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Biomass-derived Carbon Compounds and their Potential Application for Electronic and Magnetic Materials
Published in Paweł K. Zarzycki, Pure and Functionalized Carbon Based Nanomaterials, 2020
Retno Asih, Malik Anjelh Baqiya, Yoyok Cahyono, Darminto
The rGO prepared from coconut shells shows an increase in the magnetization with the increase of defect concentration tuned by heating temperature during thermal-reduction process. A weak but appreciable magnetic hysteresis was confirmed in all samples—rGO-400, rGO-600, rGO-800, and rGO-1000 (Darminto et al. 2018). The saturation magnetization (MS) increases with increasing heating temperature, as does the remanence magnetization (Mr) and coercivity (HC). A significant enhancement of MS was achieved when rGO was thermally reduced at 1000°C, i.e., rGO-1000 (Darminto et al. 2018).
Electronic Structure and Properties
Published in Alan Cottrell, An Introduction to Metallurgy, 2019
We have of course so far been considering conditions at low temperatures, where the system seeks the state of lowest internal energy. Experiment shows that the saturation magnetization of a ferromagnetic substance decreases at higher temperatures, becoming zero at the Curie point Tc(780, 1075, 365°C, respectively, for Fe, Co, Ni). Above this temperature the substance is paramagnetic.
Electromagnetic Principles of Switched Reluctance Machines
Published in Berker Bilgin, James Weisheng Jiang, Ali Emadi, Switched Reluctance Motor Drives, 2019
Equation (2.80) has important conclusions for better understanding the torque production principles in an SRM. It says that in an inductor with an air gap, most of the energy is stored in the air gap itself, which is a high-reluctance magnetic path as compared to the core. As it will be discussed in the next section, in a switched reluctance machine, the energy stored in the air gap is converted to mechanical energy. The permeability of ferromagnetic materials reduces as the level of saturation increases. This means that when the core saturates, its permeability reduces, the reluctance of the magnetic path increases, and the magnetic system can store more energy, which is then converted to mechanical energy. Therefore, the torque production capability of an SRM improves as the saturation level of the core increases.
Synthesis and characterization of manganese ferrite nanostructure by co-precipitation, sol-gel, and hydrothermal methods
Published in Particulate Science and Technology, 2019
Leila Asadi Kafshgari, Mohsen Ghorbani, Asghar Azizi
The multi-walled MnFe2O4 hollow nanosheets is clearly visible in Figure 2b for hydrothermal samples. Further, from Figure 2c, some MnFe2O4 exhibit a reticular structure, and they form a large agglomerate cluster (sol-gel samples). This is due to presence of strong interaction among magnetic particles, such as van der Waals force and magnetic dipolar interaction (Wang et al. 2015). Also, this can be attributed to the generation of large volume of gases during the combustion reaction which occurs in a very short time (Pandav et al. 2016). In fact, the coercivity, the saturation magnetization, and the field required for the saturation depends strongly on the particle size which, in turn, is a function of the heat-treatment temperature and consequently influences the magnetic exchange interaction (Kronmuller and Fahnle 2003; Herzer 2005). Saturation magnetization values are high for small nanoparticles and this can be attributed to the high crystallinity of the particles as considered in Table 1. Whereas, magnetization reduces with decreasing the particle size especially for the particles with very small size due to the prominent surface effects (Maaz et al. 2009; Pal and Chauhan 2010; Iranmanesh et al. 2017).
Green synthesis and investigations of structural, cation distribution, morphological, and magnetic properties of nanoscale nickel ferrites: the effect of green fuel proportion
Published in Phase Transitions, 2021
Govind D. Kulkarni, Mangesh V. Khedkar, Sandeep B. Somvanshi, Ravikumar M. Borade, S. D. More, K. M. Jadhav
The magnetic properties were studied by the vibrating sample magnetometer technique with a magnetic field of 15 kOe. The typical hysteresis curve recorded for all the samples is shown in Figure 4. Figure 4 shows that initially, with the increase in the magnetic field, magnetization increases. Furthermore, the increase in the magnetic field increases the saturation magnetization, but attains a saturation value. The values of saturation magnetization (MS) measured from this plot are presented in Table 7. Also, the values of coercivity (HC), remanence magnetization (Mr), and remanence ratio (Mr/MS) recorded from M-H plots are listed in Table 7.
Efficiency enhancement for indirect vector-controlled induction motor drive
Published in International Journal of Electronics, 2019
Mini Sreejeth, Madhusudan Singh, Parmod Kumar
Magnetic saturation reduces self-inductance up to 80% of its nominal value (Krishnan, 2015). The effect of magnetic saturation is analysed for 3 hp IM drive for light-load rated speed of operation. As the efficiency improvement is most prominent during light-load operations, the results are tabulated for 20% and 40% of rated load for operation at rated speed condition for the 3-hp IM drive and are given in Table 5. A decrease in efficiency of 0.9% and 1.3% at 40% and 20% of rated load condition, respectively, is observed with efficiency enhancement control due to saturation effect. For similar conditions, a decrease in efficiency of 1.8% and 5% is observed with conventional control method.