scholarly journals Effect of Temperature on the Dielectric and Magnetic Properties of NiFe2O4@MgFe2O4 and ZnFe2O4@MgFe2O4 Core-shell

2021 ◽  
Author(s):  
Kheled Roumaih
Keyword(s):  
Magnetic Properties ◽  
Mutual Effect ◽  
Space Charge Polarization ◽  
Effect Of Temperature ◽  
Core Shell ◽  
Temperature Dependent ◽  
Ac Electrical Conductivity ◽  
Metallic Behavior ◽  
The Core ◽  
Alternating Electric Field

Abstract The core-shell of nanoferrites showed quite different properties rather than the nanoferrites counterpart. The nanocomposites of NiFe2O4@MgFe2O4 (NiF@MgF) and ZnFe2O4@MgFe2O4 (ZnF@MgF) are chemically stable and showed very good dielectric and magnetic properties. In this investigation, the temperature-dependent dielectric constant, dielectric loss, and ac-electrical conductivity were measured up to 650 K under different alternating electric field frequencies from 100 Hz to 8 MHz. The obtained data revealed that the mutual effect between the core and the shell samples increases the space charge polarization. Also, the samples showed the semiconducting-metallic behavior which varies between SP, CBH, and QMT models according to the temperatures and the frequencies. Furthermore, the magnetization M(T) was studied of all samples using the Faraday balance method in the temperature range 300-500K. The experimental results of M(T) exhibit good magnetic properties of the core-shell samples, particularly the sample ZnF@MgF. The novelty in this work is an unexpected behavior of ZnF@MgF which possesses magnetization higher than the pure ferrite phase (MgFe2O4), and Curie temperature (TCm) higher than the room temperature. So, the sample ZnF@MgF is a ferrimagnetic substance. Besides, the effective magnetic moment (mEff) and the Curie-Weiss constant (q) for all samples were obtained from the magnetic susceptibility c(T) protocols.

scholarly journals Effect of Temperature on the Dielectric and Magnetic Properties of NiFe2O4@MgFe2O4 and ZnFe2O4@MgFe2O4 Core-Shell

2021 ◽  
Author(s):  
Kheled Roumaih
Keyword(s):  
Magnetic Properties ◽  
Effective Magnetic Moment ◽  
Room Temperature ◽  
Mutual Effect ◽  
Space Charge Polarization ◽  
Effect Of Temperature ◽  
Core Shell ◽  
Metallic Behavior ◽  
The Core ◽  
Zn Ferrite

Abstract The core-shell NiFe2O4@MgFe2O4 (NiF@MgF) and ZnFe2O4@MgFe2O4 (ZnF@MgF) are stable nanocomposites. The experimental results showed perfect dielectric and magnetic properties different than their components. The experimental data revealed that the mutual effect between the core and the shell increases the space charge polarization. Also, the samples showed semiconducting-metallic behavior, which varies according to the temperatures and the frequencies. Furthermore, the magnetization M(T) was studied using the Faraday balance method of all samples. The obtained results of M(T) exhibit good magnetic properties of the core-shell samples, particularly the sample ZnF@MgF, where it possesses magnetization higher than the pure ferrite phase (MgFe2O4) and Curie temperature (TCm) higher than the room temperature, and this is new for Zn-ferrite. Besides, the effective magnetic moment (µEff) and the Curie-Weiss constant (θ) were obtained from the magnetic susceptibility χ(T) protocols.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

Dynamic calculations of the core/shell structured Ising-type endohedral fullerenes: The effect of core and core/shell interaction

2017 ◽  
Vol 31 (33) ◽  
pp. 1750307 ◽  
Author(s):  
Ersin Kantar
Keyword(s):  
Magnetic Properties ◽  
Magnetic Particles ◽  
Stochastic Dynamics ◽  
Mean Field Theory ◽  
Mean Field ◽  
Core Shell ◽  
Core Particle ◽  
Factors Affecting ◽  
The Core ◽  
First Order Phase

In this study, we examine by comparing the dynamic magnetic and hysteretic properties of Ising-type endohedral fullerene (EF) with various dopant magnetic particles confined within a spherical cage. The model of EF X@C[Formula: see text] with X = spin-1/2, spin-1 and spin-3/2 is proposed to study the effect of the nature of core particle on the magnetic properties. The results were obtained by mean-field theory as well as Glauber-type stochastic dynamics, and focused on the response of thermal and hysteretic behaviors of systems. The system exhibits second- and first-order phase transitions. In three different core cases, the system also exhibits type-II superconductivity behavior with a dynamic hysteresis curves of the core. All results display magnetic properties of the EF which strongly depend on the nature of core particle. Moreover, core particle and core/shell (C–S) interaction are proposed as the basic factors affecting the magnetic properties of EF system.

Formation of bismuth iron oxide based core–shell structures and their dielectric, ferroelectric and magnetic properties

2019 ◽  
Vol 7 (5) ◽  
pp. 1280-1291 ◽  
Author(s):  
Alaka Panda ◽  
R. Govindaraj ◽  
R. Mythili ◽  
G. Amarendra
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Properties ◽  
Iron Oxide ◽  
Shell Structures ◽  
Core Shell ◽  
Bismuth Iron Oxide ◽  
The Core ◽  
Shell Nanostructures ◽  
Transmission Electron

Bismuth and iron oxides subjected to ball milling followed by controlled annealing treatments showed the formation of core–shell nanostructures with Bi2Fe4O9 as the core and a shell of BiFeO3 and Bi25FeO40 phases as deduced based on the analysis of transmission electron microscopy results.

Frequency- and Temperature-Dependent Ferromagnetic Resonance of Co/CoO Core-Shell Nanoparticles

2004 ◽  
Vol 818 ◽  
Author(s):  
U. Wiedwald ◽  
J. Lindner ◽  
M. Spasova ◽  
Z. Frait ◽  
M. Hilgendorff ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Field ◽  
Core Shell ◽  
Direct Measure ◽  
Temperature Dependent ◽  
Spin Magnetic Moment ◽  
Shell Nanoparticles ◽  
The Core ◽  
G Value ◽  
Core Shell Nanoparticles

AbstractFerromagnetic Resonance experiments are used to investigate the magnetic properties of monodisperse Co/CoO core-shell nanoparticles with diameters of about 10nm. From frequency- dependent measurements at various frequencies of 9-80 GHz the g-value is determined to be 2.13 which suggests an fcc bulk-like environment of the Co atoms within the core of the particles. This result yields a direct measure of the ratio of orbital to spin magnetic moment νL/νS=0.065. Moreover, from temperature-dependent measurements of the resonance field the anisotropy energy is extracted and found much lower than the hcp bulk value.

scholarly journals Synthesis and Magnetic Properties of the Core–Shell Fe3O4/CoFe2O4 Nanoparticles

2020 ◽  
Vol 62 (2) ◽  
pp. 285-290 ◽  
Author(s):  
D. A. Balaev ◽  
S. V. Semenov ◽  
A. A. Dubrovskii ◽  
A. A. Krasikov ◽  
S. I. Popkov ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
The Core

Iron-Carbon Core-Shell Nanoparticles Obtained with Different Conditions of Synthesis

2017 ◽  
Vol 899 ◽  
pp. 221-226 ◽  
Author(s):  
M.M. Lima ◽  
J.P.Z. Gonçalves ◽  
C. Soares ◽  
Humberto Gracher Riella ◽  
S.C. Fernandes ◽  
...  
Keyword(s):  
Synthesis Method ◽  
Processing Parameters ◽  
Effect Of Temperature ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Shell Mass ◽  
The Core ◽  
Iron Precursor ◽  
Co Precipitation ◽  
Core Shell Nanoparticles

Core–shell Fe2O3@C nanoparticles are very studied due to its biocompatibility with plant and animals cells and due its special properties of chemical adsorption. Thus, the definition of an easy synthesis method of these nanoparticles is very important to the scientific studies and to future applications of these materials. For example, the properties of these nanoparticles depend of the combination between some processing parameters, as the temperature, time, chemical composition, atmosphere and others. The mass yield of the synthesis processes depend of these parameters and are important information. In this work the effect of temperature and of the concentration of the iron precursor were evaluated on the characteristics of the proposed nanoparticles. The nanostructures of Fe2O3 coated with carbon (Fe2O3@C) were synthetized by adapted co-precipitation hydrothermal rote. In 40.0 ml of distilled water was added 1.800 g of glucose, 6.006 g of urea, 0.500 g of polyethylene Glycol (PEG 1500) and different concentrations of iron nitrate Fe (NO2)3.9H2O and different temperature values were applied. The Fe2O3@C core-shell were characterized by scanning electron microscopy (SEM/FEG), Energy Dispersive Scanning (EDS) and X-ray Diffractions (XRD). Results showed that nanoparticles form clusters with different sizes that are dependent on the temperature values and Fe (NO3)3.9H2O concentration. The core-shell mass has a linear relation with the iron precursor mass and the reaction temperatures influences the microstructure of the core-shell nanoparticles.

scholarly journals Magnetic Nanoparticles: Co@SiO2, Co@Au and Co@Pt

2017 ◽  
Vol 36 (4) ◽  
pp. 01 ◽  
Author(s):  
Vagner Sargentelli ◽  
Antônio A. P. Ferreira
Keyword(s):  
Magnetic Properties ◽  
Magnetic Nanoparticles ◽  
Shell Structures ◽  
Human Organism ◽  
Core Shell ◽  
Present Moment ◽  
Metallic Oxides ◽  
The Core ◽  
Structure Changes ◽  
And Control

Nanotechnology is the understanding and control f matter at dimensions of roughly 1 – 100 nm. At the nanoscale, the properties like electrical conductivity and mechanical strength are not the same as the materials with particles in dimensions much more than 100 nm. The electronic structure changes dramatically too. Between nanomaterials, there is recently a great number of works that investing as the synthesis as the properties of the magnetic nanoparticles. The interest in these materials is due to its magnetic applications. Some of more representative magnetic materials are the metallic oxides, as some ferrites. However, the ferrites are often obtained as mixture of some oxides, which implies that the magnetic properties are not always well defined and reproducible. Thus, the researches has been turned to use of the magnetic metals, between which the cobalt. The cobalt is investigated because its high magnetic susceptility. However, this transition metal is easily oxidate in air and is toxic to human organism. For this reason, it has looked for to effect synthesis involving core – shell structures, which no to allow the oxidation of the cobalt and prevent against its toxicity. Between the shells that come being obtained it is of silica and of gold. In addition, in if treating to catalysis in a general way, the price of the cobalt and its magnetic properties are adjusted for the attainment core – shell catalysts, Cocore@Ptshell, (Co@Pt). So, the aim of this article is to present and to do an analysis of the more representative synthetic route used until the present moment to obtain the core – shell structures: Co@SiO2, Co@Au and Co@Pt.

Magnetic Properties of the Cylindrical Ising Nanowire: A Monte Carlo Simulation Study

SPIN ◽  
2017 ◽  
Vol 07 (04) ◽  
pp. 1750011 ◽  
Author(s):  
A. Jabar ◽  
R. Masrour ◽  
M. Hamedoun ◽  
A. Benyoussef
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Magnetic Properties ◽  
Crystal Field ◽  
Remanent Magnetization ◽  
Hysteresis Loops ◽  
Core Shell ◽  
Monte Carlo Simulation Study ◽  
The Core ◽  
Magnetic Nanowire

A cylindrical ferrimagnetic magnetic nanowire system of core and shell layers has been investigated using Monte Carlo simulation. Critical temperature is obtained for different values of exchange couplings at the core–shell interface, at shell–shell and core–core. The total magnetization has been the determinate for different values of crystal field. Hysteresis loop, coercive field and remanent magnetization of a core and shell layers are obtained using the Monte Carlo simulation. A number of characteristic behaviors are found, such as the occurrence of single and triple hysteresis loops for appropriate values of crystal field, temperatures values and exchange interaction values.

Magnetic and Transport Properties of Mn-Si Films Synthesized on 4H-SiC(0001) Substrates

2007 ◽  
Vol 546-549 ◽  
pp. 2167-2170 ◽  
Author(s):  
Wen Hong Wang ◽  
Fumi Yoshi Takano ◽  
Hiro Nori Ofuchi ◽  
Hiro Akinaga
Keyword(s):  
Magnetic Properties ◽  
Hall Effect ◽  
Molecular Beam ◽  
Anomalous Hall Effect ◽  
Dual Phase ◽  
Temperature Dependent ◽  
Metallic Behavior ◽  
Effect Theory ◽  
Si Films ◽  
Annealing Method

We report a systematic study of the thickness dependence of magnetic properties in carbon-incorporated Mn-Si films synthesized on a 4H-SiC(0001) homoepitaxial wafer by molecular beam epitaxy (MBE) and an annealing method. Magnetization characteristics reveal a dual-phase characteristic in films with decreasing thickness. The anomalous Hall effect has been observed in the thicker film; however, the observed temperature dependence cannot be explained by traditional anomalous Hall effect theory. The temperature dependent resisitivity indicates the film has a metallic behavior.

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