74results about How to "Improve the magnetocaloric effect" patented technology

A magnetocaloric effect heterostructure having a core layer of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, and a constricting material layer coated on at least one surface of the magnetocaloric material core layer. The constricting material layer may enhance the magnetocaloric effect by restriction of volume changes of the core layer during application of a magnetic field to the heterostructure. A magnetocaloric effect heterostructure powder comprising a plurality of core particles of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, wherein each of the core particles is encapsulated within a coating of a constricting material is also disclosed. A method for enhancing the magnetocaloric effect within a giant magnetocaloric material including the step of coating a surface of the magnetocaloric material with a constricting material is disclosed.

The magnetic composite material of the present invention is used as a working substance in the magnetic refrigeration system and comprising at least two phases, including, a first phase composed of an intermetallic compound represented by a general formula: La(Fe(Co, Ni)Si)₁₃, having an NaZn₁₃ type crystal structure, and a second phase is composed of an iron alloy containing Si. The first phase is precipitated in an expansion size of 100 μm or less in average. Preferably, the magnetic composite material contains Fe as a principal component, La in an amount from 4 atomic % to 12 atomic %, Si in an amount from 2 atomic % to 21 atomic %, and Co and Ni in a total amount from 0 atomic % to 11 atomic %, and the total amount of Fe, Co and Ni being from 75 atomic % to 92 atomic %.

The invention discloses a high-throughput preparation method for a LaFeSi-based magnetic refrigeration material. According to the method, in the process of casting an alloy ingot from material melt, awedged copper mold is adopted, so the cooling rate of the melt along the height direction is in gradient change, the wedged alloy ingot with a solidified alloy structure gradient is obtained; and annealing is then carried out, and the magnetothermal effect of the obtained LaFeSi-based blocky magnetic refrigeration material with a NaZn13 structure has a gradient. Preferably, by utilizing microstructures obtained by a scanning electron microscope characterizing different cooling rates in the same sample at high throughput, in combination with a magnetothermal performance test, a corresponding relation between different structures, magnetothermal effect and copper mold width is obtained, which can be used for rapidly screening needed sample preparation parameters and the like.

The invention discloses a magnetic phase change alloy. The magnetic phase change alloy has a formula of (Mn1-alpha M alpha)xNiy(Ge1-beta Si beta)z; M=Fe or Co; x is not more than 36 and not less than 30; y is not more than 36 and not less than 30; z is not more than 36 and not less than 30; x+y+z=100; alpha is more than 0 and less than 0.8; and beta is not more than 1 and not less than 0. The magnetic phase change alloy has high-temperature huge magnetic heat effect, and widens the temperature range of a magnetic heating material; needed raw materials are rich in storage, easy to store and low in cost; and a preparation process is simple and reliable, is excellent in stability, and is easy to industrial produce. The magnetic phase change alloy is excellent in comprehensive performance, and is an ideal Mn base non-rare earth magnetic heat pump and thermomagnetic power generation candidate material.

The invention discloses a lanthanum-iron-silicon/gadolinium composite magnetic refrigeration material and a preparation technology thereof and belongs to the field of magnetic refrigeration materialsin magnetic functional materials. A La-Fe-Si/Gd composite magnetic refrigeration material with high strength and high performance is obtained by adopting metal Gd particles as a second magnetic refrigeration material of playing a bonding role and La-Fe-Si series alloy through hot pressing sintering. The invention further discloses a preparation method and application of the La-Fe-Si/Gd composite magnetic refrigeration material. The La-Fe-Si series alloy and Gd are magnetic refrigeration materials with excellent performance, so that the mechanical properties are complementary. Through additionof Gd elemental particles, the mechanical property of the La-Fe-Si series alloy is greatly strengthened, and furthermore, the damage to the magnetic refrigeration performance caused by use of other binders is avoided. The obtained magnet has good magnetic refrigeration performance and relatively high strength, is simple in equipment, simple in operation and relatively low in cost in an implementation process, is high in economic value and has important application significance in the field of magnetic refrigeration, and mass production is easy to implement.

The invention discloses a rare-earth-based high-entropy amorphous alloy material high in magnetocaloric effect. The molecular formula of the rare-earth-based high-entropy amorphous alloy is GdaCobAlcYdMe, wherein a, b, c, d and e represent the atom percentage content of the corresponding element, a is larger than or equal to 24.8 and smaller than or equal to 25, b is larger than or equal to 8 andsmaller than or equal to 25.4, c is larger than or equal to 24.8 and smaller than or equal to 25.4, d is larger than or equal to 5 and smaller than or equal to 15, e is larger than or equal to 10 andsmaller than or equal to 20, a+b+c+d+e is equal to 100, and M is one of Dy, Er and Ho. On the basis of a GdCoAly high-entropy amorphous alloy, M is used for replacing Y, the high-entropy amorphous alloy high in magnetocaloric effect is obtained, the alloy is stable in magnetocaloric performance, the magnetic variation temperature range is wide, and elements likely to volatile or oxidize are not included. In addition, the completely amorphous structure of the high-entropy amorphous alloy needs no crystallization heat treatment, the preparation process is simple, and the high-entropy amorphous alloy material has good magnetocaloric performance and has good application prospects in the technical field of magnetic refrigeration.

The invention relates to gadolinium borate and a preparation method and application thereof. According to preparation of gadolinium borate, Gd<3+> is used as a raw material, and small molecular weight BO3<3-> is used as a ligand. The preparation method comprises the following steps: placing gadolinium oxide and boric acid into a quartz porcelain boat, grinding solids into powders, uniformly mixing, drying, transferring the quartz porcelain boat into a quartz tube furnace, heating to 400 DEG C and keeping the temperature for 10 h, heating to 1000 DEG C and keeping the temperature for 6h, cooling to room temperature to obtain a white powdery solid, washing and carrying out suction filtration, and drying to obtain gadolinium borate. The gadolinium borate which is white powdery crystal can be applied in preparation of magnetic refrigeration materials. Synthetic equipment is simple, and the preparation method is fast and easy to operate. The gadolinium borate is a borate compound and has very strong stability and good heat stability from a strong acid environment to a strong base environment. By raising mass ratio of rare earth to the ligand, magnetic density is raised, and magnetic refrigeration effect of the material is greatly enhanced.

The invention relates to hydrogen fluoride gadolinium oxide as well as a preparation method and application thereof. The gadolinium oxyfluoride has the following general formula: Gd (OH) yF3-y, wherein y is equal to 0.5-2.5.

The invention relates to an application of a coordination compound in low temperature magnetic refrigeration. The coordination compound is two-water two (glycolic acid) and manganese (II). The invention belongs to the technical field of manganese application. The application of coordination compound in low temperature magnetic refrigeration aims to provide a magnetic refrigeration working substance with a high refrigeration effect in a low temperature area. The temperature range of the two-water two (glycolic acid) and manganese (II) is 0.3K-40K. The magnetic field exerted in the magnetization stage when the coordination compound is used is 1T-7T. The two-water two (glycolic acid) and manganese (II) of 1kg is magnetized with isothermality when the temperature is 1.7K in the optimized implementation scheme. Obtained magnetic entropy change is 61.2J/K when the magnetic field exerted outside is 7T.

The invention belongs to the field of magnetic materials and relates to a material capable of regulating and controlling magnetism and related magnetic effects through bending or twisting, a preparation method of the material and application of the material. The chemical formula of the material is Ni50-aCoaMn35-bFebXc, wherein a is larger than or equal to 12 and smaller than or equal to 17, b is larger than or equal to 0 and smaller than or equal to 10, c is larger than or equal to 5 and smaller than or equal to 20, and X comprises Sn, Ga, In, Si, Ge, Ti, Zr, Hf, V, Nb and Ta. The preparationmethod of the material comprises the following steps of: carrying out electric arc melting on high-purity raw materials to obtain a NiMi-based alloy block; and carrying out melt rapid quenching on theblock under vacuum to obtain a phase-change thin strip material. According to a method for regulating and controlling magnetism by applying isostatic pressure in the prior, the effect of the method is single, the controllability of the method is poor, the pressure applying mode of the method is complex, and the application of the method is limited. With the preparation method of the invention adopted, the above problems in the prior art can be solved; the obtained phase-change alloy thin strip can show large magnetic regulation and control and large magnetocaloric effects near the room temperature, can be effectively applied to a magnetic refrigeration process, and can achieve strain output through bending or twisting; and therefore, the magnetism and related magnetic effects of the phase-change alloy thin strip are regulated and controlled, and the application prospect of the phase-change alloy thin strip is effectively expanded.

The invention belongs to the field of magnetic refrigeration, and particularly relates to a temperature-graded magnetic heating material and a preparation method thereof. The temperature-graded magnetic heating material comprises a Ni50Mn37Sn13 alloy film layer and a Ni50Mn35In15 alloy film layer. The phase change temperature of the Ni50Mn37Sn13 alloy film layer ranges from 295 K to 305 K. The phase change temperature of the Ni50Mn35In15 alloy film layer ranges from 301 K to 310 K. The thickness ratio of the Ni50Mn37Sn13 alloy film layer to the Ni50Mn35In15 alloy film layer is 1:3 to 3:1. According to the temperature-graded magnetic heating material and the preparation method thereof, by carrying out gradient design and preparation on the magnetic heating material, the work temperature zone of an existing magnetic heating material can be expanded, and the magnetic heating effect of the material can be improved; and a design rule and a regulating and control mechanism of the magnetic heating material are set up, and the gradient magnetic heating temperature material is pushed to develop towards application.

The invention discloses tetrahydroxy gadolinium oxide dihydrate and preparation and applications thereof and relates to hydroxyl coordinate rare earth gadolinium materials. The tetrahydroxy gadolinium oxide dihydrate belongs to an orthorhombic system and a space group Cmcm and the molecular formula is Gd2O(OH)4(H2O)2. Cell parameters a is equal to 16.5835, b is equal to 12.9747, c is equal to 7.3106 and V is equal to 1573.05. During preparation, gadolinium nitrate hexahydrate, sodium formate and glycine are dissolved in water, the above is transferred to a reaction still after the pH (Potential Of Hydrogen) is adjusted through ammonium hydroxide, the temperature is risen to 160 degrees and the temperature keeps consistent, then the temperature is reduced to the room temperature, and the tetrahydroxy gadolinium oxide dihydrate which is colorless acicular crystal is obtained after filtering and washing. The tetrahydroxy gadolinium oxide dihydrate can be applied to preparation of magnetic refrigeration materials.

The invention provides a multi-ferric composite material having both magnetic refrigeration effect, electrically-controlled magnetic effect and magnetic memory effect nearby the room temperature, anda preparation method and application thereof. The multi-ferric composite material comprises a ferroelectric PMN-PT monocrystalline substrate, and a La-Fe-Co-Si ferromagnetic alloy layer with giant magneto-caloric effect, wherein metal electrodes are evaporated on two surfaces of the PMN-PT monocrystalline substrate, and two surfaces are adhered with the La-Fe-Co-Si ferromagnetic alloy layer through adhesive so as to form the multi-ferric composite material. The advantage of the multi-ferric composite material is that the considerable electrically controlled magnetic effect is provided nearby the room temperature, and the magnetic memory effect induced by the pulse voltage is represented. And meanwhile, since the ferromagnetic layer of the structure has giant magneto-caloric effect, a new model for overcoming the heating of the storage unit by using the magnetic refrigeration is provided. The multi-ferric composite material provided by the invention has important and actual significancefor developing a novel multifunctional composite device having both the magnetic refrigeration effect and the magnetic memory effect.

The invention relates to a manganese cobalt germanium-based alloy room temperature magnetic refrigeration material and a preparation method thereof. The general chemical formula of the room temperature magnetic refrigeration material is Mn1-xZrxCoGe, wherein x is larger than or equal to 0.04 and is less than or equal to 0.06. The preparation method comprises the following steps of weighing manganese pieces, cobalt pieces and germanium blocks according to the molar ratio of each element in the general chemical formula, and smelting into alloy ingots; and annealing the smelted alloy ingots undervacuum condition (the vacuum degree is less than or equal to 10-2Pa) at the annealing temperature of 1123-1273K, preserving heat for 75-100 hours, and quenching to room temperature after heat preservation. The Mn atoms in MnCoGe mother alloy is replaced by Zr atoms, so that ferromagnetic phase transition and martensitic structure phase transition which are originally separated are coupled near room temperature, and the room temperature magnetic refrigeration material obtains an excellent magnetic thermal performance and is expected to be applied in the field of room temperature magnetic refrigeration.

The invention discloses fluorinated gadolinium carbonate as well as a preparation method and application thereof and belongs to rare earth gadolinium materials. The fluorinated gadolinium carbonate is a novel fluorine and carbonate coordinated rare earth gadolinium material, and the structural composition formula of the fluorinated gadolinium carbonate is [GdCO3F] n (1), the maximum magnetic entropy change value of the material is 69.9 J kg <-1 > K <-1 > at 2K and 7T. The preparation method comprises the following steps of: adding hydrated gadolinium carbonate as a raw material into water; adding sodium tetrafluoroborate; fully stirring an obtained mixed solution, and transferring the solution into a hydrothermal kettle for hydrothermal reaction; and performing washing and drying to obtain a target product. A synthesis device of the fluorinated gadolinium carbonate is simple, preparation is convenient and fast, operation is easy, and the fluorinated gadolinium carbonate can be applied to preparation of magnetic refrigeration materials. Rare earth Gd < 3 + > with a high spinning ground state and small magnetic anisotropy is selected as cations, CO3 < 2-> with small molecular weight is selected as a ligand, the mass ratio of the rare earth to the ligand is increased to improve the magnetic density, and meanwhile, a fluorine ligand is doped into the material, so that the magnetic refrigeration effect of the material is greatly improved.

The invention discloses an adhesion La (Fe, Si)<13> bulk-shaped magnet with excellent heat-conducting property and a preparation method therefor, and belongs to the technical field of a functional material. A LaFe<11.5>Si<1.5>H<1.65> magnet is prepared by taking LaFe<11.5>Si<1.5>H<1.65> magnetic powder as a magnetic material, taking sodium silicate as a main binder, and taking high-temperature-resistant epoxy resin as an auxiliary binder. The strength of the obtained magnet is greatly improved while the prepared magnet has excellent heat-conducting property. By adoption of the adhesion La (Fe, Si)<13> bulk-shaped magnet with the excellent heat-conducting property and the preparation method therefor, the obtained magnet has high magnetothermal effect, relatively high strength, and simple equipment in an implementation process, simple and convenient operation, relatively low cost, easy realization of large-scale production, high economic value, and high application prospect in the magnetic cooling field.