scholarly journals Microstructure and magnetic properties of soft nickel ferrite

2015 ◽  
Vol 39 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Mahabub Alam Bhuiyan ◽  
Sheikh Manjura Hoque ◽  
Shamima Choudhury
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Sintering Temperature ◽  
Great Influence ◽  
Complex Permeability ◽  
Scanning Electron Micrographs ◽  
Academy Of Sciences ◽  
Curie Temperature Tc ◽  
Microstructure And Magnetic Properties

Polycrystalline NiFe2O4 samples were prepared from analytical grade powder of NiO and Fe2O3 by conventional double sintering technique. The samples were sintered at 1000 - 1400°C. The scanning electron micrographs (magnification ´ 10000) of the samples revealed that the grain size increases and the porosity decreases with the increase in sintering temperature. These changes in microstructure, grain size and porosity with sintering temperature have great influence on the magnetic properties of NiFe2O4. Complex permeability (u’) over the frequency range from 1 kHz to 13 MHz for the samples at different sintering temperatures (1000-1400°C) has been observed. Variation of permeability with the applied temperature has been observed at various sintering temperature from which Curie temperature have been calculated. Decreased value of Curie temperature (Tc) has been found with the increase of sintering temperature.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 59-64, 2015

scholarly journals Effects of sintering temperature on microstructure and magnetic properties of NiFe2O4 prepared from nano size powder of NiO and Fe2O3

1970 ◽  
Vol 34 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Mahabub Alam Bhuiyan ◽  
Sheikh Manjura Hoque ◽  
Shamima Choudhury
Keyword(s):  
Magnetic Properties ◽  
Sintering Temperature ◽  
Great Influence ◽  
Initial Permeability ◽  
X Ray Diffraction ◽  
Wet Chemical ◽  
Diffraction Patterns ◽  
Academy Of Sciences ◽  
Nano Size ◽  
Size Powder

Polycrystalline NiFe2O4 was prepared by solid state reaction from nano size powder of NiO and Fe2O3 which were synthesized by wet chemical method. The inverse spinel single phase of the sample has been confirmed by the X-ray diffraction patterns. SEM micrographs of the samples revealed that the grain size increases and the porosity decreases with the increase in sintering temperature and has great influence on the magnetic properties of NiFe2O4 . Enhancement of real part of initial permeability (μ′) as a function of frequency has been observed with the increase in sintering temperature. Temperature dependence real part of initial permeability has been observed at various sintering temperature and gives the manifestation of Hopkinson effect. Variation of Curie temperature (Tc) has been found with the variation of sintering temperature. Key words: Sintering temperature; Microstructure; Magnetic properties DOI: 10.3329/jbas.v34i2.6865Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 189-195, 2010

Doping Effect of W6+ Ions on Microstructural and Magnetic Properties of Mn-Zn Ferrites

2012 ◽  
Vol 512-515 ◽  
pp. 1408-1411
Author(s):  
Qing Kai Xing ◽  
Zhi Jian Peng ◽  
Cheng Biao Wang ◽  
Zhi Qiang Fu ◽  
Xiu Li Fu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Saturation Magnetization ◽  
Initial Permeability ◽  
Doping Content ◽  
Additional Doping ◽  
Ion Doping ◽  
Cubic Structure ◽  
Microstructure And Magnetic Properties

Mn-Zn ferrites with different doping contents of W6+ ions were prepared by using standard ceramic technique. The microstructure and magnetic properties of the as-prepared Mn-Zn ferrites were investigated. It was found that all the samples with different contents of W6+ ions consisted of ferrite phase of typical spinel cubic structure. With increasing doping content of W6+ ions, the lattice constant of the ferrites decreased but the grain size increased. Through the measurement of magnetic properties, it was revealed that the saturation magnetization and initial permeability of the samples increased with small doping content of W6+ ions but decreased with additional doping, and the Curie temperature decreased monotonously with W6+ ion doping.

Effect of Nitridation Magnetic Properties of Nanocrystalline Fe-Co Alloy Powders

2010 ◽  
Vol 654-656 ◽  
pp. 1106-1109
Author(s):  
Ya Qiong He ◽  
Chang Hui Mao ◽  
Jian Yang
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
High Energy ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron ◽  
Nitridation Temperature ◽  
Microstructure And Magnetic Properties

Nanocrystalline Fe-Co alloy powders, which were prepared by high-energy mechanical milling, were nitrided under the mixing gas of NH3/H2 in the temperature range from 380°C to 510°C. X-ray diffraction (XRD) was used to analyze the grain size and reaction during the processing. The magnetic properties of the nitrided powders were measured by Vibrating Sample Magnetometer (VSM). The results show that with the appearance of Fe4N phase after nitride treatment, and the grain-size of FeCo phase decreases with the increase of nitridation temperature between 380°C to 450°C.The saturation magnetization of nitrided alloy powder treated at 480°C is about 18% higher than that of the initial Fe-Co alloy powder, accompanied by the reduction of the coercivity. Transmission electron microscope (TEM) was used, attempting to further analyze the effect of Fe4N phase on microstructure and magnetic properties of the powder mixtures.

MICROSTRUCTURE AND MAGNETIC PROPERTIES OF NANOSTRUCTURED Al2O3-20vol%Fe70Co30 COMPOSITE PREPARED BY HIGH ENERGY MECHANICAL MILLING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1383-1388 ◽  
Author(s):  
MASLEEYATI YUSOP ◽  
DELIANG ZHANG ◽  
MARCUS WILSON ◽  
NICK STRICKLAND
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
Milling Time ◽  
High Energy ◽  
Composite Powders ◽  
Nanostructured Composite ◽  
Alloy Particles ◽  
Average Grain Size ◽  
Microstructure And Magnetic Properties

Al 2 O 3-20 vol % Fe 70 Co 30 composite powders have been prepared by high energy ball milling a mixture of Al 2 O 3 powder and Fe 70 Co 30 alloy powder. The Fe 70 Co 30 alloy powder was also prepared by mechanical alloying of Fe and Co powders using the same process. The effects of milling duration from 8 to 48 hours on microstructure and magnetic properties of the nanostructured composite powders have been studied by means of X-ray Diffractometry (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). It was found that the nanostructured composite powder particles with irregular shapes and Fe 70 Co 30 alloy particles being embedded in them formed after 8 hours of milling. The average grain size of the Al 2 O 3 matrix reduced drastically to less than 18nm after 16 hours of milling. On the other hand, the embedded alloy particles demonstrated almost unchanged average grain size in the range of 14-15nm. Magnetic properties of the powder compacts at room temperature were measured from hysteresis curves, and show strong dependence of the milling time, with the coercivity increasing from 67.1 up to 127.9kOe with increasing the milling time from 8 to 48 hours. The possible microstructural reasons for this dependence are discussed.

scholarly journals Effect of Ca-substitution on the Magnetic and Dielectric Properties of Mn-Zn Ferrites

2012 ◽  
Vol 4 (2) ◽  
pp. 297 ◽  
Author(s):  
M. M. Rahman ◽  
P. K. Halder ◽  
F. Ahmed ◽  
T. Hossain ◽  
M. Rahaman
Keyword(s):  
Dielectric Constant ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Sintering Temperature ◽  
Initial Permeability ◽  
Q Factor ◽  
Dielectric Polarization ◽  
Ca Substitution ◽  
Magnetic And Dielectric Properties ◽  
Curie Temperature Tc

Spinel Mn-Zn ferrites with composition MnxZn0.4Ca0.6-2xFe2+xO4, where x = 0.10, 0.15, 0.20, 0.25 and 0.30 have been prepared by conventional ceramic technique sintered at    1300 °C for 4 hours. The influence of Ca-substitution on various properties of Mn-Zn ferrites have been studied in this work. Investigations were carried out by the measurements of Curie temperature, permeability, loss tangent, Q-factor, dielectric constant and AC resistivity of the samples. Curie temperature (Tc), the real part of initial permeability (µ´), loss tangent (tan ?), and AC resistivity have been found to be decreased while the Q-factor increases with the increase in Ca-content. The frequency characteristics of the dielectric constant and AC resistivity have been found to be decreased as the frequency increases. Maxwell-Wagner interfacial type of dielectric polarization was observed with the addition of Ca-content over the entire range of frequency considered. Keywords: Spinel ferrites; Sintering temperature; Initial permeability; Dielectric constant.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.9752 J. Sci. Res. 4 (2), 297-306 (2012)

Magnetic Properties and Magnetostriction of ZnxNi1-x MnSb Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 1715-1718
Author(s):  
S.K. Ren ◽  
G.B. Ji ◽  
Song Ling Huang ◽  
Q.Q. Cao ◽  
Feng Ming Zhang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Structural Phase ◽  
Solid State Reaction Method ◽  
Experimental Result ◽  
Xrd Pattern ◽  
Zn Concentration ◽  
Magnetostriction Coefficient ◽  
The Relationship ◽  
Curie Temperature Tc

We have investigated the magnetic properties and magnetostriction of ZnxNi1-xMnSb compounds prepared by solid state reaction method. It is found that for x less than 0.6 the magnetization of ZnxNi1-xMnSb almost remains unchanged. However, when x is larger than 0.6 the magnetization starts to drop linearly. Experimental result indicates that at low Zn concentrations, x < 0.7, the Curie temperature (TC) decreases with increasing Zn concentration x. However, when x > 0.7, the Curie temperature increases distinctly with increasing x. The Zn concentrartion dependence of magnetostrictive ceofficient is also studied. The experimental curve shows that when x < 0.6 the value of magnetostriction coefficient for ZnxNi1-xMnSb decreases linearly with the increasing Zn concentration x. However, when x is above 0.6, the magnetostrictive ceofficient raises distinctly. By analyzing the XRD pattern, the structures of the materials are examined and the relationship between the properties and the structures are discussed. A structural phase transition is observed. It has been indicated that the structure plays an important role in the magnetic and magnetostrictive properties of the system.

Structural, Morphological and Composition Analysis of Nanocrystalline La0.67Ba0.33MnO3 Powder

2012 ◽  
Vol 584 ◽  
pp. 239-242
Author(s):  
C. Seshendra Reddy ◽  
A. Sivasankar Reddy ◽  
P. Sreedhara Reddy
Keyword(s):  
Grain Size ◽  
Sintering Temperature ◽  
Base Material ◽  
Solid State Reaction Method ◽  
Rhombohedral Structure ◽  
Composition Analysis ◽  
Scanning Electron Micrographs ◽  
Atomic Force ◽  
Average Grain Size ◽  
Composition Properties

La0.67Ba0.33MnO3 powders were successfully prepared by a standard solid state reaction method, and systematically investigated the influence of the sintering temperature on the structural, microstructure, composition properties. The XRD pattern showed that the as prepared LBMO material was in single-phase with rhombohedral structure. From the scanning electron micrographs, it was observed that the grain size increased with sintering temperature and the average grain size was ~40nm.The surface roughness was measured by atomic force microscope and the RMS roughness of samples was in the range 48 to 85 nm. The as prepared samples exhibited nearly the same composition of the base material.

EFFECT OF COPPER OXIDE ON THE GRAIN GROWTH AND INITIAL PERMEABILITY OF Mg–Cu–Zn FERRITES

2010 ◽  
Vol 24 (02) ◽  
pp. 169-182
Author(s):  
M. MANJURUL HAQUE ◽  
M. HUQ ◽  
SYED FARID UDDIN FARHAD ◽  
JASIM UDDIN KHAN ◽  
M. A. HAKIM
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Grain Growth ◽  
Spinel Phase ◽  
Initial Permeability ◽  
Cu Content ◽  
Average Grain Size ◽  
Zn Ferrite ◽  
Effect Of Copper ◽  
Microstructure And Magnetic Properties

The microstructure and magnetic properties of Mg – Cu – Zn ferrites prepared by using solid-state reaction method have been investigated. X-ray diffraction (XRD), a scanning electron microscope (SEM), impedance analyzer and a vibrating sample magnetometer (VSM) were utilized in order to study the effect of copper substitution and its impact on the crystal structure, grain size, microstructure and magnetic properties of the Mg – Cu – Zn ferrite. The formation of cubic spinel phase was identified using XRD technique. The microstructures of the samples show that the grain growth is greatly enhanced by the addition of CuO which is attributed to the liquid phase during sintering. The average grain size (Dm) increases significantly with increasing Cu content. The initial permeability (μ') of the samples increases appreciably with increasing Cu content which is attributed to the increase of grain size and density of the samples. The resonance frequency (fr) of the samples shifts toward the lower frequency as the Cu content increases. The sharp fall of μ' in μ'-T curves is observed for all the samples which indicate the homogeneity of the samples. The saturation magnetization (Ms) of the Mg – Cu – Zn ferrites increases slightly with increasing Cu concentration.

Effects of Sputtering Conditions on Texture, Microstructure and Magnetic Properties of the CoCrPt/NiAl Thin Films

1998 ◽  
Vol 517 ◽  
Author(s):  
Y.-N. Hsu ◽  
D. E. Laughlin ◽  
D. N. Lambeth
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Magnetic Properties ◽  
Optimum Pressure ◽  
Grain Sizes ◽  
Maximum Value ◽  
Sputtering Power ◽  
Sputtering Pressure ◽  
The Relationship ◽  
Microstructure And Magnetic Properties

AbstractThe effects of sputtering argon pressures and sputtering power on the microstructure, texture and magnetic properties of NiAI underlayers on CoCrPt films were investigated. In this paper, the relationship between the sputtering conditions, microstructure, crystallographic texture and magnetic properties of these thin films will be discussed. By controlling the sputtering pressure and sputtering power, the texture and microstructure of NiAI underlayers were found to vary. This in turn was found to influence the magnetic properties of CoCrPt thin films. It was found that 10 mtorr is the optimum pressure to deposit the NiAl thin films to obtain the best magnetic properties for our system. At this argon pressure, the coercivity reached a maximum value because of the strongest CoCrPt (1010) texture and smallest grain size. At lower argon pressures (< 10 mtorr), NiAI tended to have a (110) texture reducing the CoCrPt (1010) texture, which in turn reduced the CoCrPt coercivity and S*. Also, high NiAl deposition pressures (>30 mtorr) yielded larger grains and a weaker CoCrPt (1010) texture, thereby decreasing the coercivity of the CoCrPt films. Increasing the sputtering power has been found to increase the CoCrPt coercivity and S* value. However, the grain sizes of the CoCrPt/NiAl thin films deposited at higher sputtering power were larger than those obtained at lower sputtering power.

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