Method for improving the performance of praseodymium cobalt (prcos) permanent magnet systems

Abstract

The application discloses a method for predicting the performance of a doped PrCo5 praseodymium-cobalt permanent magnet system, constructs a plurality of structural system models of the doped PrCo5 praseodymium-cobalt permanent magnet system, performs prediction calculation on the structural system models based on quantum chemistry calculation software, determines a doped system capable of improving the performance of the doped PrCo5 praseodymium-cobalt permanent magnet system, and further determines the optimal solution of the plurality of structural system models in terms of the magnetic performance. The application provides a method for predicting the performance of a doped PrCo5 praseodymium-cobalt permanent magnet system, constructs a plurality of structures of the doped praseodymium-cobalt permanent magnet, and performs calculation on the structural models by using software, so as to determine the advantages and disadvantages of the doped models in terms of the improvement of the magnetic performance by judging the magnetic moment intensity of each model, and further obtain an optimal doped model capable of improving the performance, thereby effectively reducing the processes of testing, trial production and inspection, and improving the efficiency of product development.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of magnetic material preparation and performance prediction. More particularly, the present application relates to a method for predicting the performance of a doped PrCo5 praseodymium-cobalt permanent magnet system. BACKGROUND

[0002] Rare earth elements are a collective term for 17 special elements, which are named because Swedish scientists used rare earth compounds when extracting rare earth elements. Rare earth elements are a collective term for 17 chemical elements with atomic numbers 21, 39 and 57-71 in the periodic system group III B. There are 17 rare earth elements, namely scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

[0003] Research shows that permanent magnets are a major application scenario for rare earth elements. Of the 17 rare earth elements, elements used to manufacture permanent magnets include samarium, neodymium, praseodymium, terbium and dysprosium. Different rare earth elements are doped in permanent magnets to improve the coercive field strength of permanent magnets at high temperatures, the magnetic moment strength of permanent magnets, the saturation magnetization strength, etc. Different doping ratios of the same doping element (such as gadolinium replacing praseodymium in praseodymium-cobalt permanent magnets) have different effects on the performance of permanent magnets. In order to find the optimal doping system and parameters for improving the performance of doped PrCo5 praseodymium-cobalt permanent magnet systems, a large number of tests are often required, which has high time and economic costs. SUMMARY

[0004] An object of the present application is to solve at least the above problems and / or deficiencies and to provide at least the advantages described hereinafter.

[0005] To achieve these objects and other advantages and in view of the preambles, a method for predicting the performance of a doped PrCo5 praseodymium-cobalt permanent magnet system is provided. A plurality of structural system models of doped PrCo5 praseodymium-cobalt permanent magnets are constructed. Quantum chemistry calculation software is used to perform prediction calculations on the structural system models to determine a doping system that can improve the performance of the doped PrCo5 praseodymium-cobalt permanent magnet system, and then determine the optimal solution for improving the magnetic performance from the plurality of constructed structural system models.

[0006] Preferably, the quantum chemistry calculation software is configured to employ a first-principles quantum mechanics program CASTEP based on a density functional method;

[0007] The parameters for constructing the model using CASTEP are configured as follows:

[0008] The atomic radius of cobalt Co is 152 pm, and the electronic orbit of the cobalt atom participating in the calculation is 3d 7 , 4s 2 ,

[0009] The atomic radius of praseodymium Pr is 247 pm, and the electronic orbit of the praseodymium atom participating in the calculation is 4f 3 , 5s 2 , 5p 6 , 6s 2 The electronic orbit of the gadolinium atom participating in the calculation is 4f 7 , 5d 1 , 6s 2 The electronic orbit of the erbium atom participating in the calculation is 4f 12 , 6s 2 ;

[0010] The pseudopotential adopts the plane wave ultra-soft pseudopotential of CASTEP, the size of the plane wave pseudopotential Ecut is set to 420 eV, the maximum number of self-consistent calculation SCF steps is set to 1000, the number of convergence times is set to 1000, the energy / atom convergence threshold of SCF calculation is 0.5E-06 eV, and the thickness of the vacuum layer is Initial lattice parameters: α = β = 90°, γ = 120°;

[0011] The energy optimization algorithm adopts the quasi-Newton method BFGS, and the total energy convergence threshold is 0.5E-05 eV / atom;

[0012] The Brillouin zone k points are generated by the Monkhorst-Pack method, and the k point setting uses the highest precision K point setting (3x3x4);

[0013] The calculation type adopts the geometry optimization of CASTEP, and the GGA+U functional is used for comparative analysis in the calculation of geometry optimization and electronic properties.

[0014] Preferably, the construction process of the structure system model is configured to include:

[0015] Step one, using CASTEP to construct a praseodymium-cobalt PrCo5 permanent magnet solid surface model and different unit cell surface models, and performing calculation based on the density functional theory to obtain the most stable system structure configuration;

[0016] Step two, in the architecture configuration, the same predetermined rare earth element is doped in different proportions or different predetermined rare earth elements are doped in the same proportion to construct a plurality of structure system models of doped PrCo5 praseodymium-cobalt permanent magnet.

[0017] Preferably, the prediction calculation process is configured to include:

[0018] Step three, based on the structure system models of different doping modes, corresponding unit cell models and low Miller index crystal surface models are constructed, and corresponding structure optimization is carried out by setting corresponding spin parameters to obtain corresponding magnetic performance indicators;

[0019] Step four, based on the comparison of each magnetic performance indicator, the magnetic moment strength corresponding to different doping parameters is obtained, and the structure system model with the strongest magnetic moment is preferentially selected to determine the doping system that can improve the magnetic performance.

[0020] Preferably, when the CASTEP is used to construct the unit cell model PrCo5, the unit cell parameters are as follows:

[0021] The lattice constant is Alpha = beta = 90 degrees, gamma = 120 degrees;

[0022] Since Pr is bonded to 18 Co atoms in the 18-coordinate geometry, and there are two non-equivalent co-sites, in the first Co site, Pro is bonded to three equivalent Pr and six equivalent Co atoms in the 9-coordinate geometry, and all cobalt-cobalt bond lengths are In the second co-site, Co is bonded to four equivalent Pr and eight Co atoms, forming a mixed CoPr CoPr4Co8 cubic octahedron of edge, corner and face sharing CoPr, and all cobalt-cobalt bond lengths are

[0023] Preferably, the magnetic performance indicators are configured to include:

[0024] Energy bands, state densities, and bond occupations that can reflect the basic properties of crystal surfaces;

[0025] Magnetic moment strength, saturation magnetization, HOMO, LUMO that can reflect the properties of the configuration system

[0026] The present application at least includes the following beneficial effects: the present application constructs a plurality of structures of doped praseodymium-cobalt permanent magnets, and uses software to calculate each structure model, judges the pros and cons of each doping model for improving magnetic performance through the magnetic moment strength of each model, and then obtains the optimal doping model for improving performance, effectively reducing the process of testing, trial production and testing, and improving the efficiency of product development.

[0027] Other advantages, objects, and features of the application will be apparent to those skilled in the art from the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A predicted flow principle block diagram of the application is shown in the figure;

[0029] Figure 2 A predicted flow schematic diagram of the application is shown in the figure;

[0030] Figure 3 A PrCo5 crystal cell schematic diagram of the Pr-Co permanent magnet constructed by the application is shown in the figure;

[0031] Figure 4 An optimization process curve schematic diagram of the structural parameter optimization of the application is shown in the figure;

[0032] Figure 5 A state density schematic diagram of the application after optimization is shown in the figure. DETAILED DESCRIPTION

[0033] The application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement the application according to the description.

[0034] The application constructs a Pr-Co permanent magnet doped structure, simulates through quantum chemistry calculation software, determines a doped system for improving the magnetic performance of the Pr-Co permanent magnet doped structure, and finds that the constructed model has good magnetic performance.

[0035] Specifically, as shown in the figure, Figures 1-2 The application provides a prediction method for improving the performance of a PrCo5 Pr-Co permanent magnet doped system, which comprises the following steps:

[0036] Constructing a PrCo5 Pr-Co permanent magnet solid surface model and different crystal cell surface models; performing density functional theory calculation to determine the most stable system structure configuration;

[0037] Constructing a gadolinium, erbium, and other heavy rare earth element doped configuration, doping a predetermined same rare earth element in different proportions or doping a predetermined different rare earth element in the same proportion in the system structure configuration, since the stability of the interstitial doped system is generally worse than that of the substitution doped system, the doped element of the application is gadolinium or erbium element by substitution doping instead of interstitial doping, and a plurality of PrCo5 Pr-Co permanent magnet doped structure system models are constructed;

[0038] Build different doping (doping element is gadolinium or erbium, doping ratio is set between 0% to 100%) configuration cell model, set the correct spin parameters (according to its ferromagnetic characteristics, set the ISPIN spin number of praseodymium atoms, gadolinium atoms, erbium atoms and cobalt atoms in the model, whether the spin direction is UP or DOWN, etc.), and carry out structure optimization (relaxation) respectively, calculate the basic properties such as energy band, state density, bond occupation and the properties of the system such as magnetic moment strength, saturation magnetization, HOMO, LUMO, etc. A plurality of structures of doped praseodymium cobalt permanent magnets are constructed, and each structure model is calculated by using software, the advantages and disadvantages of each doping model for improving the magnetic performance are judged by the magnetic moment strength of each model, and then the optimal doping element and / or doping ratio for improving the performance are obtained, and the prediction of the optimal doping system is completed.

[0039] The calculation software of the application adopts the CASTEP open source software package, and the model parameters are: the atomic radius (calculated) of cobalt (Co) is 152pm; the atomic radius (calculated) of praseodymium (Pr) is 247pm, the electron configuration of cobalt atom is: 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 , 3d 7 , 4s 2 , the electron configuration of praseodymium atom is: 1s 2 , 2s 2 , 2p 6 , 3s 2 , 3p 6 , 4s 2 , 3d 10 , 4p 6 , 5s 2 , 4d 10 , 5p 6 , 6s 2 , 4f 3 . Because in chemical reactions, generally only the valence electrons change, the inner electrons and the atomic nucleus are a relatively stable and unchanged entity, therefore, in the calculation, the inner electrons of the electron orbit of each atom are generally not involved in the calculation, in the calculation in this paper, the electron orbit of the cobalt atom involved in the calculation is 3d 7 , 4s 2 , the electron orbit of the praseodymium atom involved in the calculation is 4f 3 , 5s 2 , 5p 6 , 6s 2 , the electron orbit of the gadolinium (Ga) atom involved in the calculation is 4f 7 , 5d 1 , 6s 2 , and the electron orbit of the erbium (Er) atom involved in the calculation is 4f 12 , 6s2 .

[0040] The pseudopotential adopted is the CASTEP plane wave ultrasoft pseudopotential, and the energy optimization algorithm adopts the quasi-Newton method BFGS. The Brillouin zone k points are generated by the Monkhorst-Pack method. The calculation type adopts the geometric optimization of CASTEP, the exchange-correlation functional adopts the PBE functional (Perdew Burke Ernzerhof), the plane wave pseudopotential Ecut size is set to 420 eV, the maximum number of SCF steps is set to 1000, the energy / atom convergence threshold of SCF calculation is: 0.5E-06 eV, the optimization method adopts BFGS, and the total energy convergence threshold is: 0.5E-05 eV / atom. The initial lattice parameters are: α=β=90°, γ=120°. The k-point setting of our calculation uses the highest precision K-point setting (3x3x4). The convergence number of self-consistent calculation (SCF) is set to 1000 times, and the thickness of the vacuum slab is The LDA+U functional is used for comparative analysis in the geometry optimization (Geometry Optimization) and electronic property (Properties) calculation.

[0041] The crystal cell system PrCo5 established by calculation has the following crystal cell parameters:

[0042] α=β=90°, γ=120°;

[0043] Pr is bonded to 18 Co atoms in an 18-coordinate geometry. There are six short and twelve long (3.18197) Pr-Co bond lengths. There are two inequivalent co-sites. In the first Co site, Pro is bonded to three equivalent Pr and six equivalent Co atoms in a 9-coordinate geometry. All cobalt-cobalt bond lengths are In the second co-site, Co is bonded to four equivalent Pr and eight Co atoms, forming a mixture of edge, corner, and face-sharing CoPr CoPr4Co8 cuboctahedra. All cobalt-cobalt bond lengths are

[0044] Embodiment:

[0045] 1. The PrCo5 crystal cell diagram of the praseodymium-cobalt permanent magnet is established as shown in Figure 3 , wherein the white color is a praseodymium atom, and the black color is a cobalt atom;

[0046] 2. The established Pr-Co permanent magnet PrCo5 model is subjected to geometry optimization, the plane wave ultra-soft pseudo-potential of CASTEP is adopted, the energy optimization algorithm adopts quasi-Newton method BFGS, the Brillouin zone K point is set to (3x3x4). The calculation type adopts the geometry optimization of CASTEP, the exchange-correlation functional adopts PBE functional (Perdew Burke Ernzerhof), the plane wave pseudo-potential Ecut size is set to 420 eV, the maximum SCF step number is set to 1000, the energy / atom convergence threshold of SCF calculation is 0.5E-06 eV, the optimization method adopts BFGS, and the total energy convergence threshold is 0.5E-05 eV / atom. Initial lattice parameters: α=β=90°, γ=120°. The convergence number of self-consistent calculation (SCF) is set to 1000 times, and the vacuum slab thickness is all taken The electronic orbital parameters of cobalt (Co) atoms used in the calculation are: 3d7 4s2, and the electronic orbital parameters of praseodymium atoms (Pr) are: 4f3 5s2 5p6 6s2

[0047] The geometry optimization optimization process curve is as shown in Figure 4 The atomic bond populations (Mulliken) after optimization are as shown in Table 1-2:

[0048] Table 1

[0049] Species Ion s p d f Total Charge(e) Co 1 0.80 0.79 7.69 0.00 9.29 -0.29 Co 2 0.80 0.79 7.70 0.00 9.29 -0.29 Co 3 0.76 0.86 7.69 0.00 9.31 -0.31 Co 4 0.76 0.86 7.69 0.00 9.31 -0.31 Co 5 0.76 0.86 7.69 0.00 9.31 -0.31 Pr 1 2.52 4.35 2.28 2.35 11.49 1.51

[0050] Table 2

[0051] Bond Population Length(A) Co 1--Co 4 0.49 2.41866 Co 2--Co 5 0.49 2.41866 Co 2--Co 3 0.49 2.41867 Co 1--Co 3 0.49 2.41867 Co 2--Co 4 0.49 2.41867 Co 1--Co 5 0.49 2.41868 Co 3--Co 4 0.65 2.43162 Co 4--Co 5 0.66 2.43162 Co 3--Co 5 0.66 2.43165 Co 2--Pr 1 -1.60 2.80778 Co 1--Pr 1 -1.60 2.80778 Co 1--Co 2 1.39 2.80780

[0052] It can be seen that the overall bond population of the optimized structure is larger, the Co-Co bond is relatively small, and the state density diagram result is as shown in Figure 5

[0053] 3. The unit cell after optimization is subjected to site doping with gadolinium and erbium elements, and the doping ratio is set to 5%;

[0054] 4. The gadolinium doped and erbium doped models established above are optimized;

[0055] 5. The gadolinium doped and erbium doped models after optimization are subjected to magnetic moment strength and saturation magnetization calculation;

[0056] ​6. Obtain the SpinDensity values ​​for gadolinium doping and 10% erbium doping from the calculation results, respectively: SD_GA_5 and SD_Er_5;

[0057] 7. Using the larger doping models in SD_GA_5 and SD_Er_5 obtained in the previous step as crystal plane models that can improve magnetic performance, calculate the performance of systems with 10%, 15%, ..., 95% doping in step size of 5%. This method can effectively verify the performance improvement of multiple models designed in the research, obtain the optimal solution among several schemes, and effectively shorten the research and development cycle.

[0058] The above solution is merely an illustration of a preferred example and is not limited thereto. When implementing this invention, appropriate substitutions and / or modifications can be made according to the user's needs.

[0059] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0060] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A method of improving the prediction of the properties of doped PrCo5 praseodymium-cobalt permanent magnet systems, characterized in that, The structural system model of the plurality of doped PrCo5 praseodymium-cobalt permanent magnet is constructed, and a prediction calculation is performed on the structural system model based on quantum chemistry calculation software to determine a doping system capable of improving the performance of the doped PrCo5 praseodymium-cobalt permanent magnet system, and then an optimal solution with improved magnetic performance in the plurality of constructed structural system models is determined; The construction process of the structural system model is configured to include: Step one, constructing a PrCo5 praseodymium-cobalt permanent magnet solid surface model and different cell surface models by using CASTEP, and performing calculation based on density functional theory to obtain the most stable system structure configuration; Step two, doping a predetermined same rare earth element at different proportions or doping a predetermined different rare earth element at the same proportion in the system structure configuration to construct a plurality of structural system models of doped PrCo5 praseodymium-cobalt permanent magnets; The prediction calculation process is configured to include: Step three, constructing a corresponding cell model and a low Miller index crystal surface model based on the structural system model of different doping methods, and performing corresponding structure optimization by setting corresponding spin parameters to obtain corresponding magnetic performance indicators; Step four, comparing each magnetic performance indicator to obtain the magnetic moment strength corresponding to different doping parameters, and optimally selecting the structural system model with the strongest magnetic moment to determine the doping system capable of improving the magnetic performance.

2. The method of claim 1, wherein the PrCo5 praseodymium-cobalt permanent magnet system is doped with at least one of Dy, Tb, Ho, Er, Tm, Yb, Lu, and Gd. The quantum chemistry calculation software is configured to use the ab initio quantum mechanics program CASTEP based on the density functional method; The parameter configuration for constructing the model by using CASTEP includes: The atomic radius of cobalt Co is 152 pm, the electron orbitals of the cobalt atoms involved in the calculation are 3d 7 , 4s 2 , The atomic radius of Pr is 247 pm, the electron orbitals of the Pr atoms involved in the calculation are 4f 3 , 5s 2 , 5p 6 , 6s 2 The atomic radius of Gd is 198 pm, the electron orbitals of the Gd atoms involved in the calculation are 4f 7 , 5d 1 , 6s 2 The atomic radius of Er is 179 pm, the electron orbitals of the Er atoms involved in the calculation are 4f 12 , 6s 2 ; The pseudopotential uses the plane wave ultra-soft pseudopotential of CASTEP, the plane wave pseudopotential Ecut size is set to 420 eV, the maximum number of self-consistent calculation SCF steps is set to 1000, the convergence number is set to 1000 times, the energy / atom convergence threshold of SCF calculation is 0.5E-06 eV, the vacuum layer thickness is 20 Å, the initial lattice parameters are a=4.97 Å, b=4.97 Å, c=3.97 Å, α=β=90°, and γ=120°; The energy optimization algorithm uses the quasi-Newton method BFGS, and the total energy convergence threshold is 0.5E-05 eV / atom; The k points in the Brillouin zone are generated by the Monkhorst-Pack method, and the K point setting uses the highest precision K point setting (3x3x4); The calculation type uses the geometry optimization of CASTEP, and the GGA+U functional is used for comparative analysis in the geometry optimization and electronic property calculation.

3. The method of claim 1, wherein the PrCo5 praseodymium-cobalt permanent magnet system is doped with at least one of Dy, Tb, Ho, Er, Tm, Yb, Lu, and Gd. When the cell model PrCo5 is constructed by using CASTEP, the cell parameters are as follows: The lattice constants are a=b=5.040698 Å, c=3.940062 Å, α=β=90°, and γ=120°; Because Pr is bonded to 18 Co atoms in 18-coordinate geometry, and there are two nonequivalent co-sites, in the first Co site, Pro is bonded to three equivalent Pr and six equivalent Co atoms in 9-coordinate geometry, and all cobalt-cobalt bond lengths are 2.45 Å; in the second co-site, Co is bonded to four equivalent Pr and eight Co atoms, forming a mixed edge, corner, and face-sharing CoPr CoPr4Co8 cuboctahedron, and all cobalt-cobalt bond lengths are 2.48 Å.

4. The method of claim 1, wherein the PrCo5 praseodymium-cobalt permanent magnet system is doped with at least one of Dy, Tb, Ho, Er, Tm, Yb, Lu, and Gd. The magnetic performance index is configured to include: energy bands, state density, bond occupancy that can reflect the basic properties of the crystal face; magnetic moment strength, saturation magnetization, HOMO, LUMO that can reflect the properties of the configuration system.

Images