268results about How to "High magnetization" patented technology

A magnetoresistive sensor having a novel free layer and a method of producing the same are disclosed. The magnetoresistive sensor comprises a pinned layer, a barrier layer disposed over the pinned layer, and a free layer disposed over the barrier layer. The free layer comprises a first magnetic layer disposed over the barrier layer. The first magnetic layer has a positive spin polarization, a positive magnetostriction, and a polycrystalline structure. The free layer further comprises a second magnetic layer disposed over the first magnetic layer. The second magnetic layer has a negative magnetostriction and comprises at least cobalt (Co) and boron (B).

The invention relates to a process for separating a dispersed phase from a continuous phase comprising the steps of i) contacting said phases with an effective amount of nanoparticles; ii) applying a magnetic field gradient to the obtained system; iii) separating the obtained phases wherein said nanoparticles are of the core shell type, said core consists of a metal or alloy having soft magnetic properties and said shell contains a graphene layers which are optionally functionalized; to new nanoparticles and method of manufacturing such nanoparticles.

Monodisperse colloidal nanocrystal clusters of magnetite (Fe3O4) with tunable sizes from about thirty to about three hundred nanometers have been synthesized using a high-temperature hydrolysis process. The colloidal nanocrystal clusters are capped with polyelectrolytes, and highly water soluble. Each cluster is composed of many single magnetite crystallites, thus retaining the superparamagnetic behavior at room temperature. The combination of superparamagnetic property, high magnetization, and high water dispersibility makes the colloidal nanocrystal clusters ideal candidates for various important biomedical applications such as drug delivery and bioseparation. The present invention is further directed to methods for forming colloidal photonic crystals from both aqueous and nonaqueous solutions of the superparamagnetic colloidal nanocrystal clusters with an external magnetic field applied thereto. The diffraction of the photonic crystals can be tuned from near infrared to visible and further ultraviolet spectral region by varying the external magnetic field.

The present invention relates to method and device for detecting changes of a magnetic response of at least one magnetic particle in a carrier fluid. The method comprises: using a measuring procedure comprising measuring the characteristic rotation time of said magnetic particle, said measuring procedure further involving measuring Brownian relaxation in said carrier fluid under influence of an external pulsed excitation magnetic field, and based on said influence of said external pulsed excitation magnetic field measuring a hydrodynamic volume of a particle or a change in a hydrodynamic volume of the particle change upon modification of an effective volume of the particle or its interaction with said carrier fluid by detecting change of magnetization of the particle with time by monitoring change of an output signal in detection coil.

The invention relates to the technical field of pipeline defect detection and discloses a pipeline defect and magnetic leakage detection device which comprises a central shaft, a magnetic conduction device and a flux leakage detection device, wherein a left leather cup and a right leather cup are fixedly installed at both ends of the central shaft through a flange disc and a pressure plate, the magnetic conduction device which can conduct magnetism to a pipeline to be detected is installed on the central shaft between the left leather cup and the right leather cup, and a flux leakage detection device which can detect magnetic leakage signals is installed at the outer side of the middle part of the magnetic conduction device. The invention has the advantages of reasonable and compact structure and convenient use, and can efficiently magnetize an oil pipe and enhance the magnetization strength of a pipe wall to be detected, thereby greatly enhancing the detection quality of defects of an oil pipeline and being not easy to generate blockage when passing through a variable diameter part of the pipeline because of favorable deformation by arranging a plate spring.

Embodiments disclosed herein include methods of modifying synthetic garnets used in RF applications to reduce or eliminate Yttrium or other rare earth metals in the garnets without adversely affecting the magnetic properties of the material. Some embodiments include substituting Bismuth for some of the Yttrium on the dodecahedral sites and introducing one or more high valency ions to the octahedral and tetrahedral sites. Calcium may also be added to the dodecahedral sites for valency compensation induced by the high valency ions, which could effectively displace all or most of the Yttrium (Y) in microwave device garnets. The modified synthetic garnets with substituted Yttrium (Y) can be used in various microwave magnetic devices such as circulators, isolators and resonators.

A ferrite carrier core material for electrophotography having a homogeneous composition, a certain surface property, a favorable fluidity, a high magnetization and a low resistance, and a ferrite carrier for electrophotography methods for producing them, and an electrophotographic developer using the ferrite carrier-core material, which exhibits a fast charge rising and a stable charge quantity with time, are provided. A ferrite carrier core material for electrophotography whose surface is divided by grooves or streaks into 2 to 50 regions per 10 μm and which has a manganese ferrite as a main component, and a method for producing the ferrite carrier core material for electrophotography using an Fe—Mn composite oxide as the raw material, and a method for producing a ferrite carrier for electrophotography are employed.

Contrast agents and methods for making them are presented that use Fe nanoparticles that produce higher clarity and particularity in MRI imaging. Various alloys and core compounds are presented that may be used to produce such higher clarity MRI images.

The invention provides a method for preparing a strontium ferrite magnetic powder with high specific saturation magnetization and high coercive force. Nitrates and chlorides of Sr, R Fe and M with limited amounts are dissolved, added with citric acid and ammonia gas to adjust the solution obtained to neutral or slightly alkaline so as to prepare sol; the sol is heated and evaporated to prepare gel, a precursor is prepared by self-propagating combustion, and the magnetic powder is obtained by calcining the precursor at a low temperature. In the composition, R is at least one of Y, La, Pr, Nd and Ce, and M is at least one of Co, Ni, Zn, Cu and Mn. In the method, the magnetic powder can be obtained by mixing, ball milling, calcining, fine grinding and annealing the precursor obtained by self-propagating combustion and at least one of the nano-grade SiO2, CaCO3, B2O3, SrSO4, Al2O3 and Cr2O3. The magnetic powder prepared by the technology has the specific saturation magnetization of 71-75emu / g and the coercive force of 5.5-6.5kOe. The magnetic powder is suitable for preparing bonded permanent magnets and automobile motor magnets requiring high magnetic property.

Disclosed are synthetic garnets and related devices that can be used in radio-frequency (RF) applications. In some embodiments, such RF devices can include garnets having reduced or substantially nil Yttrium or other rare earth metals. Such garnets can be configured to yield high dielectric constants, and ferrite devices, such as TM-mode circulators / isolators, formed from such garnets can benefit from reduced dimensions. Further, reduced or nil rare earth content of such garnets can allow cost-effective fabrication of ferrite-based RF devices. In some embodiments, such ferrite devices can include other desirable properties such as low magnetic resonance linewidths. Examples of fabrication methods and RF-related properties are also disclosed.

A manufacturing method of one dimension nano magnetic wires is provided. In the method, the one dimension nano magnetic wires having high magnetization and low coercive force are synthesized from a liquid by means of reduction with an applied magnetic field under normal atmospheric temperature and pressure. The one dimension nano magnetic wire is selected from the groups consisting of iron (Fe), cobalt (Co), nickel (Ni), and composites and an alloy thereof.

A magnetic memory element utilizing spin transfer switching includes a pinned layer, a tunneling barrier layer and a free layer structure. The tunneling barrier layer is disposed on the pinned layer. The free layer structure includes a composite free layer. The composite free layer includes a first free layer, an insert layer and a second free layer. The first free layer is disposed on the tunneling barrier layer and has a first spin polarization factor and a first saturation magnetization. The insert layer is disposed on the first free layer. The second free layer is disposed on the insert layer and has a second spin polarization factor smaller than the first spin polarization factor and a second saturation magnetization smaller than the first saturation magnetization. Magnetization vectors of the first free layer and the second free layer are arranged as parallel-coupled.

The invention discloses Fe@Fe3O4 nanoparticles having a photothermal function, and a preparation method and an application thereof, and belongs to the field of medical science materials. The preparation method is significantly characterized by comprising: firstly, utilizing octadecene as a solvent, utilizing Fe(CO)5 as an iron source, utilizing oleyl amine as a surfactant and a stabilizer, and preparing an Fe nanomaterial having good dispersity by high temperature pyrolysis; sequentially, adding (CH3)3NO at the high temperature for oxidization to form one layer of Fe3O4 shell on the surface layer of each Fe nanoparticle, and then improving water solubility by a ligand exchange method to obtain the Fe@Fe3O4 composite material as a photothermal reagent and having high magnetization strength. The composite material has the advantages of uniform particle size, high saturation magnetization strength, and controllable morphology, and has excellent dispersion and excellent stability in aqueous solution. The reaction time is short, the raw materials are easy to get, and operation processes are convenient. On the basis of the raw materials, the Fe@Fe3O4 nanoparticles are developed to connect PEG to the surface of the material, so that the Fe@Fe3O4 nanoparticles can be applied to biological bodies. The invention provides the application of the Fe@Fe3O4 nanoparticles in the field of tumor photothermal therapy.

The invention discloses a preparation method of a soft magnetic composite material. The surface of soft magnetic alloy powder is coated with a coating layer with a sol-gel method, wherein the coating layer is formed by nanometer Fe3O4 particles with the uniform sizes; the processes of bonding, compression molding and heat treatment are carried out, and the novel soft magnetic composite material is prepared. The preparation method has the advantages that the surface of the soft magnetic alloy powder can be uniformly coated with Fe3O4 prepared with the sol-gel method; the Fe3O4 with ferrimagnetism serves as an insulating coating agent, so that a magnetic dilution phenomenon occurring when a traditional non-magnetic material serves as a coating agent is avoided, and higher magnetic conductivity and magnetization intensity can be obtained.

Disclosed herein is a method for treating a brain disease in which focused ultrasound and magnetic targeting are applied to a subject in need of such treatment, so that therapeutic agent-magnetic nanoparticle composites are directed across the blood-brain barrier to a designated locus inside the brain of the subject. Each of the composites includes a magnetic nanoparticle that is formed of an iron-based core and a shell encapsulating the iron-based core, and a therapeutic agent that is bound to the shell of the magnetic nanoparticle. The magnetic nanoparticle has a size ranging from 5 to 200 nm. The iron-based core has a crystalline structure that imparts the composites with a sufficiently high magnetization, thereby enhancing magnetic targeting of the composites to the designated locus inside the brain of the subject. The magnetic targeting treatment is conducted via a magnet providing a magnetic flux density not less than 0.18 T.

The invention relates to a preparation method of water-dispersible graphene / ferroferric oxide (Fe3O4) composite powder. The method comprises the following steps of: (1) ultrasonically dispersing graphite oxide and sodium polystyrene sulfonate into water at room temperature to form reaction liquid, raising a temperature to 90 to 110 DEG C, and reacting for 8 to 16 hours; (2) adding ferric salt and ferrous salt into the reaction liquid under the protection of nitrogen atmosphere at room temperature, adding ammonia water, reducing the temperature to 70 to 90 DEG C, reacting for 20 to 40 minutes, and then adding an oleic acid for continuous reaction; and (3) cooling to room temperature, collecting the graphene / Fe3O4 composite powder by using a magnet, washing and drying to obtain the finished product. The method is simple and easy for industrial production; Fe3O4 in the prepared composite powder has pure crystalline phase; the Fe3O4 is well combined with the graphene; the Fe3O4 has good dispersibility on a surface of the graphene and in a layer of the graphene; the composite powder is low in resistivity, high in magnetic intensity and good in underwater dispersibility and has a good application prospect.

A magnetic recording system is disclosed in which the magnetization dynamics of the write head and recording medium are highly damped. The system may comprise a perpendicular recording head having a write pole, and a recording medium including a hard magnetic recording layer and a soft magnetic underlayer (SUL). The increased magnetic damping in the write pole and SUL suppresses precessional motion of the respective magnetizations, leading to a reduction in transition jitter caused by spurious head field fluctuations. The damping may be increased by providing films or multilayer structures that are doped with rare earth or transition metal elements. Exchange coupled laminates of doped and undoped layers may optimize both the effective damping and write field in the recording system.

The present invention relates to a composite bead and a fabrication method thereof, and particularly, to a porous composite bead comprising superparamagnetic cluster and nanoparticles, such as light-emitting nanoparticles, s magnetic nanoparticles, metallic nanoparticles, metal oxide nanoparticles and the like, and a fabrication method thereof.

Perpendicular magnetic recording media having a magnetic capping layer that is exchange coupled to an underlying perpendicular magnetic recording layer. The magnetic coupling layer is a granular layer having a high saturation magnetization (Ms). The perpendicular magnetic recording layer can include magnetic grains separated by an oxide grain boundary phase.

Employment of a carrier core material for an electrophotographic developer containing 0.8 to 5% by weight of Mg, 0.1 to 1.5% by weight of Ti, 60 to 70% by weight of Fe and 0.2 to 2.5% by weight of Sr and having an amount of Sr dissolved with a pH4 standard solution of 80 to 1000 ppm, a carrier using the core material and a process for producing them, and an electrophotographic developer using the carrier.

Approaches to improving the signal-to-noise ratio in a microwave-assisted magnetic recording hard disk drive over the entire region from the inner diameter to the outer diameter of the disk, especially in the context of shingled magnetic recording, include a narrower side gap on the side opposing a spin torque oscillator offset direction than the side gap in the offset direction, thereby increasing the gradient of the recording magnetic field in the cross-track direction and reducing the track edge noise of the recording pattern. Embodiments include use of a side shield on the side opposing the offset direction that has a higher saturation magnetization than the side shield on the side in the offset direction, thereby further increasing the gradient of the recording magnetic field in the cross-track direction.

The present invention provides the making process of homogeneous superparamagnetic polymer microballoon. Nanometer Fe3O4 grain prepared in coprecipitation process has its surface coated with oleophilic layer to form hydrophobic Fe3O4 magnetic fluid, and the magnetic fluid is dissolved in hydrophobic olefin monomer and oil soluble initiator via stirring to form homogeneous dispersive oil phase fluid. The oil phase fluid is crushed and dispersed into homogeneous oil drops in a spouting suspension polymerization process so as to form homogeneous O / W suspension in water phase. Under certain polymerizing temperature, oil drop is cured fast and constant temperature polymerized into homogeneous size superparamagnetic polymer microballoon. The superparamagnetic polymer microballoon has size of about 10 micron, specific saturation magnetic intensity of 15-20 emu / g, homogeneous magnetic content, stable chemical property and latent application in biological separation.

The invention relates to wide-temperature-range low-loss Mn-Zn ferrite specially used for a solar energy inverter, and a preparation method thereof. The Mn-Zn ferrite comprises main components of: 53.5mol%-54.5mol% of iron oxide calculated according to Fe2O3, 8.0mol%-10.0mol% of zinc oxide calculated according to ZnO, and balance of mangano-manganic oxide. The Mn-Zn ferrite also comprises minor components of, by weight: 0.03-0.04% of CaCO3, 0.005-0.01% of Nb2O5, 0.01-0.03% of V2O5, and 0.03-0.2% of Co2O3, calculated according to standard substances of CaCO3, Nb2O5, V2O5, and Co2O3. The Mn-Zn ferrite is prepared with an oxide method, and is sintered under an elevator furnace densification condition. The obtained product has relatively high initial magnetic permeability mui, and low power loss Pcv. With the Mn-Zn ferrite, the loss under a high-frequency transformer operation status is reduced, and the efficiency of the transformer is improved. With the Mn-Zn ferrite, miniature inverterscan be produced with high frequency, small size, and intelligence. Also, a requirement of efficiency improving under a condition of illumination variation can be satisfied. The product is advantaged in high reliability and good stability. With the product, a miniature inverter can be used in environments with large temperature variations, such as deserts and islands.

A preparation method of Fe3O4@PEG@SiO2 artificial antibody for detecting thifensulfuron methyl comprises modifying the surface of Fe3O4 magnetic nanoparticles with polyethylene glycol 2000, coating the surface with SiO2 shell layer to form a core-shell-shell structure, diluting marker molecules in the SiO2 shell layer to form specific recognition site holes complementary with marker molecular structure, size and functionality so as to arrive at molecular selective recognition and detection for target analyses. The preparation method of the artificial antibody comprises the steps of first, preparing Fe3O4 magnetic nanoparticles, and modifying their surface with polyethylene glycol; second, adding the target molecule thifensulfuron methyl, a crosslinking agent and a catalyst, and hydrolyzing to obtain Fe3O4@PEG@SiO2 particles with surface-marked thifensulfuron methyl; third, diluting template molecule with a mixed solution of acetic acid and acetone having a volume ratio of 1:4 to obtain the Fe3O4@PEG@SiO2 artificial antibody with selective recognition marker molecules, the antibody having maximum saturated binding capacity of 41.28 mg / g for thifensulfuron methyl, the absorption rate reaches 0.45 mg / g.min within first 30 min which is 5.34 times and 3.46 times that of a non-marking method.

The invention relates to a magnetic solid acid catalyst which comprises magnetic aluminum oxide and transitional metal loaded on the magnetic aluminum oxide, wherein the weight proportion of the magnetic aluminum oxide and the transitional metal is 1.5-99:1 on the basis of transitional metal sulphate, and the transitional metal is one or more selected from IB, IIB, IVB and VIII groups; the magnetic aluminum oxide comprises Gamma-Al2O3 and magnetic particles embedded in the Gamma-Al2O3, and the weight proportion of the Gamma-Al2O3 and the magnetic particles is 1-9:1; the magnetic particles comprise SiO2 and magnetic kernels embedded in the SiO2, and the weight proportion of the SiO2 and the magnetic kernels is 0.1-1:1; the magnetic kernel is one or more selected from magnetic metals, magnetic alloys and magnetic metal oxides. The magnetic solid acid catalyst has the characteristics of large specific surface area, good magnetic property, stable physicochemical property, and the like, can be applied to processes of fluidized bed and magnetic stabilization bed and is specially suitable for integrating with a magnetic stabilization bed reactor for acid catalyzed reaction in the filed of oil processing.

A thin film magnet and a cylindrical ferromagnetic thin film having a high maximum energy product (greater than 120 kJ / m3) and thus suitable for use in miniature high performance devices are provided. The thin film magnet is produced by means of physical vapor deposition. The thin film magnet is an (Nd1-xRx)yM1-y-zBz alloy having a ferromagnetic compound of the Nd2Fe14B type as its main phase, wherein R is Tb, Ho, and Dy and M is Fe metal or an Fe-based alloy including at least one of Co and Ni, 0.04< / =x< / =0.10,0.11< / =y< / =0.15, and 0.08< / =z< / =0.15. A perpendicular magnetization film having such a composition is deposited on the side wall of a substrate in the columnar (or cylindrical) form thereby obtaining a cylindrical ferromagnetic thin film having radial anisotropy.

Embodiments disclosed herein include methods of modifying synthetic garnets used in RF applications to reduce or eliminate Yttrium or other rare earth metals in the garnets without adversely affecting the magnetic properties of the material. Some embodiments include substituting Bismuth for some of the Yttrium on the dodecahedral sites and introducing one or more high valency ions to the octahedral and tetrahedral sites. Calcium may also be added to the dodecahedral sites for valency compensation induced by the high valency ions, which could effectively displace all or most of the Yttrium (Y) in microwave device garnets. The modified synthetic garnets with substituted Yttrium (Y) can be used in various microwave magnetic devices such as circulators, isolators and resonators.

A composite, soft-magnetic powder comprising soft-magnetic, iron-based core particles having an average particle size of 2-100 μm, and boron nitride-based coating layers each covering at least part of each soft-magnetic, iron-based core particle, said coating layers being polycrystalline layers comprising fine boron nitride crystal grains having different crystal orientations and an average crystal grain size of 3-15 nm, the average thickness of said polycrystalline layers being 6.6% or less of the average particle size of said soft-magnetic, iron-based core particles, is produced by (1) mixing iron nitride powder having an average particle size of 2-100 μm with boron powder having an average particle size of 0.1-10 μm, (2) heat-treating the resultant mixed powder at a temperature of 600-850° C. in a nitrogen atmosphere, and (3) removing non-magnetic components.

A high speed magnetic data writer containing a stitched pole tip that works in conjunction with the main pole is disclosed, together with a process for their manufacture. The material composition of each of these two sub-structures is slightly different; one sub-structure is optimized for high magnetic damping while the other sub-structure is optimized for high saturation magnetization.