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 characterize...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.展开更多
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 ...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.展开更多
A series of doped barium hexaferrites BaFe12-2xMnxSnxO19 （x = 0.0-1.0） particles were prepared by the co-precipitation/molten salt method. The particle size and crystalline of the samples BaFe12-2xMnxSnxO19 decrease...A series of doped barium hexaferrites BaFe12-2xMnxSnxO19 （x = 0.0-1.0） particles were prepared by the co-precipitation/molten salt method. The particle size and crystalline of the samples BaFe12-2xMnxSnxO19 decrease with an increase in the doping amount x. When x is less than 0.8, the pure BaFe12-2xMnxSnxO19 particles with hexagonal plate morphology are obtained. The effects of substitution on magnetic properties were evaluated and compared to nomal BaFe12O19. The specific magnetizations （Ms） of doped materials have been significantly improved. Among all these compositions, the BaFe10.4Mn0.8Sn0.8O19 sample has the highest Ms value of 81.8 A？m2？kg-1 at room temperature and its intrinsic coercivity （Hc） is 44.5 kA？m-1. The as-prepared doped barium ferrites exhibit a low temperature coefficient of coercivity close to zero. The coercivity is independent of temperature when x is in the a range 0.5-0.7.展开更多
In this paper, the nanometer permanent magnetic BaFe12O19 powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO3)2, Fe(N...In this paper, the nanometer permanent magnetic BaFe12O19 powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO3)2, Fe(NO3)2 and NH4HCO3·NH2COONH4 were used as starting materials. The effect of crystallization process and heat treatment conditions on the particle size, microstructure and magnetic properties of powder was studied by using XRD, TEM and vibration sample magnetometometer techniques.XRD results showed that the hematite, α Fe2O3, was the main phase in the powder at heat treatment temperatures below 650℃ and its amount in the powder was decreased with increasing temperature and small amount of α Fe2O3 was still remained after being heated at 900℃ for 8hrs. BaFe12O19 was formed about 650℃ and its amount increased in the powder as temperature raised and the higher temperature was needed to attain considerable amount of BaFe12O19 and ideal nanometer BaFe12O19 particle in the powder. The temperature between 40℃～60℃ in the crystallization process was favor to the formation of good BaFe12O19 crystal and to the good magnetic properties of the powder. TEM showed that the particle size in the powder increased with the enhancement of the temperature and the powder crystallized at 40℃ and heated at 800℃ for 8hrs afterwards had a very homogenous particle size distribution, and that the powder heated at 900℃ for 8hrs with the same crystalline condition as the former had a typical hexagonal shape and a chain aggregation. Specific saturation and residential magnetizations and coercive force of the powder increased monotonically with the increase of temperature, and reached 39.86A·m2·kg-1, 23.96A·m2·kg-1, 480kA·m-1 at 900℃, respectively.展开更多
基金This work was supported by the National Nature Science Foundation of China under Grant No.60425102.
文摘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.
基金Project supported by the Foundation of the Ministry of Science and Technology of China (Grant No. 2009GJE00033)the National Natural Youth Fund of China (Grant No. 61001025)the National Program for Science and Technology Development of Guangdong Province,China (Grant No. 2010B090400314)
文摘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.
基金Funded by National Natural Science Foundation of China (Nos.20801016, 20701013, and 60971020)Postdoctoral Foundation of Heilongjiang Province(No. LRB07-231)Fundamental Research Funds for the Central Universities(No.HEUCF201210010)
文摘A series of doped barium hexaferrites BaFe12-2xMnxSnxO19 （x = 0.0-1.0） particles were prepared by the co-precipitation/molten salt method. The particle size and crystalline of the samples BaFe12-2xMnxSnxO19 decrease with an increase in the doping amount x. When x is less than 0.8, the pure BaFe12-2xMnxSnxO19 particles with hexagonal plate morphology are obtained. The effects of substitution on magnetic properties were evaluated and compared to nomal BaFe12O19. The specific magnetizations （Ms） of doped materials have been significantly improved. Among all these compositions, the BaFe10.4Mn0.8Sn0.8O19 sample has the highest Ms value of 81.8 A？m2？kg-1 at room temperature and its intrinsic coercivity （Hc） is 44.5 kA？m-1. The as-prepared doped barium ferrites exhibit a low temperature coefficient of coercivity close to zero. The coercivity is independent of temperature when x is in the a range 0.5-0.7.
文摘In this paper, the nanometer permanent magnetic BaFe12O19 powder was synthesized by a novel method of independent nucleation and crystallization steps and subsequent heat treatment,during the synthesis, Ba(NO3)2, Fe(NO3)2 and NH4HCO3·NH2COONH4 were used as starting materials. The effect of crystallization process and heat treatment conditions on the particle size, microstructure and magnetic properties of powder was studied by using XRD, TEM and vibration sample magnetometometer techniques.XRD results showed that the hematite, α Fe2O3, was the main phase in the powder at heat treatment temperatures below 650℃ and its amount in the powder was decreased with increasing temperature and small amount of α Fe2O3 was still remained after being heated at 900℃ for 8hrs. BaFe12O19 was formed about 650℃ and its amount increased in the powder as temperature raised and the higher temperature was needed to attain considerable amount of BaFe12O19 and ideal nanometer BaFe12O19 particle in the powder. The temperature between 40℃～60℃ in the crystallization process was favor to the formation of good BaFe12O19 crystal and to the good magnetic properties of the powder. TEM showed that the particle size in the powder increased with the enhancement of the temperature and the powder crystallized at 40℃ and heated at 800℃ for 8hrs afterwards had a very homogenous particle size distribution, and that the powder heated at 900℃ for 8hrs with the same crystalline condition as the former had a typical hexagonal shape and a chain aggregation. Specific saturation and residential magnetizations and coercive force of the powder increased monotonically with the increase of temperature, and reached 39.86A·m2·kg-1, 23.96A·m2·kg-1, 480kA·m-1 at 900℃, respectively.
基金supported by the National Natural Science Foundation of China(Grant Numbers 51702285,51772269)the Zhejiang Provincial Natural Science Foundation(Grant Number LY17F040003).
