22 results about "Magnetic phase transition" patented technology

The invention belongs to the technical field of magnetic refrigeration, and particularly discloses a rare earth europium-based zirconate magnetic refrigeration material and a preparation method and application thereof. The general chemical formula of the rare earth europium-based zirconate magnetic refrigeration material is (Eu1-xMx) (Zr1-yNy) O3, M is any one of Ca, Sr or Ba, N is any one of Nb, Ta, Ti or Hf, x is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 0.5, and the magnetic phase transition temperature of the rare earth europium-based zirconate magnetic refrigeration material is less than 10K. The magnetic refrigeration material shows excellent magnetocaloric performance near the liquid helium temperature, and is expected to be applied to the liquid helium temperature zone magnetic refrigeration technology; and the preparation method is simple in process, safe and environment-friendly, and can be applied to industrial production.

The invention belongs to the technical field of magnetic refrigeration materials, and particularly relates to manganese pentaethylenehexamine hydrochloride and a preparation method and extremely low temperature magnetic refrigeration application thereof. The chemical formula of the extremely low temperature magnetic refrigeration material is [Mn (C10H28N6)] Cl2; the magnetic phase transition temperature of the extremely-low-temperature magnetic refrigeration material is lower than 0.4 K. The extremely-low-temperature magnetic refrigeration material has a large magnetothermal effect near 1K, and when the magnetic field change is 0-5T, the maximum magnetic entropy change is smaller than or equal to 40.8 J * kg <-1 > * K <-1 >. The extremely-low-temperature magnetic refrigeration material is rich in preparation raw materials, simple in process, free of rare earth elements, low in cost and suitable for industrial large-scale production.

The present invention is a hydrogenated alloy represented by the compositional formula RE(M1-xAx)yXzHw, wherein x, y, z, and w respectively satisfy 0.08≤x≤0.13, 12.3≤y≤13.2, 0.005≤z≤0.25, and 0<w<Hsat (where Hsat represents the amount of saturated hydrogen at ordinary temperature), RE is one or more elements selected from rare earth elements and Zr and must include La, M is one or more elements selected from Fe, Co, Mn, Ni, Nb, W, Ta, Cr, Cu, Ag, and Ti and must include Fe, A is one or more elements selected from Si, Al, Ga, P, Ge, Sn, and In and must include Si, and X is one or more elements selected from B, C, and N and must include B. According to the present invention, a hydrogenated alloy with suppressed splitting can be provided in which the magnetic phase transition temperature (Tc) is controlled by the amount of hydrogen while maintaining performance.

The invention belongs to the technical field of condensed state physics and material research, and particularly relates to a heavy rare earth transition metal oxide magnetocaloric material screening method which comprises the following steps: obtaining zero field cooling of a test sample and a magnetization intensity-temperature curve of the field cooling, and deriving the magnetization intensity-temperature curve of the field cooling to obtain a magnetic field temperature curve of the field cooling; then the absolute value of the derivative of the field cooling magnetization intensity-temperature curve is obtained, and an absolute value curve is obtained; calculating an average magnetic phase transition temperature based on the absolute value curve; calculating the variance of the absolute value curve at the average magnetic phase transition temperature; calculating the dimensionless variance of the absolute value curve based on the variance of the absolute value curve at the average magnetic phase transition temperature; obtaining an isothermal magnetization curve of the test sample and calculating a magnetic entropy change value; and based on the dimensionless variance value, establishing a quantitative relationship between the magnetic phase change interaction intensity and the magnetic entropy change value, and further screening out a target sample. And theoretical support is provided for development and physical mechanism analysis of the low-temperature heavy rare earth based giant magnetocaloric material.

Disclosed herein are magnetocaloric materials comprising alloys useful for magnetic refrigeration applications. The disclosed alloys include Dysprosium, Erbium, Holmium, Yttrium, or Terbium, and Cerium, Neodymium, and / or Gadolinium components that are fairly inexpensive. In certain embodiments, the materials exhibit second-order magnetic phase transitions near their Curie temperatures with negligible thermal and structural hysteresis losses, making them attractive for magnetic refrigeration. Surprisingly, the performance of the disclosed materials is comparable to or better than that of other expensive, rare-earth-based magnetocaloric materials.

The application provides a self-supporting magnetic phase change material manganese arsenic film and a preparation method and application thereof, and relates to the technical field of magnetic functional materials. The self-supporting magnetic phase change material manganese arsenic film is a manganese arsenic film with a polycrystalline structure. The preparation method comprises the following steps: depositing a water-soluble sacrificial layer on the surface of a magnesium oxide single crystal substrate by a pulsed laser deposition method; depositing a manganese arsenic film with a polycrystalline structure on the surface of the sacrificial layer by a magnetron sputtering method; dissolving the water-soluble sacrificial layer to make the manganese arsenic film peel off to form a self-supporting film, and then transferring the self-supporting film to the surface of a new magnesium oxide single crystal substrate to obtain the transferred self-supporting magnetic phase change material manganese arsenic film. The application solves the problem that phase transition temperature drift or magnetic performance attenuation easily occurs in the film peeling and transferring process, and realizes controllable peeling and transferring of a large-area and high-quality film under the premise of ensuring the stoichiometric ratio stability and the integrity of the crystal structure.

The application belongs to the technical field of magnetic phase change materials, and particularly relates to a method for improving the physical performance of a Bi-rich phase Mn2Sb-based alloy material, which comprises the following steps: mixing a parent phase alloy with a diffusion source, sintering, and diffusing the diffusion source into the parent phase alloy to obtain a Bi-rich phase Mn2Sb-based alloy material; the diffusion source accounts for 2.9% to 30% of the total mass of the parent phase alloy and the diffusion source; the diffusion source is Dy 100‑y Cu y , 5<=y<=40 or Pr 100‑z Ga z , 5<=z<=40; the parent phase alloy is (Mn2Sb) 1‑x Bi x , 0 The application diffuses rare earth alloy to the grain boundary phase of the Bi-rich phase Mn2Sb-based alloy to optimize the magnetic performance of the material, so that the material can be widely applied to magnetic memories, magnetic drivers, magnetic sensors, thermomagnetic electric conversion devices, solid-state refrigeration devices and the like.

This invention discloses a method for achieving phase transitions between different topological magnetic structures based on magnetic heterojunction materials. This method involves finding two-dimensional magnetic material systems capable of realizing magnetic skyrmions or magnetic bismallens; calculating in detail the magnetic parameters of the material system through first-principles calculations, including Heisenberg exchange coupling, Dzyaloshinskii-Moriya (DM) interaction, and magnetic anisotropy; and realizing stable magnetic skyrmions or magnetic bismallens under various competing magnetic interactions based on atomic-level micromagnetic simulations. By applying voltages in different directions to the ferroelectric substrate, the overall polarization state is changed, thereby altering the magnitude and direction of magnetocrystalline anisotropy, thus achieving the mutual conversion between magnetic skyrmions and magnetic bismallens. Compared to traditional current or magnetic field manipulation methods, this invention, by controlling the topological magnetic phase transition through voltage, avoids Joule heating, thus facilitating the realization of lower power consumption topological magnetic track memories.

The invention belongs to the technical field of magnetic refrigeration materials, and particularly discloses a potassium europium phosphate extremely-low-temperature magnetic refrigeration material and a preparation method and application thereof. The material KEuPO4 belongs to an orthorhombic system, and the space group is Pnma; the polycrystalline block of the material can be prepared by adopting a step-by-step solid-phase reaction method in a hydrogen-argon mixed gas atmosphere. The magnetic phase change temperature of the material ranges from 1.0 K to 1.2 K along with the reversible giant magnetocaloric effect, under the magnetic field changes of 0-2 T and 0-5 T, the maximum isothermal magnetic entropy change values of the material range from 32.8 J / kg.K to 33.4 J / kg.K and 49.7 J / kg.K to 52.1 J / kg.K respectively, and the maximum isothermal magnetic entropy change values of the material are both superior to those of a commercial extremely-low-temperature magnetic refrigeration material Gd3Ga5O12. The europium-based phosphate KEuPO4 material provided by the invention has the advantages of simple preparation process, good material stability, remarkable magnetocaloric effect and the like, and has a relatively good application prospect in the field of extremely low-temperature magnetic refrigeration.

The application discloses a high-efficiency heat transfer copper pipe with magnetic control phase change and a preparation process thereof, and relates to the technical field of heat exchange devices.The copper pipe comprises a copper pipe base body and a magnetic phase change composite slurry.The application utilizes a gradient magnetic field to dynamically control slurry filling, and through an axial / radial gradient magnetic field, the directional migration of magnetic nano-particles is guided, so that the high-heat-conducting particle concentration at the inlet end of the copper pipe is significantly higher than that at the outlet end.A magnetic force difference generated by the gradient magnetic field is utilized to drive the magnetic particles to gather in the direction of increasing magnetic field intensity, so as to form a functional gradient structure matched with the heat flow distribution.The structure enables the inlet end to quickly absorb and concentrate heat flow, and through the heat conduction network between the particles, heat is efficiently transferred to the outlet end, so that a self-adapting heat flow distribution mechanism is formed in the heat transfer process of the whole copper pipe, and the heat transfer capacity and heat load demand of different regions are accurately matched.

The application belongs to the technical field of new materials, and particularly relates to a Laves phase composite material for thermomagnetic power generation and a preparation and application thereof. 0.9 R 0.1 Fe2, wherein R is Ta and / or Nb, so that the material has a magnetic phase transition characteristic at room temperature, and tetragonal phase In is introduced to form a two-phase composite material, wherein the Hf 0.9 R 0.1 Fe2 phase has ferromagnetism at room temperature, and the tetragonal phase In provides excellent thermal conductivity, and through adjustment of the two-phase components, the excellent thermomagnetic power generation Laves phase composite material is obtained. The Laves phase composite material for thermomagnetic power generation prepared by the application constructs a heterostructure of room-temperature ferromagnetism / high thermal conductivity, the preparation process is simple, and the excellent induced voltage value is realized through a two-step method, and the series of materials are expected to be used in the field of thermomagnetic power generation.

The invention belongs to the technical field of photonic crystal display, and discloses a heat-assisted magnetic recording-erasing photonic crystal film which is composed of a flexible polymer matrix and a magnetic phase change photonic crystal embedded in the flexible polymer matrix. The magnetic phase-change photonic crystal comprises superparamagnetic nanoparticles and a magnetic color-fixing phase-change material, and the magnetic color-fixing phase-change material is a sorbitan fatty acid ester phase-change material or a polyoxyethylene ether phase-change material. In the crystal film, the flexible polymer matrix plays roles in flexible self-supporting, protecting and limiting the flowing of the magnetic phase-change photonic crystal, and the magnetic phase-change photonic crystal is combined, so that the obtained photonic crystal film is endowed with magnetic writing-stable display-erasing functions under a heat-assisted condition, and has the advantages of repeated writing, low-energy-consumption color display and the like; a new thought can be provided for preparation of display devices which are low in energy consumption and can be repeatedly used; the preparation method is simple, convenient to operate and suitable for popularization and application.

The application discloses a kind of power generation method and device using impact energy, utilize isotropic pressure change to drive the magnetic phase change of pressure-sensitive magnetic composite material, make its magnetic flux density change;The pressure-sensitive magnetic composite material includes magnetic intermetallic compound Mn-Co-Si-Ge and solid-state pressure conduction medium.The application uses solid-state pressure conduction medium, and converts impact force in uniaxial direction into isotropic pressure change, so there is no special requirement for the mechanical strength of Mn-Co-Si-Ge alloy particles, with the advantage of strong bearing capacity;And the Mn-Co-Si-Ge alloy used is transition intermetallic compound, and the material cost is lower.

The invention discloses a magnetic refrigeration material, a preparation method thereof and application of the magnetic refrigeration material in magnetic refrigeration in an extremely low temperature region. The chemical formula of the magnetic refrigeration material is Gd5 (C3N3O3) (OH) 12, the magnetic refrigeration material belongs to a hexagonal system, the space group is # imgabs 0 #, the cell parameter is # imgabs 1 #, the magnetic refrigeration material has relatively high magnetization intensity and a high-thermal-stability magnetic structure, and still shows superparamagnetic characteristics without magnetic phase change at extremely low temperature, and when the temperature T of the material is 2K and the applied magnetic field delta H is 7T, the maximum magnetic entropy change-delta Sm is 58.1 J * kg <-1 > * K <-1 >, and the maximum magnetic entropy change-delta Sm is 58.1 J * kg <-1 > * K <-1 >. The material is an ideal magnetic refrigeration material in an extremely low temperature region.

This invention belongs to the field of photonic crystal display technology and discloses a heat-assisted magnetic recording-erasing photonic crystal film. It consists of a flexible polymer matrix and a magnetic phase-change photonic crystal embedded therein. The magnetic phase-change photonic crystal comprises superparamagnetic nanoparticles and a magneto-solid-color phase-change material, wherein the magneto-solid-color phase-change material is a sorbitan fatty acid ester-based phase-change material or a polyoxyethylene ether-based phase-change material. In the crystal film of this invention, the flexible polymer matrix plays a role in flexible self-support and protection, and restricts the flow of the magnetic phase-change photonic crystal. Combined with the magnetic phase-change photonic crystal, the resulting photonic crystal film is endowed with magnetic writing-stable display-erasing functions under heat-assisted conditions, possessing advantages such as repeated writing and low-energy color display. This provides a new approach for the fabrication of low-energy, reusable display devices. Furthermore, the fabrication method involved is relatively simple, easy to operate, and suitable for widespread application.

This invention provides a layered quantum magnetic material and its preparation method. The method includes: (a) preparing a negative electrode; (b) preparing a positive electrode; (c) placing the positive and negative electrodes in a solution containing macromolecules; and (d) applying an electric current to the positive and negative electrodes at a predetermined temperature for a predetermined time to intercalate macromolecules into a quasi-two-dimensional layered quantum magnetic compound, thereby obtaining a layered quantum magnetic material intercalated with macromolecules. The quasi-two-dimensional layered quantum magnetic compound includes a transition metal phosphorus trichalcogenide, and the macromolecules include at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate and diethylmethyl-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide. According to the method for preparing layered quantum magnetic materials of this invention, by applying a voltage to insert macromolecules into the interlayer of the layered quantum magnetic material, the lattice parameters in the c-direction of the layered quantum magnetic material are effectively increased, and the magnetic phase transition temperature is successfully reduced.

The invention discloses a magnetic control phase change efficient heat transfer copper pipe and a preparation process thereof, and relates to the technical field of heat exchange devices.The copper pipe comprises a copper pipe base body and magnetic phase change composite slurry, slurry filling is dynamically regulated and controlled through a gradient magnetic field, and magnetic nanoparticles are guided to directionally migrate through an axial / radial gradient magnetic field; the concentration of high-thermal-conductivity particles at the inlet end of the copper pipe is remarkably higher than that at the outlet end of the copper pipe, magnetic force difference generated by magnetic field gradient is used for driving magnetic particles to gather in the magnetic field intensity increasing direction, and a functional gradient structure matched with heat flow distribution is formed. Heat is efficiently transferred to the outlet end through a heat conduction network among particles, so that the whole copper pipe forms a self-adaptive heat flow distribution mechanism in the heat transfer process, and it is ensured that the heat transfer capacity of different areas is accurately matched with the heat load requirement.

This invention discloses a solid-state functional device and system based on the first-order magnetic phase transition step effect, belonging to the field of energy converter technology. It solves the technical problems of large phase transition hysteresis losses and poor cycle controllability in existing solutions. The device includes a magnetic phase transition functional unit and a signal interaction unit. The magnetic phase transition functional unit is made of a material with first-order magnetic phase transition characteristics, which are manifested as a step-like abrupt change in the macroscopic magnetization intensity of the material near the phase transition point under external excitation. This invention breaks through the traditional energy pumping approach that relies on continuous changes in physical properties and external parameter resonance, achieving high instantaneous power density power output, ultra-high sensitivity physical quantity sensing, or precision micro-actuation. The achievable magnetic flux change rate is orders of magnitude higher than traditional solutions, thereby greatly improving the instantaneous power density and sensing response sensitivity of the system.

The invention provides europium-based halogenated phosphate as well as a preparation method and application thereof. The general structural formula of the europium-based halogenated phosphate is Eu5 (PO4) 3X, wherein X is halogen. The europium-based halogenated phosphate is prepared through a simple solid-phase reaction, the high-purity europium-based halogenated phosphate can be prepared through the dosage of raw materials, a specific sintering process and secondary tabletting, the unit cell space structure can be optimized, the stability of the europium-based halogenated phosphate is further improved, and the europium-based halogenated phosphate has large magnetic entropy change. The magnetic phase transition temperature of the prepared europium-based halogenated phosphate is smaller than 1K, the maximum magnetic entropy change under the magnetic field change of 0-5T is larger than or equal to 60 J.kg <-1 >. K <-1 >, the europium-based halogenated phosphate is an extremely-low-temperature region magnetic refrigeration material with excellent performance, scientific and technological progress in the fields of low-temperature physics, deep space exploration, aerospace and the like in China can be promoted, and the europium-based halogenated phosphate can be widely applied to the fields of low-temperature physics, deep space exploration, aerospace and the like. And high value-added utilization of rare earth resources can be promoted.

The present invention relates to a temperature-controlled concrete and a preparation method thereof based on magnetic field regulation of phase-change lightweight aggregate distribution. The components of the concrete are arranged in a mass ratio of (kg / m 3 : 730-870g magnetic phase-change lightweight aggregate; 240-380g shale sand; 450-550g cement; 40-60g silica fume; 0-30g fly ash; 5-7g water reducer; 0-61.4g daptom beads; 0-15g nano-SiO2; 50-80g water; 1.5-7.5g carbon fiber. Preparation method: 1. Design a magnetic field device to cover the entire concrete pouring area; 2. Mix the six magnetic phase-change aggregates; 3. Pre-wet the shale sand until saturated and dry; 4. Mix the silica fume, cement, fly ash, daptom beads, and nano-SiO2 uniformly; 5. Add the remaining components in two batches; 6. After mixing the concrete, pour it into a mold and activate the magnetic field device simultaneously; 8. After the concrete has initially set, turn off the magnetic field device and allow it to cure.

The utility model discloses a kind of battery pack and energy storage system with it, battery pack includes: battery shell, the inside surface of the battery shell is configured with magnetic piece;Battery module, the battery module is installed in the battery shell;Heating film unit, the heating film unit is set to the surface of the battery module, the surface of the heating film unit is connected with the magnetic piece position opposite magnetic phase change material piece;Wherein, the magnetic phase change material piece is spaced from the magnetic piece each other when not generating magnetic force, the magnetic phase change material piece generates magnetic force and is attracted to each other with the magnetic piece when reaching preset temperature, to drive the heating film unit road to separate from the battery module. According to the battery pack of the utility model embodiment, with high safety, lower cost and the like advantages.

This invention belongs to the field of magnetic refrigeration materials technology, specifically relating to manganese pentaethylenehexamine hydrochloride, its preparation method, and its application in ultra-low temperature magnetic refrigeration. The chemical formula of the ultra-low temperature magnetic refrigeration material is [Mn(C 10 H 28 [N6)]Cl2; the magnetic phase transition temperature of the ultra-low temperature magnetic refrigeration material is below 0.4K. The ultra-low temperature magnetic refrigeration material of this invention exhibits a large magnetocaloric effect near 1K, and the maximum magnetic entropy change is ≤40.8 J·kg when the magnetic field changes from 0 to 5T. ‑1 ·K ‑1 The aforementioned ultra-low temperature magnetic refrigeration material has abundant raw materials, a simple process, does not contain rare earth elements, is low-cost, and is suitable for industrial-scale production.