怀武李元勋刘颖力马岩冰 School of Microelectronics and Solid-State Electronics University of Electronic Science and Technology of ChinaChengdu 610054China

In this paper, M-type hexagonal barium ferrite powders are synthesized using the sol-gel method. A dried precursor heated in air is analyzed in the temperature range from 50 to 1200 ℃ using thermo-gravimetric analysis and differential scanning calorimetry. The effects of the additives and the cacinating temperature on the magnetic properties are investigated, and the results show that single-phase barium ferrite powders can be formed. After heat-treating at 950 ℃ for 4h with 3 wt% additive, the coercivity and saturation magnetization are found to be 440 Oe and 57.9 emu/g, respectively.

关键词： barium ferrite sol-gel method powder magnetic property

Perpendicularly oriented barium ferrite thin films with low microwave loss,prepared by pulsed laser deposition

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Chinese Physics B 2016年第6期25卷 581-584页

作者：陈大明李元勋韩莉坤龙超张怀武 College of Materials and Chemical Engineering Hainan University Haikou 570228 China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Chengdu 610054 China

barium ferrite（Ba M） thin films are deposited on platinum coated silicon wafers by pulsed laser deposition（PLD）.The effects of deposition substrate temperature on the microstructure,magnetic and microwave properties of Ba M thin films are investigated in detail.It is found that microstructure,magnetic and microwave properties of Ba M thin film are very sensitive to deposition substrate temperature,and excellent Ba M thin film is obtained when deposition temperature is 910℃ and oxygen pressure is 300 m Torr（1 Torr = 1.3332×102Pa）.X-ray diffraction patterns and atomic force microscopy images show that the best thin film has perpendicular orientation and hexagonal morphology,and the crystallographic alignment degree can be calculated to be 0.94.Hysteresis loops reveal that the squareness ratio（Mr/Ms） is as high as 0.93,the saturated magnetization is 4004 Gs（1 Gs = 104T）,and the anisotropy field is 16.5 kOe（1 Oe = 79.5775 A·m-1）.Ferromagnetic resonance measurements reveal that the gyromagnetic ratio is 2.8 GHz/kOe,and the ferromagnetic resonance linewith is108 Oe at 50 GHz,which means that this thin film has low microwave loss.These properties make the Ba M thin films have potential applications in microwave devices.

关键词： barium ferrite thin films magnetic properties

Magnetic properties and special morphology of barium ferrite via electrospinning

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Rare Metals 2017年第2期36卷 113-117页

作者： Gui-Fang Liu Run-Hua Fan Zi-Dong Zhang Jing Li Min Chen Qian-Qian Li Lu Lu Pei-Tao Xie Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationShandong UniversityJinan 250061China

barium ferrite micro-/nanofibers with special morphology,nanowires with diameters of 100 nm,nanoribbons with diameters of 1μm,and nanotubes with outer diameter of about 300 nm while inner diameter of 100 nm were successfully prepared via electrospinning using different solvents（dimethyl formamide（DMF）,solutions of deionized water and ethyl alcohol,and solutions of deionized water and acetic acid,respectively）.The barium ferrite micro-/nanofibers were characterized by scanning electron microscope（SEM）,X-ray diffraction analysis（XRD）,and vibration sample magnetometer（VSM）.The results demonstrate that the pure BaFe12O19 ferrite phase is successfully formed.And the SEM results show excellent morphologies.The magnetic hysteresis loops demonstrate that their magnetic properties are quite different with different morphologies.The specific saturation magnetization is approximately the same（46.12-49.17 A·m^2·kg^-1）,but the coercivity of the BaFe12O19 increases from wires（190.08 kA·m^-1）,ribbons（224.16 kA·m^-1） to tubes（258.88 kA·m^-1）.

关键词： Electrostatic spinning barium ferrite Hollow fiber Ribbon fiber

Texture and self-biased property of an oriented M-type barium ferrite thick film by tape casting

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Chinese Physics B 2012年第6期21卷 490-493页

作者：陈大明刘颖力李元勋杨楷张怀武 State Key Laboratory of Electronic Films and Integrated Devices University of Electronic Science and Technology of China

In this paper, the oriented M-type barium ferrite （BaM） thick films with different thicknesses are prepared by tape casting. It is found that the crystallographic alignment degree （f）, the pore and the squareness ratio （Mr/Ms） are not affected by the thickness of the film. XRD and SEM results show that the thick film has hexagonal morphology with a crystal texture of c-axis grains perpendicular to film plane. The hysteresis curve indicates that the BaM thick film exhibits a self-biased property with a remanent magnetization of 3.30 T, a squareness ratio （Mr/Ms） of 0.81, and a coercivity of 0.40 T. The results show that the BaM thick film has potential for use in self-biasing microwave devices, and also proves that the tape casting technique is capable of fabricating high-quality barium ferrite films, thus providing a unique opportunity to realize the large area production of thick film.

关键词： barium ferrite magnetic material thick films

Comparison of the Sol-gel Method with the Coprecipitation Technique for Preparation of Hexagonal barium ferrite

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Chemical Research in Chinese Universities 2008年第5期24卷 525-528页

作者： WANG Jing-ping LIU Ying ZHANG Mi-lin QIAO Ying-jie XIA Tian College of Materials Science and Chemical Engineering Harbin Engineering University Harbin 150001 P. R. China Laboratory of Functional Materials College of Chemistry and Chemical Technology Heilongfiang University Harbin 150080 P. R. China

Hexagonal barium ferrite BaFe12O19 particles were prepared by sol-gel and coprecipitation methods, respectively. The composition of the so-obtained materials was investigated by means of XRD. By the sol-gel method, non-anticipated intermediate crystalline phases, such as γ-Fe2O3, α-Fe2O3, BaCO3, and BaFe2O4 etc., were formed with the delay of the formation of BaFe12O19. The formation of single phase BaFe12O19 required calcination at 850 oC for 4 h. On the other hand, using coprecipitation technique, amorphous hydroxide precursor was directly transferred into BaFe12O19 almost without the formation of intermediate crystalline phases. BaFe12O19 was prepared by calcining at 700 oC for 3 h. The results were confirmed by ESEM and VSM analyses. Based on the already reported results and the observed results in this study, it can be concluded that the coprecipitaion technique is easier to control than the sol-gel method for preparation of BaFe12O19 at a low temperature.

关键词： Sol-gel Coprecipitation barium ferrite

Synthesis and Properties of Tubular Polyaniline-barium ferrite Composite

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Journal of Electronic Science and Technology of China 2007年第4期5卷 296-299页

作者： Yuan-Xun Li Ying-Li Liu Jie Li Fa-Ming Long Jian-Hong Kang School of Mieroelectronics and Solid-State Electronics University of Electronic Science and Technology of China （UESTC） Chengdu 610054 China

The polyaniline-barium ferrite composite was synthesized by in situ polymerization of aniline in the presence of BaFe12019 nanoparticles. The structure, morphology, and magnetic properties of samples were characterized by powder X-ray diffraction （XRD）, Fourier transform infrared （FTIR）, scanning electron microscopy （SEM） and vibrating sample magnetometer （VSM）. The testing results showed that the composite exhibited the ferromagnetic and electric behaviors, which benefit for the application of electromagnetic interfence.

关键词： barium ferrite magnetic materials polyaniline synthesis.

Effect of BaSO_(4) on phase composition and sintering process of iron ore fines

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Journal of Iron and Steel Research(International) 2022年第3期29卷 408-417页

作者： Jian-tao Ju Chen-mei Tang Guang-heng Ji Xiang-dong Xing Gui-qing Zhao Xin-tai Jiang Feng-lin Lu School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina Research Center of Metallurgical Engineering and Technology of Shaanxi Xi’an University of Architecture and TechnologyXi’an710055ShaanxiChina JISCO Iron and Steel Research Institute Jiayuguan735100ShaanxiChina

Iron ore containing BaSO_(4) may have a series of effects on the quality of the sinter and performance of the blast furnace.Thus,the effect mechanism of BaSO_(4)(0-6.0 mass%)on the compressive strength,mineral composition,and microstructure of the sinter was investigated.The experimental results show that the compressive strength of the sintered samples initially increases and then decreases when the BaSO_(4) content increases from 0 to 6.0 mass%,reaching a peak value of 12.78 kN with a BaSO_(4) content of 1.0 mass%.Thermal analysis indicates that BaSO_(4) initially decomposes to produce BaO at 1468 K in the presence of iron ore.BaO combines with Fe_(2)O_(3) forming barium ferrite(Ba_(2)Fe_(6)O_(11)),which exists in the sintered sample with a granular form.BaO also dissolves in calcium ferrite and slag to promote the formation of calcium ferrite and barium glass,respectively.The content of needle-like calcium ferrite gradually increases and then decreases with the increase in BaSO_(4) content.Hematite exists in a plate-like form.The generation of dicalcium ferrite is promoted by increasing the BaSO_(4) addition from 2.0 to 6.0 mass%.

关键词： Sinter barium sulfate Hematite barium ferrite Mineral structure

Precursor-directed synthesis of quasi-spherical barium ferrite nanoparticles with good dispersion and superior magnetic properties

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Precursor-directed synthesis of quasi-spherical barium ferri...