scholarly journals Calculating Curie temperatures for rare-earth permanent magnets: Ab initio inspection of localized magnetic moments in d -electron ferromagnetism

2020 ◽  
Vol 101 (14) ◽  
Author(s):  
Munehisa Matsumoto ◽  
Hisazumi Akai
Keyword(s):  
Rare Earth ◽  
Ab Initio ◽  
Permanent Magnets ◽  
Magnetic Moments ◽  
Curie Temperatures

Microstructure and Magnetic Properties of RE2.28Fe13.58B1.14 Alloys

2016 ◽  
Vol 848 ◽  
pp. 709-714 ◽  
Author(s):  
Gang Fu ◽  
Jiang Wang ◽  
Mao Hua Rong ◽  
Guang Hui Rao ◽  
Huai Ying Zhou
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Rare Earth ◽  
Single Phase ◽  
Permanent Magnets ◽  
Industrial Applications ◽  
Arc Melting ◽  
Light Rare Earth Elements ◽  
Curie Temperatures ◽  
Microstructure And Magnetic Properties

The rare-earth (RE) permanent magnets based on Nd2Fe14B with excellent magnetic properties have been widely used in industrial applications. In this work, the crystal structure, microstructure and magnetic properties of Nd2.28Fe13.58B1.14, Ce2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys prepared by arc-melting were investigated. The results show that all alloys are single phase with tetragonal Nd2Fe14B-type (space group P42/mnm). The Curie temperatures (Tc) of RE2.28Fe13.58B1.14 (RE=Nd, Ce, Pr) alloys are 583 K, 423 K and 557 K, respectively. On the other hand, the coercivities of Nd2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys are about 1.05 T and 1.23 T, respectively, while that of Ce2.28Fe13.58B1.14 alloy is only about 0.25 T due to the poor squareness of hysteresis loop. Meanwhile, the saturation magnetizations of Nd2.28Fe13.58B1.14 and Pr2.28Fe13.58B1.14 alloys are about 135 emu/g and 113 emu/g, respectively, while that of Ce2.28Fe13.58B1.14 alloy is about 97 emu/g. It was indicated that the Curie temperatures and magnetic properties of RE2.28Fe13.58B1.14 alloys with the same crystal structure are dependent on light rare earth elements.

scholarly journals Relevance of 4f-3d exchange to finite-temperature magnetism of rare-earth permanent magnets: An ab-initio-based spin model approach for NdFe12N

2016 ◽  
Vol 119 (21) ◽  
pp. 213901 ◽  
Author(s):  
Munehisa Matsumoto ◽  
Hisazumi Akai ◽  
Yosuke Harashima ◽  
Shotaro Doi ◽  
Takashi Miyake
Keyword(s):  
Rare Earth ◽  
Ab Initio ◽  
Finite Temperature ◽  
Permanent Magnets ◽  
Spin Model ◽  
Model Approach

scholarly journals Magnetic structure analysis of rare earth permanent magnet Sm2Fe17N3

2014 ◽  
Vol 70 (a1) ◽  
pp. C1460-C1460 ◽  
Author(s):  
Kotaro Saito ◽  
Nobuhito Inami ◽  
Yasuo Takeichi ◽  
Tetsuro Ueno ◽  
Ryoko Sagayama ◽  
...  
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Structure Analysis ◽  
Permanent Magnets ◽  
Nearest Neighbor ◽  
Magnetic Moments ◽  
High Coercivity ◽  
Diffraction Measurement ◽  
Fe Sites

Rare earth intermetallic compound Sm2Fe17N3 exhibits notalble magnetic properties such as high Curie temperature and high coercivity which are very suitable for permanent magnets [1,2]. Although microscopic magnetic structure is one of the basic information for magnetic materials, there is no report about the magnetic structure of Sm2Fe17N3 for our knowledge. This is because samarium's neutron absorption cross section is huge enough to make researchers hesitate to have neutron diffraction experiments of Sm compounds. We have carried out powder neutron diffraction measurement of Sm2Fe17N3 with a straightforward solution to the problem by taking long measurement time. Synchrotron x-ray diffraction measurements with single crystal has also been done to obtain initial crystal structure parameters for magnetic structure analysis and we have succeeded to analyze the magnetic structure of Sm2Fe17N3 at room temperature. Among four Fe sites in the unit cell, while one Fe site which is the nearest neighbor of nitrogen shows smaller magnetic moment than normal iron, two Fe sites show enhancement in their magnetic moments. This phenomenon can be understood as 'cobaltization' of Fe by the adjacent nitrogen through hybridization.

Magnetic properties of rare earth chromium borates at high temperatures

2021 ◽  
pp. 166-170
Author(s):  
O.K. Kuvandikov ◽  
◽  
N.I. Leonyuk ◽  
V.V. Malsev ◽  
M.M. Kuzmin ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Temperature Dependence ◽  
High Temperatures ◽  
Wide Temperature Range ◽  
Magnetic Moments ◽  
Chemical Formula ◽  
Temperature Range ◽  
Curie Temperatures

Temperature dependence of the magnetic susceptibility has been studied for rare-earth borates NdCr3(BO3)4, SmCr3(BO3)4 and LuCr3(BO3)4 by the Faradey method in the wide temperature range (300-1200 K). The dependence for each phase follows the Curi - Weis law. The Curie temperatures, Neel temperatures and magnetic moments corresponding to the chemical formula of the crystals, have been found.

scholarly journals Ab initio study of magnetic and structural properties of Fe-Ga alloys

2018 ◽  
Vol 185 ◽  
pp. 04013 ◽  
Author(s):  
Mariya Matyunina ◽  
Mikhail Zagrebin ◽  
Vladimir Sokolovskiy ◽  
Vasiliy Buchelnikov
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Ab Initio ◽  
Local Density ◽  
Magnetic Moments ◽  
Coupling Constants ◽  
First Principles Calculations ◽  
Exchange Correlation ◽  
Heisenberg Hamiltonian ◽  
Curie Temperatures

The structural and magnetic properties for a series of Fe100-xGax alloys (x = 18 – 30 at.%) are studied in the framework of first-principles calculations and Monte Carlo simulations. The both, general gradient approximation and local density approximation are considered for the exchange-correlation functional. The ground state ab initio calculations are performed for both D03 and L12 crystal structures. It is shown that for general gradient approximation, the optimized lattice parameters and total magnetic moments are found in the better agreement with experimental ones. Using the calculated exchange coupling constants for studied compositions, Curie temperatures are estimated by means of Monte Carlo simulations of Heisenberg Hamiltonian.

Photonic Applications of Rare-Earth-Doped Materials

MRS Bulletin ◽  
1999 ◽  
Vol 24 (9) ◽  
pp. 16-20 ◽  
Author(s):  
Andrew J. Steckl ◽  
John M. Zavada
Keyword(s):  
World War Ii ◽  
Rare Earth ◽  
Atomic Number ◽  
Permanent Magnets ◽  
Magnetic Moments ◽  
Energy Levels ◽  
Electronic Energy ◽  
Characteristic Energy ◽  
History Of ◽  
Re Elements

The elements of the lanthanide series, from Ce (atomic number 58) to Yb (atomic number 70), form a group of chemically similar elements that have in common a partially filled 4f shell. These so-called “rare earth” (RE) elements usually take on a 3+ ionic state (RE3+). Because the 4f electronic-energy levels of each lanthanide ion are shielded from external fields by 5s2 and 5p6 outer-shell electrons, RE3+ energy levels are predominantly independent of their surroundings.The characteristic energy levels of 4f electrons of the trivalent RE elements have been investigated in detail by Gerhard Heinrich Dieke and co-workers and were reported approximately 30 years ago. The Dieke diagram showing RE3+ energy levels is a familiar tool of scientists and engineers working with RE elements. However, the history of RE elements goes back to the year 1787 in the small Swedish town of Ytterby near Stockholm and to the gifted amateur mineralogist and military man Lt. Carl Axel Arrhenius. Arrhenius discovered an unusual black mineral in Ytterby (perceived initially as much rarer in occurrence and in concentration than the common ores or earths of aluminum, calcium, etc.). Many new elements were discovered by various chemists upon analysis of this black stone and others like it. The names given to these elements are variations of the location where the first discovery was made: yttrium, ytterbium, terbium, and erbium. The history of RE elements is fascinating and involves many other famous names in science: Berzelius, Gadolin, Bunsen.The properties of these elements and their multifaceted applications to science and industry are equally fascinating and have remained important to this day. Commercial applications of RE elements began after World War II, when their available quantity and purity were greatly enhanced by improved separation techniques developed as a part of the Manhattan Project. Until fairly recently, the main industrial application of RE elements has been in permanent magnets. The unpaired 4f electrons result in some RE elements having the highest magnetic moments of any element. The development and applications of RE magnets are reviewed in a very interesting article by Livingston3 in a previous MRS Bulletin issue. In this issue of MRS Bulletin, we have taken as our aim to review some of the properties and applications of RE elements relevant to photonics.

L10 rare-earth-free permanent magnets: The effects of twinning versus dislocations in Mn-Al magnets

2020 ◽  
Vol 4 (9) ◽  
Author(s):  
Yuxiao Jia ◽  
Yuye Wu ◽  
Shuang Zhao ◽  
Shulan Zuo ◽  
Konstantin P. Skokov ◽  
...  
Keyword(s):  
Rare Earth ◽  
Permanent Magnets

scholarly journals Special Issue: Advances in Computational Electromagnetics

2021 ◽  
Vol 7 (6) ◽  
pp. 89
Author(s):  
Valerio De Santis
Keyword(s):  
Rare Earth ◽  
Magnetic Materials ◽  
Permanent Magnets ◽  
Computational Electromagnetics ◽  
Superconducting Materials ◽  
Special Issue ◽  
Full Characterization ◽  
Recent Advances

Recent advances in computational electromagnetics (CEMs) have made the full characterization of complex magnetic materials possible, such as superconducting materials, composite or nanomaterials, rare-earth free permanent magnets, etc [...]

scholarly journals Design of External Rotor Ferrite-Assisted Synchronous Reluctance Motor for High Power Density

2021 ◽  
Vol 11 (7) ◽  
pp. 3102
Author(s):  
Md. Zakirul Islam ◽  
Seungdeog Choi ◽  
Malik E. Elbuluk ◽  
Sai Sudheer Reddy Bonthu ◽  
Akm Arafat ◽  
...  
Keyword(s):  
Rare Earth ◽  
Permanent Magnets ◽  
Design Procedure ◽  
Lumped Parameter Model ◽  
High Power Density ◽  
Analytical Design ◽  
Synchronous Reluctance Motor ◽  
Lumped Parameter ◽  
Reluctance Motor ◽  
External Rotor

The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea.

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