Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a...Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite materials.This paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent years.The emergence of new raw material,the advancement of perparation methods and manufacturing techniques,and the potential applications of permanent ferrite materials are introduced and discussed.Specifically,nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources,and therefore it could be a promising development trendency.展开更多
Crystalline Co nanocomposites in the rutile TiO2 were synthesized by 180 keV Co ion beam implantation at temperature of 623 K with the fluence of 4×10^16 cm^-2. The structural and magnetic properties of samples w...Crystalline Co nanocomposites in the rutile TiO2 were synthesized by 180 keV Co ion beam implantation at temperature of 623 K with the fluence of 4×10^16 cm^-2. The structural and magnetic properties of samples with different thermal treatment were characterized by synchrotron radiation X-ray diffraction （SR-XRD）, high resolution transmission electron mi- croscopy （HRTEM）, Rutherford backscattering/channeling and the superconducting quantum interference device magnetometer. The SR-XRD results reveal the formation of hcp and fce phases of Co clusters, and the SR-XRD and HRTEM show that Co nanocrystals （NCs） have been formed in TiO2 after ion implantation. With increasing of annealing temperature, the transition of hcp to fcc Co is observed, and the Co NCs sizes were increased with increasing post-annealing temperature. At annealing temperature 1073 K, the lattice damaged is significantly removed compared with the virgin sample. The Co NCs forming inside TiO2 are the major contribution of the measured ferromagnetism.展开更多
The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The ef...The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.展开更多
Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin...Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.展开更多
We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid...We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid process. Experimental results also indicate that previous immersion of the substrates in a solution of oxalic acid causes the grown nanowires to convert gradually into magnetite （Fe3O4） nanowires. Additionally, the saturated state of Fe3O4 nanowires is achieved as the oxalic acid concentration reaches 0.75 mol/L. The average diameter and length of nanowires expands with an increasing operation temperature and the growth density of nanowires accumulates with an increasing gas flux in the vapor-solid process. The growth mechanism of a-Fe2O3 and Fe3O4 nanowires is also discussed. The results demonstrate that the entire synthesis of nanowires can be completed within 2 h.展开更多
In this letter, the transmission probability and the conductance of the ballistic electron are studied in a nanostructure with the periodic magnetic-electric barriers. We find that the resonant splitting increases wit...In this letter, the transmission probability and the conductance of the ballistic electron are studied in a nanostructure with the periodic magnetic-electric barriers. We find that the resonant splitting increases with the number of periods increasing, so the number of the resonant peaks increases and the peaks become sharper. For the m-th periodic magnetic-electric barriers tunneling the splitting is （m - 1）-fold.展开更多
Mossbauer spectroscopy was established as an analytical method 50 years ago and it is still of current interest in many disciplines as mineralogy, environmental science, archeology and biology. Areas of research where...Mossbauer spectroscopy was established as an analytical method 50 years ago and it is still of current interest in many disciplines as mineralogy, environmental science, archeology and biology. Areas of research where Mossbauer spectroscopy is contributing are metals and alloys, magnetic materials, chemical compounds and oxidation states, nanoparticles and many others. Different types of amorphous and nanocrystalline materials （e.g. finemet, nanoperm and hitperm） can be analyzed under different external influence like neutron irradiation or external magnetic field. Mineralogical samples as potassium white micas in sheared basement cover rocks from the Central Western Carpathians and meteorites can be also effectively investigated using MOssbauer spectroscopy. Phase analysis of meteorites can be helpful in their classification and moreover, particular magnetic and non-magnetic components can be analyzed in details. At present, the Mossbauer spectroscopy is also used to analyze environmental materials like zeolites, volcanic tephra and compounds containing ferrate （Fe6＋）.展开更多
Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3...Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3O4 magnetic nanoparticles were synthesized with pH value, temperature, and the dosage of surfactant. The phase, structure, size and magnetism of nanoparticles were tested by X-ray diffration （XRD）, transmission electron microscopy （TEM） and magnetic balance. On the basis of the surface modification coating mechanism, the experimental phenomena and the effects on the variation of size, magnetism and stability of Fe3O4 nanoparticles were theoretically analyzed. X-Ray diffraction spectrum and TEM photograph show that 1） the nanoparticles structure is perfect, 2） the diameter of narnoparticles is small and have good deliquescence, and 3） Sodium oleate is the anion surfactant. Therefore 1） the good condition of surface modification is in an acidic solution, 2） the best temperature of surface modification is at 80 ℃, and 3） the dosage of surfactant should be about 0.6 times of that of Fe^2＋.展开更多
Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites ...Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 ℃for 3 d. A variety of mass ratios of Fe2O3/SiO2 was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 20 from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO2 amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites （360-390 m^2/g）. This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.展开更多
Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characterist...Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively.展开更多
Composite biomaterials with controllable mi- crostructures play an increasingly important role in tissue engineering and regenerative medicine. Here, we report a magnetic hydrogel composite with disk-like microstructu...Composite biomaterials with controllable mi- crostructures play an increasingly important role in tissue engineering and regenerative medicine. Here, we report a magnetic hydrogel composite with disk-like microstructure fabricated by assembly of iron oxide nanopartides during the gelation process in the presence of rotating magnetic field. It should be mentioned that the iron oxide nanoparticles here were synthesized identically following techniques of Fer- umoxytol that is the only inorganic nanodrug approved by FDA for clinical applications. The microstructure of nano- particles inside the hydrogel was ordered three-dimensionally due to the twist of the aligned chains of magnetic nano- particles which leads to the lowest state of systematic energy. The size of microstructure can be tuned from several micro- meters to tens of micrometers by changing the assembly parameters. With the increase of microstructure size, the magnetothermal anisotropy was also augmented. This result confirmed that the assembly-induced anisotropy can occur even for the several micron aggregates of nanopartides. The rotating magnetic field-assisted technique is cost-effective, simple and flexible for the fabrication of composite hydrogel with ordered microstructure. We believe it will be favorable for the quick, green and intelligent fabrication of some com- posite materials.展开更多
基金Project(1053320222852)supported by the Graduate Student Innovation Program of Central South University,China。
文摘Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite materials.This paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent years.The emergence of new raw material,the advancement of perparation methods and manufacturing techniques,and the potential applications of permanent ferrite materials are introduced and discussed.Specifically,nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources,and therefore it could be a promising development trendency.
基金The work was supported by the National Natural Science Foundation of China （No.10875004 and No.11005005）, and National Basic Research Program of China （No.2010CB832904）, the 2011 Self-Raised Funds Project of HeBei Science and Technology Bureau （No.11316736）, and the 2011 Key Project of the Langfang Teachers College （No.LSZZ201101）.
文摘Crystalline Co nanocomposites in the rutile TiO2 were synthesized by 180 keV Co ion beam implantation at temperature of 623 K with the fluence of 4×10^16 cm^-2. The structural and magnetic properties of samples with different thermal treatment were characterized by synchrotron radiation X-ray diffraction （SR-XRD）, high resolution transmission electron mi- croscopy （HRTEM）, Rutherford backscattering/channeling and the superconducting quantum interference device magnetometer. The SR-XRD results reveal the formation of hcp and fce phases of Co clusters, and the SR-XRD and HRTEM show that Co nanocrystals （NCs） have been formed in TiO2 after ion implantation. With increasing of annealing temperature, the transition of hcp to fcc Co is observed, and the Co NCs sizes were increased with increasing post-annealing temperature. At annealing temperature 1073 K, the lattice damaged is significantly removed compared with the virgin sample. The Co NCs forming inside TiO2 are the major contribution of the measured ferromagnetism.
基金Project(2013DFA51290)supported by International S&T Cooperation Program of China
文摘The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.
文摘Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.
文摘We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid process. Experimental results also indicate that previous immersion of the substrates in a solution of oxalic acid causes the grown nanowires to convert gradually into magnetite （Fe3O4） nanowires. Additionally, the saturated state of Fe3O4 nanowires is achieved as the oxalic acid concentration reaches 0.75 mol/L. The average diameter and length of nanowires expands with an increasing operation temperature and the growth density of nanowires accumulates with an increasing gas flux in the vapor-solid process. The growth mechanism of a-Fe2O3 and Fe3O4 nanowires is also discussed. The results demonstrate that the entire synthesis of nanowires can be completed within 2 h.
文摘In this letter, the transmission probability and the conductance of the ballistic electron are studied in a nanostructure with the periodic magnetic-electric barriers. We find that the resonant splitting increases with the number of periods increasing, so the number of the resonant peaks increases and the peaks become sharper. For the m-th periodic magnetic-electric barriers tunneling the splitting is （m - 1）-fold.
文摘Mossbauer spectroscopy was established as an analytical method 50 years ago and it is still of current interest in many disciplines as mineralogy, environmental science, archeology and biology. Areas of research where Mossbauer spectroscopy is contributing are metals and alloys, magnetic materials, chemical compounds and oxidation states, nanoparticles and many others. Different types of amorphous and nanocrystalline materials （e.g. finemet, nanoperm and hitperm） can be analyzed under different external influence like neutron irradiation or external magnetic field. Mineralogical samples as potassium white micas in sheared basement cover rocks from the Central Western Carpathians and meteorites can be also effectively investigated using MOssbauer spectroscopy. Phase analysis of meteorites can be helpful in their classification and moreover, particular magnetic and non-magnetic components can be analyzed in details. At present, the Mossbauer spectroscopy is also used to analyze environmental materials like zeolites, volcanic tephra and compounds containing ferrate （Fe6＋）.
文摘Nanometer particles are important portion of magnetic fluid. Fe3O4 magnetic nanoparticles were studied in this paper and the surface modification of Fe3O4 nanoparticles was investigated by a series of experiments. Fe3O4 magnetic nanoparticles were synthesized with pH value, temperature, and the dosage of surfactant. The phase, structure, size and magnetism of nanoparticles were tested by X-ray diffration （XRD）, transmission electron microscopy （TEM） and magnetic balance. On the basis of the surface modification coating mechanism, the experimental phenomena and the effects on the variation of size, magnetism and stability of Fe3O4 nanoparticles were theoretically analyzed. X-Ray diffraction spectrum and TEM photograph show that 1） the nanoparticles structure is perfect, 2） the diameter of narnoparticles is small and have good deliquescence, and 3） Sodium oleate is the anion surfactant. Therefore 1） the good condition of surface modification is in an acidic solution, 2） the best temperature of surface modification is at 80 ℃, and 3） the dosage of surfactant should be about 0.6 times of that of Fe^2＋.
基金Project(RP021-2012C)supported by University of Malaya under the UMRG Fund,Malaysia
文摘Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 ℃for 3 d. A variety of mass ratios of Fe2O3/SiO2 was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 20 from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO2 amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites （360-390 m^2/g）. This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.
基金Project(51104007)supported by the National Natural Science Foundation of ChinaProject(2132046)supported by Beijing Natural Science Foundation,China
文摘Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively.
基金supported by the National Key Research and Development Program of China(2017YFA0104301)the Fundamental Research Funds for the Central Universitiesthe supports from Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Composite biomaterials with controllable mi- crostructures play an increasingly important role in tissue engineering and regenerative medicine. Here, we report a magnetic hydrogel composite with disk-like microstructure fabricated by assembly of iron oxide nanopartides during the gelation process in the presence of rotating magnetic field. It should be mentioned that the iron oxide nanoparticles here were synthesized identically following techniques of Fer- umoxytol that is the only inorganic nanodrug approved by FDA for clinical applications. The microstructure of nano- particles inside the hydrogel was ordered three-dimensionally due to the twist of the aligned chains of magnetic nano- particles which leads to the lowest state of systematic energy. The size of microstructure can be tuned from several micro- meters to tens of micrometers by changing the assembly parameters. With the increase of microstructure size, the magnetothermal anisotropy was also augmented. This result confirmed that the assembly-induced anisotropy can occur even for the several micron aggregates of nanopartides. The rotating magnetic field-assisted technique is cost-effective, simple and flexible for the fabrication of composite hydrogel with ordered microstructure. We believe it will be favorable for the quick, green and intelligent fabrication of some com- posite materials.
