scholarly journals Microstructure and Superparamagnetic Properties of Mg-Ni-Cd Ferrites Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. M. Eltabey ◽  
A. M. Massoud ◽  
Cosmin Radu
Keyword(s):  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Anisotropy Constant ◽  
Blocking Temperature ◽  
Zero Field ◽  
Effective Anisotropy Constant ◽  
Crystallite Sizes ◽  
Coprecipitation Route ◽  
Average Size ◽  
Field Cooling

Magnesium substituted nickel cadmium ferrite nanoparticles MgxNi0.6−xCd0.4Fe2O4(fromx= 0 to 0.6 with step 0.1) have been synthesized by the chemical coprecipitation route. X-ray diffraction (XRD) and infrared spectroscopy (FTIR) revealed that the obtained powders have a single phase of cubic spinel structure. The crystallite sizes calculated from XRD data have been confirmed using transmission electron microscopy (TEM) showing that the powders are consisting of nanosized grains with an average size range 5–1.5 nm. Magnetic hysteresis loops were traced at 6.5 K as well as at room temperature using VSM. It was found that, due to the Mg2+-ions substitution, the values of saturation magnetizationMsfor the investigated samples were decreased, whereas the coercive fieldHcincreased. Both zero field cooling (ZFC) and field cooling (FC) curves are measured in the temperature range (6.5–350 K) and the values of blocking temperatureTBwere determined. No considerable variation in the values ofTBwas observed with increasing Mg-content, whereas the values of the effective anisotropy constantKeffwere increased.

scholarly journals Iron-Doped Lithium Tantalate Thin Films Deposited by Magnetron Sputtering: A Study of the Iron Role in the Structure and the Derived Magnetic Properties

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Sergio David Villalobos Mendoza ◽  
José Trinidad Holguín Momaca ◽  
José Trinidad Elizalde Galindo ◽  
Diana María Carrillo Flores ◽  
Sion Federico Olive Méndez ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Blocking Temperature ◽  
Ferromagnetic Behavior ◽  
Zero Field ◽  
Cooling Curves ◽  
X Ray Diffraction ◽  
Field Cooling

Fe-doped LiTaO3 thin films with a low and high Fe concentration (labeled as LTO:Fe-LC and LTO:Fe-HC, respectively) were deposited by magnetron sputtering from two home-made targets. The dopant directly influenced the crystalline structure of the LiTaO3 thin films, causing the contraction of the unit cell, which was related to the incorporation of Fe3+ ions into the LiTaO3 structure, which occupied Li positions. This substitution was corroborated by Raman spectroscopy, where the bands associated with Li-O bonds broadened in the spectra of the samples. Magnetic hysteresis loops, zero-field cooling curves, and field cooling curves were obtained in a vibrating sample magnetometer. The LTO:Fe-HC sample demonstrates superparamagnetic behavior with a blocking temperature of 100 K, mainly associated with the appearance of Fe clusters in the thin film. On the other hand, a room temperature ferromagnetic behavior was found in the LTO:Fe-LC layer where saturation magnetization (3.80 kAm−1) and magnetic coercivities were not temperature-dependent. Moreover, the crystallinity and morphology of the samples were evaluated by X-ray diffraction and scanning electron microscopy, respectively.

scholarly journals Magnetic properties of iron oxide nanoparticles with a DMSA-modified surface

2021 ◽  
Vol 242 (1) ◽  
Author(s):  
K. Winiarczyk ◽  
W. Gac ◽  
M. Góral-Kowalczyk ◽  
Z. Surowiec
Keyword(s):  
Magnetic Properties ◽  
Magnetite Nanoparticles ◽  
Magnetic Hysteresis ◽  
Blocking Temperature ◽  
Synthesis Process ◽  
Physical Parameters ◽  
Zero Field ◽  
Powder Samples ◽  
Surface Modified ◽  
Field Cooling

AbstractThe magnetic properties of magnetite nanoparticles (Fe3O4 NPs) strongly depend on their chemical and physical parameters, which can be regulated by a controlled synthesis process. To improve the quality of the obtained nanoparticles, their surface is often modified with organic compounds (from the group of surfactants, sugars, proteins, or organic acid). In this study, we synthesized magnetite nanoparticles with a surface modified with the organic compound DMSA. Then, the nanocrystallites were characterized in terms of structure and morphology. To investigate the role of DMSA and to understand the adsorption mechanism, FTIR measurements were carried out. Using Mössbauer spectroscopy, we investigated temperature-induced changes in the magnetic properties of prepared samples. The spectra were recorded in a wide temperature range (from 4 K to 390 K) for two types of samples: powders and ferrofluids with various concentrations. In the case of powder samples, the superparamagnetic doublet appeared at room temperature. For magnetic suspensions, the spectra were more complicated. They consisted of superposition of asymmetrically broadened sextets and doublets, which was caused by the occurrence of long-range dipole-dipole interactions. These interactions affected the magnetic properties of the material and increased the blocking temperature. Additionally, the magnetic hysteresis and zero field cooling-field cooling (ZFC/FC) curves were measured with the use of a vibrating sample magnetometer.

scholarly journals Magnetic characterization of nanocrystalline iron samples with different size distributions

2014 ◽  
Vol 32 (3) ◽  
pp. 423-429 ◽  
Author(s):  
Janusz Typek ◽  
Grzegorz Zolnierkiewicz ◽  
Rafal Pelka ◽  
Karolina Kielbasa ◽  
Walerian Arabczyk ◽  
...  
Keyword(s):  
Hysteresis Loops ◽  
Anisotropy Field ◽  
Microwave Frequency ◽  
Anisotropy Constant ◽  
Nanocrystallite Size ◽  
Crystallite Sizes ◽  
Nanocrystalline Iron ◽  
Effective Magnetization ◽  
Average Size

AbstractNanocrystalline iron was obtained by fusing magnetite and promoters. The oxidized form was reduced with hydrogen and passivated (sample P0). The average nanocrystallite size in sample P0 was d(P0) =16 nm and the width of size distribution was σ(P0) = 18 nm. Samples of nanocrystalline iron with narrower diameter ranges and larger and smaller average crystallite sizes were also synthesized. They were: sample P1 (d(P1) = 28 nm, σ(P1) = 5 nm), sample P2 (d(P2) = 22 nm, σ(P1) = 5 nm), sample P3 (d(P3) = 12 nm, σ(P1) = 9 nm). These four samples were studied at room temperature by dc magnetization measurements and ferromagnetic resonance at microwave frequency. Correlations between samples sizes distributions (average size and width of the sizes) and magnetic parameters (effective magnetization, anisotropy field, anisotropy constant, FMR linewidth) were investigated. It was found that the anisotropy field and effective magnetization determined from FMR spectra scale linearly with nanoparticle sizes, while the effective magnetic anisotropy constant determined from the hysteresis loops decreases with nanoparticle size increase.

Structure and Magnetic Properties of Co2.73Fe0.27O4 Synthesized by the Heat-Decomposition Method

2011 ◽  
Vol 181-182 ◽  
pp. 352-355
Author(s):  
Zhang Hua Gan ◽  
Jun Bo Guo ◽  
Jing Liu ◽  
Zhi Hong Lu
Keyword(s):  
Decomposition Method ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Annealing Treatment ◽  
Exchange Interactions ◽  
Xrd Analysis ◽  
Zero Field ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Field Cooling

Co2.73Fe0.27O4 nanoparticles were synthesized using the heat-decomposition method followed by annealing treatment. X-ray diffraction (XRD) analysis shows that most of the peaks are close to the data for antiferromagnetic Co3O4, while weak peaks of CoFe2O4 are also detected. It indicates that the prepared particles can be reckoned as a composite with a small size of the FM particles embed in a large thickness of the AFM matrix. The magnetic hysteresis loops of Co2.73Fe0.27O4 powders were measured at 10 K by using the zero-field cooling (ZFC) and field cooling (FC) procedures and show negative and downward shifts, and the shifts finally disappear when temperature increases to 200 K. We suggest that exchange bias effect in Co2.73Fe0.27O4 is mainly related with the exchange interactions at the interfaces between the FM CoFe2O4 nanoparticles and the frozen spins around them.

Exchange Bias Properties in Bulk Ni45Co5Mn38Sn12 Heusler Alloy

2014 ◽  
Vol 875-877 ◽  
pp. 272-276 ◽  
Author(s):  
Chao Jing ◽  
Ye Jun Yang ◽  
Dong Hua Yu ◽  
Zhe Li ◽  
Xiao Long Wang ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Exchange Bias ◽  
Heusler Alloy ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Bias Field ◽  
Magnetic Hysteresis Loop ◽  
Zero Field ◽  
Co Substitution ◽  
Exchange Bias Field

We report the exchange bias properties in the bulk Ni45Co5Mn38Sn12quaternary Heusler alloy. The ferromagnetic (FM) –antiferromagnetic (AFM) interactions get reinforced after the Co substitution for Ni in the Ni-Mn-Sn alloy, which increase the exchange bias field (HE). A maximum shift in hysteresis loops of 306 Oe was observed in the 10 kOe field cooled sample. The origin of this large exchange bias field has been discussed. Magnetic hysteresis loop obtained in the zero field cooled (ZFC) mode shows double-shifted loop, and the reason of this phenomenon has been explained in detail.

scholarly journals Magnetic Cobalt and Cobalt Oxide Nanoparticles in Hyperbranched Polyester Polyol Matrix

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
O. I. Medvedeva ◽  
S. S. Kambulova ◽  
O. V. Bondar ◽  
A. R. Gataulina ◽  
N. A. Ulakhovich ◽  
...  
Keyword(s):  
Magnetic Hysteresis ◽  
Average Diameter ◽  
Physicochemical Characteristics ◽  
Blocking Temperature ◽  
Zero Field ◽  
Hyperbranched Polyester ◽  
Polyester Polyol ◽  
Cobalt Oxide Nanoparticles ◽  
Ft Ir ◽  
Co Nanoparticles

A series of cobalt (Co) and its oxides based nanoparticles were synthesized by using hyperbranched polyester polyol Boltorn H20 as a platform and sodium borohydride as a reducing agent. UV, FT-IR, XRD, NTA, and TEM methods were employed to obtain physicochemical characteristics of the products. The average diameter of Co nanoparticles was approximately 8.2±3.4 nm. Their magnetic properties, including hysteresis loop, field-cooled, and zero field-cooled curves were investigated. The nanoparticles exhibit superparamagnetism at room temperature, accompanied by magnetic hysteresis below the blocking temperature.

Effects of Na-Doping on Structure and Magnetic Properties of LaCoO3

2017 ◽  
Vol 727 ◽  
pp. 403-409
Author(s):  
Yi Hao Shen ◽  
Qing Rong Yao ◽  
Peng Cheng Yang ◽  
Jian Qiu Deng ◽  
Zong Min Wang
Keyword(s):  
Magnetic Properties ◽  
Structure Refinement ◽  
Hexagonal Phase ◽  
Sol Gel ◽  
Rhombohedral Structure ◽  
Zero Field ◽  
Ferromagnetic Transition ◽  
Na Doping ◽  
Crystallite Sizes ◽  
Field Cooling

Effect of Na doping on the structural and magnetic properties of La1-xNaxCoO3 (0≤x≤0.4) nanopowder samples synthesized by sol-gel method have been investigated. Rietveld crystal structure refinement of the X-ray diffraction data shows that La1−xNaxCoO3 (x≤0.3) crystallizes in the rhombohedral structure with space group . The lattice parameters decrease and the crystallite sizes increase with the increase of x. For the sample with x=0.4, a secondary hexagonal phase NaCo2O4 was observed. The zero field cooling (ZFC) and field cooling (FC) curve of the samples (x≤0.3) exhibit a paramagnetic-ferromagnetic transition with decreasing temperature.

Oscillatory Angular Dependence of Exchange Bias for Epitaxial NiO-Co (001) Bilayers

2001 ◽  
Vol 674 ◽  
Author(s):  
S. Dubourg ◽  
J.F. Bobo ◽  
B. Warot ◽  
E. Snoeck ◽  
J.C. Ousset
Keyword(s):  
Magnetic Field ◽  
Exchange Bias ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Field Application ◽  
Zero Field ◽  
Sign Change ◽  
Realistic Description ◽  
Sputter Deposited ◽  
The Magnetic Field

ABSTRACTWe have sputter-deposited NiO-Co bilayers on MgO (001) substrates. NiO grows epitaxially on MgO at 900°C and subsequently the room deposited 80 Åthick Co films have a fcc crystal structure in epitaxy with the oxide underlayer. These samples were warmed up to 300° C and then zero-field or field cooled through the NiO Néel temperature (a 300 Oe magnetic field was applied along the [100] or the [110] MgO axis). Magnetic hysteresis loops were obtained by magneto-optical Kerr effect, the magnetic field being oriented in the plane of the substrate for various angles α with respect to the [100] direction. The usually expected behavior for such experiments is a smooth angular α dependence of the exchange bias HE close to a cosine with only one sign change over 180°. The high crystallographic coherence of our NiO/Co bilayers induces a very unusual oscillatory HE (α) dependence with several sign changes according to the NiO axis field application. Despite of the Co magnetization switching mechanism which is not a pure coherent rotation, we propose a Stoner-Wohlfhart model including four fold anisotropy and unidirectional exchange anisotropy giving a realistic description of these typical magnetic properties.

Superparamagnetic Behavior of Granular Co-C Films Consisting of Nanocrystalline Cobalt Encapsulated in Carbon

2000 ◽  
Vol 614 ◽  
Author(s):  
Hao Wang ◽  
S.P. Wong ◽  
W.Y. Cheung ◽  
N. Ke ◽  
M.F. Chiah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Magnetic Measurements ◽  
Magnetic Hysteresis ◽  
Blocking Temperature ◽  
Vacuum Arc ◽  
Zero Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy

ABSTRACTNanocomposite Co-C thin films of about 15 nm thick were prepared by pulsed filtered vacuum arc deposition. The films were characterized by x-ray photoelectron spectroscopy, non-Rutherford backscattering spectrometry, x-ray diffraction, magnetic force microscopy and magnetic measurements. The as-deposited films were amorphous. After annealing at 350°C for one hour in vacuum (< 10−3 Pa), the films were found to consist of nanocrystalline Co grains encapsulated in carbon. The superparamagnetism of the annealed Co36C64 film was demonstrated by the measurement of DC susceptibility and magnetic hysteresis using a SQUID magnetometer. The superparamagnetic relaxation blocking temperature was marked to be about 12K by the peak of the zero-field-cooled magnetization under a field of 100 Oe. The magnetic properties of these annealed granular Co-C films transform from superparamagnetism to ferromagnetism when the Co concentration increases.

Enhanced ferroelectricity and ferromagnetism in La1−xBixCrO3 by Bi3+ substitution

2007 ◽  
Vol 22 (8) ◽  
pp. 2081-2086 ◽  
Author(s):  
H-Y. Guo ◽  
J.I.L. Chen ◽  
Z-G. Ye ◽  
A.S. Arrott
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Quantum Interference ◽  
Remanent Polarization ◽  
Magnetic Hysteresis ◽  
Zero Field ◽  
Ferroelectric Hysteresis ◽  
Different Origins ◽  
Zero Field Cooling ◽  
Field Cooling

The ferroelectric and magnetic properties of the perovskite solid solution, (1 − x)LaCrO3–xBiCrO3, have been investigated. While pure LaCrO3 does not show ferroelectric hysteresis even at 77 K, the solid solution of La1−xBixCrO3 with x = 0.1, 0.2, 0.3, and 0.35 displays ferroelectric hysteresis, with the remanent polarization increasing with the increase of the Bi3+ content. Using a superconducting quantum interference device, the magnetization was measured versus temperature under field cooling (FC) and zero field cooling (ZFC) conditions. Magnetic hysteresis has been found in La1−xBixCrO3 (0.1 ⩽ x ⩽ 0.3) below the Néel temperature, TN. With the increase of Bi3+ content, TN decreases, while the magnetization below TN is enhanced. While the ferroelectric and magnetic properties could be due to different origins, the Bi substitution results in both ferroelectric and magnetic enhancements in the (1 − x)LaCrO3–xBiCrO3 solid solutions.

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