Hysteresis properties of magnetite and their dependence on particle size: A test of pseudo-single-domain remanence models

1986 ◽  
Vol 91 (B9) ◽  
pp. 9569 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Particle Size ◽  
Single Domain ◽  
Hysteresis Properties

scholarly journals The effects of different particle size Y2Ba4CuBiOy nanoparticles doped on the properties of single domain YBCO bulk superconductors by TSIG process

2012 ◽  
Vol 61 (19) ◽  
pp. 196102
Author(s):  
Wang Miao ◽  
Yang Wan-Min ◽  
Zhang Xiao-Ju ◽  
Tang Yan-Ni ◽  
Wang Gao-Feng
Keyword(s):  
Particle Size ◽  
Single Domain ◽  
Ybco Bulk ◽  
Bulk Superconductors

scholarly journals Effect of Mechanical Milling on the Magnetic Properties of SrFe12O19

2015 ◽  
Vol 12 (1) ◽  
pp. 28-30
Author(s):  
I Bsoul
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Crystallite Size ◽  
Mechanical Milling ◽  
Single Phase ◽  
Strontium Ferrite ◽  
Single Domain ◽  
Single Domain Particle ◽  
Ferrite Sample

In this work, a single phase strontium ferrite sample was mechanically milled for 60 h. It has been found that the crystallite size reduced by 85%. A dramatic drop (from 4500 to 1600 Oe) in the coercive filed was also observed. The observed reduction in the coercivity was attributed to the reduction of the single domain particle size.

Enhancing the coercivity of SmCo5 magnet through particle size control

2020 ◽  
Vol 8 (6) ◽  
pp. 2109-2116 ◽  
Author(s):  
Hao Tang ◽  
Mohammad Aref Hasen Mamakhel ◽  
Mogens Christensen
Keyword(s):  
Particle Size ◽  
Size Control ◽  
Domain Size ◽  
Single Domain ◽  
Bottom Up ◽  
Particle Size Control

The bottom-up synthesis of SmCo5 particles with stable single-domain size exhibit a maximum coercivity of 2.6 MA m−1 (33.1 kOe).

Shape Anisotropy as Coercivity Mechanism

2016 ◽  
Vol 869 ◽  
pp. 591-595 ◽  
Author(s):  
Marcos Flavio de Campos
Keyword(s):  
Particle Size ◽  
Domain Size ◽  
Magnetic Interaction ◽  
Shape Anisotropy ◽  
Easy Magnetization Axis ◽  
Single Domain ◽  
Ferromagnetic Phase ◽  
Easy Magnetization ◽  
Magnetization Axis ◽  
Coercivity Mechanism

The Alnico magnets (also called Ticonal) have coercivity attributed to shape anisotropy. The conditions for appearing this type of anisotropy are discussed, and the principal is the existence of elongated grains parallel to the easy magnetization axis. A very important detail is that the conditions assumed in the Stoner Wohlfarth model have to be obeyed. The assumptions are i) ferromagnetic phase with single domain particle size and ii) grains without magnetic interaction between them, magnetically insulated by a grain boundary paramagnetic phase. In Alnico magnets, the coercivity mechanism is coherent rotation of single domain size particles.

Squareness of NdFeB Stoner-Wohlfarth Hysteresis

2014 ◽  
Vol 802 ◽  
pp. 601-606
Author(s):  
Marcos Flavio de Campos ◽  
Fernanda A.S. da Silva ◽  
José Adilson de Castro
Keyword(s):  
Particle Size ◽  
General Result ◽  
Anisotropy Constant ◽  
Single Domain ◽  
Single Domain Particle ◽  
Hysteresis Curves ◽  
Intrinsic Coercivity ◽  
Grain Diameter

Hysteresis curves were calculated according the Stoner-Wohlfarth (SW) model using values of K2/K1from zero up to 0.25 (where K2is the 2ndorder anisotropy constant and where K1is the 1storder anisotropy constant). The SW calculations assume Nd2Fe14B nanocrystalline magnets with single domain particle size (grain diameter less than 150 nm). The effect of K2on several index of merit of magnets as BHmaxand squareness are discussed. As a general result, increasing K2, the intrinsic coercivity increases. However, the increase of K2almost does not improve the BHmaxof isotropic magnets. It is found that the effect of the K2/K1ratio is coupled with the effect of texture, i.e., the effect of K2is more significant for pronounced texture.

Application of Micromagnetic Models for Barium Ferrite Magnets

2015 ◽  
Vol 820 ◽  
pp. 199-204 ◽  
Author(s):  
Marcos Flavio de Campos ◽  
Fernanda A. Sampaio da Silva
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Coercive Force ◽  
Total Energy ◽  
Barium Ferrite ◽  
Magnetocrystalline Anisotropy ◽  
Single Domain ◽  
Square Root ◽  
Single Domain Particle ◽  
Magnetostatic Energy

The applicability of micromagnetics for phases with high magnetocrystalline anisotropy as barium ferrite Ba2Fe12O19and Nd2Fe14B is discussed. The Stoner-Wohlfarth model is very suitable for such phases, and also for PtFe and PtCo. It was discussed how to take into account the total energy of the system for grain size above the single domain particle size. For this situation of large grain size, the net magnetostatic energy of the system cannot be neglected. From energy considerations, it follows that the coercive force should decrease with the inverse of the square root of the grain size.

Hysteresis Modeling of NdFeB Magnets with High Nd

2016 ◽  
Vol 869 ◽  
pp. 585-590 ◽  
Author(s):  
Marcos Flavio de Campos ◽  
Fernanda A. Sampaio da Silva ◽  
José Adilson de Castro
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Boundaries ◽  
Paramagnetic Phase ◽  
Single Domain ◽  
Hysteresis Model ◽  
Ndfeb Magnets ◽  
Single Domain Particle ◽  
Hysteresis Curves ◽  
Hysteresis Modeling

The Stoner-Wohlfarth hysteresis model can describe very well the hysteresis curves since the assumptions of the model are compatible with the studied samples. These conditions are (i) single domain particle size and (ii) inexistence of interactions between the particles. These conditions are obtained in Nd2Fe14B magnets with nanocrystalline grain size below 200 nm and with high Nd, which promotes a paramagnetic phase at the grain boundaries. In the present study, both isotropic and anisotropic NdFeB magnets are modeled.

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