scholarly journals Magnetics Hysteresis Properties and Microstructure of High-Energy (Nd,Dy)–Fe–B Magnets with Low Oxygen Content

2021 ◽  
Vol 122 (12) ◽  
pp. 1173-1182
Author(s):  
D. Yu. Vasilenko ◽  
A. V. Shitov ◽  
D. Yu. Bratushev ◽  
K. I. Podkorytov ◽  
V. S. Gaviko ◽  
...  
Keyword(s):  
Oxygen Content ◽  
Magnetic Hysteresis ◽  
Weight Fraction ◽  
Microscopy Study ◽  
High Energy ◽  
Maximum Energy ◽  
Triple Junctions ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Hysteresis Properties

Abstract Magnetic properties and microstructure of high-energy (Nd,Dy)–Fe–B magnets with Dy of no more than 1 wt % prepared via a low-oxygen routine are studied. Oxygen content in magnets does not exceed 0.20 wt %. 0.5 wt %–Dy addition reliably stabilizes the coercivity MHc higher than 13 kOe; in this case, the maximum energy density product (BH)max of magnets is 48.5–49.5 MG Oe. High magnetic hysteresis properties are gained via optimization of chemical and phase compositions of magnets, as well as their microstructure. The grain size of the main Nd2Fe14B phase is approximately 3.5 μm; and according to X-ray analysis, the weight fraction of additional Nd-rich phases (NdOx and Nd2O3) does not exceed 2.5%. Scanning electron microscopy study has demonstrated that in triple junctions of Nd2Fe14B grains there are two types of inclusions (В and С) of the NdOx phase, which significantly differ by their chemical composition. С-phase inclusions with low oxygen content (х ≈ 0.03) are enriched in Fe (40–50 wt %); whereas, В-phase with high oxygen content (х ≈ 0.70) contains 3–5 times less Fe. The angular dependences of coercivity of (Nd,Dy)–Fe–B magnets are presented.

The Difference between Iodine Number and Nitrogen Surface Area Determinations for Carbon Blacks

2006 ◽  
Vol 79 (1) ◽  
pp. 120-134 ◽  
Author(s):  
J. B. Donnet ◽  
A. Santini ◽  
D. Maafa ◽  
H. Balard ◽  
F. Padella ◽  
...  
Keyword(s):  
Iodine Number ◽  
Surface Area ◽  
Oxygen Content ◽  
Analytical Relationship ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Carbon Blacks ◽  
Elementary Analysis ◽  
Disordered Carbon ◽  
The Difference

Abstract The iodine number furnishes surface area values in disagreement with the NSA technique in the case of disordered carbon i.e., lower than NSA in case of high oxygen content (more than 2%), but higher for low oxygen content (less than 1%). Because carbon blacks are solids which exhibit graphitic structure, some milled graphite samples, were taken as model materials and analyzed. Surface area was determined by using both NSA and N≩I2 techniques, and the difference between the results given by the two techniques were observed and related to the microstructure, which was analyzed by using X-ray diffraction, Raman spectroscopy, and the oxygen content was measured by using elementary analysis. Two different models of iodine adsorption have been proposed, respectively, for the graphitic parts of the graphite grains and for the disordered part of the grains. An analytical relationship between the differences of iodine and nitrogen surface area values, microstructure and oxygen content was proposed and successfully tested. The same relationship was applied to some commercial and experimental carbon black with good results.

scholarly journals Characterization of Municipal Solid Waste Incineration and Flue Gas Emission Under Anoxic Environment in Tibet Plateau

2021 ◽  
Author(s):  
Dan Zeng ◽  
Wenwu Zhou ◽  
Peng Zhou ◽  
Yuechi Che ◽  
Zhiyong Han ◽  
...  
Keyword(s):  
Oxygen Content ◽  
Flue Gas ◽  
Waste Incineration ◽  
Tibet Plateau ◽  
Low Oxygen ◽  
Gas Emission ◽  
High Oxygen Content ◽  
Msw Incineration ◽  
Air Temperatures ◽  
Plateau Area

Abstract Waste incineration is a process of full combustion reaction between waste and oxygen at high temperature. It is a new problem whether the special natural environmental conditions of Tibet Plateau, such as low air pressure, low oxygen content and low temperature, will affect the waste incineration in the plateau area. In this work, the influence of different parameters on MSW incineration efficiency and flue gas emission were investigated. The results showed that the temperatures exhibited a significant impact on the flue gas emission. Under the lower temperature, CO was determined to be the main pollutant. With the increase of temperature, NOx became the main pollutant. The optimal temperature range of flue gas emission was between 800ºC to 900ºC. A slight negative pressure in incinerator was benefit for incineration system safety and flue gas emissions. The optimal range was -50Pa to 0Pa. Lower oxygen content (3%-6%) in the incinerator affected the incineration efficiency and flue gas emission. Meanwhile, the high oxygen content had no obvious impact on the flue gas emission, but the cost increased and the service life of the incinerator was affected. The optimal oxygen content in the incinerator was controlled at 6%-8%. Furthermore, the air temperatures, pressures and oxygen content in the natural environment had no significant effect on MSW incineration process. Increasing the air volume would bring about the increase of N 2 in the incinerator. This work provides the basic data support for MSW incineration technology in plateau area.

The Effect of Oxygen on the Thermal Stability of Si1−xGex Strained Layers Grown by Limited Reaction Processing

1991 ◽  
Vol 220 ◽  
Author(s):  
D. B. Noble ◽  
J. L. Hoyt ◽  
P. Kuo ◽  
W. D. Nix ◽  
J. F. Gibbons ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Solid Solution ◽  
Oxygen Content ◽  
Low Oxygen ◽  
Strained Layers ◽  
High Oxygen Content ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Effect Of Oxygen ◽  
Content Support

ABSTRACTSi1−xGex layers containing 2×1020 oxygen atoms/cm3 exhibit an enhancement in thermal stability when compared to similar films (comparable Ge content and thickness) with 2 orders of magnitude less oxygen. X-ray measurements of the lattice constants in the strained films indicate that the oxygen does not substantially change the amount of strain in the layers. A prediction of the effect of oxygen based on solid solution strengthening theory is shown to be consistent with experimental annealing results. In addition, experimental measurements of slower misfit dislocation velocities in the layers with high oxygen content compared to those measured in films with low oxygen content, support the idea of solid solution strengthening. It is therefore likely that oxygen impedes the kinetics of dislocation formation.

High Performance Magnets - Microstructure and Coercivity

1999 ◽  
Vol 577 ◽  
Author(s):  
J. Fidler ◽  
S. Sasaki ◽  
E. Estevez-Rams
Keyword(s):  
Energy Density ◽  
Oxygen Content ◽  
Coercive Field ◽  
High Performance ◽  
Magnetic Energy ◽  
Low Oxygen ◽  
Critical Temperatures ◽  
High Oxygen Content ◽  
Magnetic Energy Density ◽  
Strip Cast

ABSTRACTThe importance of newly developed permanent magnetic materials in many electro-, magnetomechanical and electronic applications can be attributed to the drastic improvement of the magnetic energy density product and coercive field. A systematic study has been undertaken in order to determine the influence of oxygen content on microstructure and coercivity of high remanence Nd2Fe14B based sintered magnets. The energy density product >400 kJ/m3 (50 MGOe) and the coercive field of 800 kA/m were obtained after a combination of rubber isostatic and transverse die pressing methods. Magnets of the composition Nd151−xFe78+xB6Cu0.03A10.7 [x= 0-2.5] were prepared using strip cast materials. The high oxygen content of the magnets was gradually decreased from values of 4000-6000 ppm to a value < 1000 ppm. Abnormal grain growth (AGG) of the 2:14:1 grains occurred preferentially in magnets with low oxygen content, thus the squareness of the demagnetisation curve drastically decreased. The oxygen content strongly affects the AGG and the magnets with higher oxygen content have the higher critical temperatures at which the AGG occurs. On the other hand, isotropic magnets tend to have the lower critical temperatures than anisotropic magnets by 10-20°C. In the second part of the paper examples of the influence of intergranular phases, grain size and grain shape observed by TEM on coercivity of sintered and melt-spun Nd-Fe-B magnets are compared.

Radiative Properties of Y-Ba-Cu-0 Films With Variable Oxygen Content

1992 ◽  
Vol 114 (4) ◽  
pp. 958-964 ◽  
Author(s):  
B. I. Choi ◽  
Z. M. Zhang ◽  
M. I. Flik ◽  
T. Siegrist
Keyword(s):  
Oxygen Content ◽  
Optical Constants ◽  
Deposition Process ◽  
Film Deposition ◽  
Radiative Properties ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Thin Film Optics ◽  
Electron Contribution ◽  
Measurement And Control

The room-temperature radiative properties of YBa2Cu3O7−δ superconducting films with varying oxygen content (δ = 0 to 1) on a LaAlO3 substrate are investigated. The fitting of reflectance spectra using thin-film optics and the Drude-Lorentz model function with multiple oscillators determines the optical constants. The film with high oxygen content (δ = 0) has a metallic optical behavior. A decrease in the oxygen content causes a removal of free carriers, and the film with low oxygen content (δ = 1) acts like a dielectric with a very weak free-electron contribution. Knowledge of the optical constants of oxygen-deficient YBa2Cu3O7-δ films facilitates accurate substrate temperature measurement and control during the film deposition process.

scholarly journals Effect of alloying elements (Zr, Hf, Co), heat and mechanical treatment conditions on the phase composition and magnetic properties of SmFe11Ti compounds with ThMn12 structure

2018 ◽  
Vol 185 ◽  
pp. 04026 ◽  
Author(s):  
Andrey Urzhumtsev ◽  
Maksim Anikin ◽  
Evgeniy Tarasov ◽  
Mikhail Semkin ◽  
Maksim Cherepkov ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Mechanical Treatment ◽  
Annealing Temperature ◽  
Magnetic Hysteresis ◽  
High Energy ◽  
Magnetic Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treatment Conditions ◽  
Hysteresis Properties

The results of thermomagnetic, metallographic and X-ray diffraction phase analysis as well as the measurements of specific magnetization (σs), Curie temperature (TC), coercive force (HC) of (Sm,M)(Fe,M)12-xTix alloys samples, where M = Zr, Hf, Co with the ThMn12 main phase structure (1-12) are presented. The effect of the annealing temperature and the cooling rate on the formation of 1-12 phase and its magnetic properties, including the effect of high-energy milling on the magnetic hysteresis properties and alloys structure are described. It was found that the highest magnetic characteristics such as σs = 112.6 emu/g and TC = 600 ºC are attained in the (Sm0.8Zr0.2)(Fe0.75Co0.25)11.4Ti0.6 alloy after its annealing at 1050 °C and rapid cooling. It is noted that a mechanical milling of the alloy leads to 1-12 phase amorphization which accompanied by an α-(Fe) or metal Co phases impurity formation.

Grain Boundary Modification by Si3N4 Additions and the Effect on Corrosion Behaviors in Two Sintered Nd-Fe-B Magnets

2010 ◽  
Vol 89-91 ◽  
pp. 733-738
Author(s):  
Qiong Zhen Liu ◽  
Lan Ting Zhang ◽  
Ai Dang Shan ◽  
Jian Sheng Wu ◽  
Matahiro Komuro
Keyword(s):  
Grain Size ◽  
Corrosion Resistance ◽  
Oxygen Content ◽  
Corrosion Potential ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Intergranular Phase ◽  
Microstructure Observation ◽  
Corrosion Behaviors ◽  
Boundary Modification

Two sintered magnets Nd15Dy1.2Fe77Al0.8B6 and Nd22Fe71B7 were modified by intergranular additions of Si3N4. The remanence as well as sintering density of the two magnets increased slightly with appropriate amount of Si3N4 additives. Meanwhile, there was an obvious increase in coercivity of the Nd-rich Nd22Fe71B7 magnet after 0.3 wt. % Si3N4 was added to magnets. Besides the effects on magnetic properties, an improved corrosion resistance was observed. Compared with the native magnets without any additions, corrosion potential of the magnets with Si3N4 additives is more positive and the current density in the anodic branch of the polarization curve is reduced. Microstructure observation reveals that Si3N4 additives have been incorporated into the intergranular phases in the magnets. Si is found to enrich in the Nd-rich intergranular phase with low oxygen content. With the introduction of Si3N4 additives, more intergranular phase with high oxygen content is formed, which may contribute to improved corrosion resistance. In addition, addition of Si3N4 refines the grain size of Nd22Fe71B7.

Properties of Indium Molybdenum Oxide Films Fabricated Via High-Density Plasma Evaporation at Room Temperature

2005 ◽  
Vol 20 (1) ◽  
pp. 247-255 ◽  
Author(s):  
Shi-Yao Sun ◽  
Jow-Lay Huang ◽  
Ding-Fwu Lii
Keyword(s):  
Oxygen Content ◽  
Molybdenum Oxide ◽  
Room Temperature ◽  
Weight Ratio ◽  
Optical Transmittance ◽  
High Density ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Average Optical Transmittance ◽  
Density Plasma

The goal of this study was to determine the scattering mechanisms and investigate the optoelectronic properties of indium molybdenum oxide (IMO) films. IMO films were deposited from an In2O3/MoO3 target with a weight ratio of 99/1, 95/5 and 90/10 via high-density plasma evaporation at room temperature. Based on the structural, electrical and optical properties, this study proposed that the neutral complex [(2Mo‧In)Oi″]x dominated at high doping content and high oxygen content, whereas ionized complex Mo‧‧‧In Oi″]‧ dominated at low doping level or low oxygen content. Uniform 99/1 IMO films with minimum resistivity of 3.56 × 10−4 Ω cm (corresponding to a mobility of 14.6 cm2V−1s−1 and carrier concentration of 14.3 × 1020 cm−3) and average visible transmittance of ∼85% were produced at an optimum oxygen content of ∼9%. Average optical transmittance exceeding 80% was demonstrated, and a structural change appeared at low oxygen contents.

Carbon and the Kinetics of Oxygen Precipitation in Silicon

1982 ◽  
Vol 14 ◽  
Author(s):  
R.F. Pinizzotto ◽  
S. Marks
Keyword(s):  
Oxygen Content ◽  
Oxygen Concentration ◽  
Carbon Concentration ◽  
Oxygen Solubility ◽  
Low Oxygen ◽  
Subsequent Increase ◽  
High Oxygen Content ◽  
Oxygen Precipitation ◽  
Precipitate Growth ◽  
Initial Oxygen

ABSTRACTOxygen precipitation in Czochralski silicon has been studied as a function of anneal time, oxygen concentration and carbon concentration using FTIR. It was found that the oxygen supersaturation controls the precipitation kinetics in high oxygen content samples, whereas the carbon concentration is of prime importance in low oxygen content samples. The decrease in sustitutional carbon concentration after nucleation and its subsequent increase with extended growth anneals supports the view that carbon affects precipitate nucleation, but not precipitate growth. The measured oxygen solubility at 1000°C was found to depend on both the initial oxygen concentration and the initial carbon concentration.

The VO Defect in Electron Irradiated Czochralski Silicon

2014 ◽  
Vol 1004-1005 ◽  
pp. 293-296
Author(s):  
Li Li Cai ◽  
Hui Bin Wang ◽  
Cui Ju Feng ◽  
Gui Feng Chen
Keyword(s):  
Thermal Stability ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Oxygen Content ◽  
Irradiation Dose ◽  
Linear Increase ◽  
Interstitial Oxygen ◽  
Low Oxygen ◽  
High Oxygen Content ◽  
Czochralski Silicon

The Czochralski silicon (CZ-Si) samples were irradiated with 1.5 MeV electrons and annealed at 200 - 450 °C. It was investigated the effect of irradiation dose and interstitial oxygen content [Oi] on VO concentration by Fourier transform infrared spectroscopy (FTIR). The results show that VO concentration increases with irradiation dose but not linear increase. The interstitial oxygen content has no effect on VO concentration. The VO intensity increases firstly and then decreases after annealing in samples with low oxygen content. The VO disappears at 450 °C. In high oxygen content samples, VO exhibits thermal stability and disappears at 400 °C.

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