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near theoretical ultra-high magnetic performance of rare-earth nanomagnets via the synergetic combination of calcium-reduction and chemoselective dissolution

by:Newland     2019-10-20
Rare Earth Permanent Magnet Materials with excellent magnetic properties are usually synthesized by many chemical methods with calcium thermal reduction.
However, there are still great challenges in removing the remaining reducing agents, by-products and trace impurities produced during the purification process, which are used as inhibition intermediates, resulting in loss of productivity and purity, decreased magnetic properties.
Still, one after
There has been no serious study of the heat reduction process of calcium.
Here we introduce a new method to synthesize highly pure sm-cobalt (Sm-Co)
Rare earth nano network with near theoretical super
High magnetic properties through continuous calcium
Assisted Reduction and chemical selective dissolution.
Chemical selective dissolution effects of various solution mixtures were evaluated by Sm-purity, surface microstructure and magnetic propertiesCo.
Therefore, the mixture of ammonium cl/methanol solution can only selectively rinse the impurities without damaging Sm-Co.
In addition, in the case of more than 95, the magnetic properties can be significantly improved with ammonium cl treatment.
5% MS of batch SmCo.
On the mechanism for strengthening the stage --
The purity and magnetic properties were fully clarified based on the analysis results and statistical thermodynamic parameters.
We further demonstrate the potential application of chemical selective dissolution in other intermetallic compound magnets.
In the past few decades,
Hard by magnetic-and soft-
Because the phase has excellent magnetic properties other than conventional magnetic compounds, in-depth research has been carried out in the permanent magnet industry.
Through theoretical research, Skomski and Coey demonstrate that the expected value of the maximum energy product of hard/soft-is as high as 120 MG Oe.
As an excellent hard magnet, NdFeB produces a coupled composite magnet of about 56 MG Oe.
This excellent magnetic properties can be attributed to the unique interaction between the two distinct phases, called \"\".
Get hard/soft switch-
Coupled nano-composites, many manufacturing methods have been reported: one of the simplest chemical routes is the surface treatment of hard nano-materials such as soft-phase plating, sputtering, and the Ethox precursor method.
The genus of rare earth elements fund, including nd-iron-boron (Nd-Fe-B), samarium-cobalt (Sm-Co), and samarium-iron-nitride (Sm-Fe-N)
, Is expected to show the strongest exchange of experiments-
Coupling behavior due to its extremely high mandatory and energy product.
In magnetic hard material, Sm-Co (. , SmCo, SmCo)
Through a variety of chemical methods, such as sol-gel, co-
Precipitation, electro-spinning and electric deposition, followed by reduction-diffusion (R-D)process.
Recently, a study on the microstructure of control
Phased nano network with near Single
Domain size or high-
In order to further enhance the magnetic properties, features of the opposite sex are being developed.
A method for precisely controlling the diameter of magnetic structural fibers is the electrostatic spinning process.
When the fiber size is single
The domain size of a given magnet (. , SmCo: sub-micron-scale)
Can achieve the largest magnetic theory.
The reduction process is an integral step in all chemical methods for preparing rare earth magnets from oxides.
Because the rare earth element has a highly negative reduction potential (.
, Sm/S although the transition metal Co/C has traditionally used diluted acidic solutions and/or de-ionic water to rinse the remaining reducing agents.
However, it is inevitable that a by-product will be produced, resulting in poor magnetic properties of the resulting nano magnetic network.
With the release of a large amount of heat, the residue and water reacted strongly, and Ca/CaO formed water
An undissolved calcium compound that acts as a non-
Magnetic Products.
In addition, H gas is strongly generated to induce protons (H)
Formed in acidic solution, causing serious damage to the nano-net.
In the worst case, magnetic phase decomposition may occur.
So after the well
Controlled synthesis of nano-materials, presence of unwanted impurities and unsuccessful removal lead to poor magnetic properties and surface damage of hard magnetic nano-materials.
Surface defects further make it difficult to replace
Coupling interaction on hard-and soft-magnetic inter-phases.
However, most of the previously reported studies focused only on synthetic results, without covering the magnetic losses caused by by-products and the interaction between by-products and treated solutions.
What\'s interesting is Wang.
A new washing route is proposed (. Ethanol-water; two-step process)
For synthesis of Nd-Fe-
B nanoparticles with excellent magnetic properties;
However, they cannot deviate from the oxidation of the surface of the metallic magnetic phase and the formation of serious defects.
For our knowledge, there is no in-depth study to solve the R-that affects the surface properties of the chemoselective dissolution solution and the nano-scale magnetic structure of the magnetic energy-D process. Here, 1-
D. High purity sm-
Cobalt nano-structure with near theoretical super
High magnetic properties were synthesized by continuous electro-spinning, calcium thermal reduction and chemical selective dissolution.
Chemical selective effects of various conventional solutions were evaluated and fully discussed based on-
Rare earth magnetic SmCo nanoparticles and their magnetic properties and surface microstructure.
In addition, the applicability of the most effective selectivity
Dissolution solution of other rare earth magnetic phase (.
, SmCo and NdFeB systems)
In order to obtain high purity, excellent magnetic properties and to prove the further potential as a raw material applied to the exchange, discussions were also heldcoupled magnet.
A graphical summary of our experimental process can be found in the graph. .
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