Magnetic Behaviour of FeCo/Cu Core Shell Nanoparticles

2016 ◽  
Vol 719 ◽  
pp. 3-8
Author(s):  
Angshuman Sarkar ◽  
Shilabati Hembram ◽  
Subhranshu Chatterjee ◽  
Pritam Deb ◽  
Amitava Basu Mallick
Keyword(s):  
Magnetic Properties ◽  
Annealing Temperature ◽  
Field Enhancement ◽  
Blocking Temperature ◽  
Core Shell ◽  
Line Profile Analysis ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Core Shell Nanoparticles

In the present investigation, FeCo/Cu core shell nanoparticles were prepared by coating a Cu layer over FeCo alloy nanoparticles through displacement reaction. X-ray diffraction studies confirmed the presence of FeCo and Cu phases in the sample. The grain size and lattice strains of the core shell nanostructures were evaluated from the x-ray profiles by using single line profile analysis technique. The effect of annealing temperature on the magnetic properties of the core shell nanoparticles was studied by using a vibrating sample magnetometer. The results showed that the magnetic properties improve significantly after annealing the compacts of core shell nanoparticles under a magnetic field. Enhancement in magnetization was observed in the compacts with the increase in annealing temperature. Highest saturation magnetization value of 56 emu/g was recorded in the sample which was annealed at 600°C. It has been also found that the blocking temperature of the core shell nanoparticles increases with the increase in annealing temperature.

Synthesis and Characterization of Co3O4-MnxCo3-xO4 Core-Shell Nanoparticles

MRS Advances ◽  
2018 ◽  
Vol 3 (47-48) ◽  
pp. 2899-2904
Author(s):  
Ning Bian ◽  
Robert A. Mayanovic ◽  
Mourad Benamara
Keyword(s):  
Electron Microscopy ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Blocking Temperature ◽  
Core Shell ◽  
Average Particle ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Core Shell Nanoparticles

ABSTRACTThe mixed-valence oxide Co3O4 nanoparticles, having the normal spinel structure, possess large surface area, active-site surface adsorption properties, and fast ion diffusivities. Consequently, they are widely used in lithium-ion batteries, as well as for gas sensing and heterogeneous catalysis applications. In our research, we use a two-step method to synthesize Co3O4–based core-shell nanoparticles (CSNs). Cobalt oxide (Co3O4) nanoparticles were successfully synthesized using a wet synthesis method employing KOH and cobalt acetate. Manganese was incorporated into the Co3O4 structure to synthesize inverted Co3O4@MnxCo3-xO4 CSNs using a hydrothermal method. By adjustment of pH value, we obtained two different morphologies of CSNs, one resulting in pseudo-spherical and octahedron-shaped nanoparticles (PS type) whereas the second type predominantly have a nanoplate (NP type) morphology. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS) have been performed in order to determine the morphological and structural properties of our CSNs, whereas the magnetic properties have been characterized using a superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the CSNs have the same spinel crystal structure throughout the core and shell with an average particle size of ∼19.8 nm. Our Co3O4 nanoparticles, as measured prior to CSN formation, are shown to be antiferromagnetic (AFM) in nature as shown by the magnetization data. Our SQUID data indicate that the core-shell nanoparticles have both AFM (due to the Co3O4 core) and ferrimagnetic properties (of the shell) with a coercivity field of 300 Oe and 150 Oe at 5 K for the PS and NP samples, respectively. The magnetization vs temperature data show a spin order-disorder transition at ∼33 K and a superparamagnetic blocking temperature of ∼90 K for both batches.

Dependence of Relaxation Time on the Core Size Two-Phase Nanoparticles Magnetite/Titanomagnetite

2015 ◽  
Vol 752-753 ◽  
pp. 418-421
Author(s):  
Ilia Iliushin ◽  
Leonid Afremov ◽  
Sergey Anisimov
Keyword(s):  
Relaxation Time ◽  
Blocking Temperature ◽  
Exchange Constant ◽  
Core Shell ◽  
Core Size ◽  
Shell Nanoparticles ◽  
Two Phase ◽  
The Core ◽  
Core Shell Nanoparticles ◽  
Model Nanoparticles

In this paper, depending of the blocking temperature on magnetite core size for core/shell nanoparticles has been carried out using our theoretical model. Nanoparticles has size of 100nm, and magnetite core increases from 0nm to 100nm. Systems were studied with different values of exchange constant. The data obtained indicate that exchange constant increases the blocking temperature. However, the sign of the constant does not matter.

scholarly journals Luminescence Nanothermometry Based on Pr3+ : LaF3 Single Core and Pr3+ : LaF3/LaF3 Core/Shell Nanoparticles

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
M. S. Pudovkin ◽  
D. A. Koryakovtseva ◽  
E. V. Lukinova ◽  
S. L. Korableva ◽  
R. Sh. Khusnutdinova ◽  
...  
Keyword(s):  
Coherent Scattering ◽  
Core Shell ◽  
Fluorescence Intensity Ratio ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Core Shell Nanoparticles

Core Pr3+ : LaF3 (CPr = 1%) plate-like nanoparticles (nanoplates), core/shell Pr3+ : LaF3 (CPr = 1%)/LaF3 nanoplates, core Pr3+ : LaF3 (CPr = 1%) sphere-like nanoparticles (nanospheres), and core/shell Pr3+ : LaF3 (CPr = 1%)/LaF3 nanospheres were synthesized via the coprecipitation method of synthesis. The nanoparticles (NPs) were characterized by means of transmission electron microscopy, X-ray diffraction, and optical spectroscopy. The formation of the shell was proved by detecting the increase in physical sizes, sizes of coherent scattering regions, and luminescence lifetimes of core/shell NPs comparing with single core NPs. The average physical sizes of core nanoplates, core/shell nanoplates, core nanospheres, and core/shell nanospheres were 62.2 ± 0.9, 74.7 ± 1.2, 13.8 ± 0.9 and 22.0 ± 1.2 nm, respectively. The formation of the NP shell led to increasing of effective luminescence lifetime τeff of the 3P0 state of Pr3+ ions for the core nanoplates, core/shell nanoplates, core nanospheres, and core/shell nanospheres the values of τeff were 2.3, 3.6, 3.2, and 4.7 μsec, respectively (at 300 K). The values of absolute sensitivity Sa for fluorescence intensity ratio (FIR) thermometry was 0.01 K−1 at 300 K for all the samples. The FIR sensitivity can be attributed to the fact that 3P1 and 3P0 states share their electronic populations according to the Boltzmann process. The values of Sa for lifetime thermometry for core nanoplates, core/shell nanoplates, core nanospheres, and core/shell nanospheres were (36.4 ± 3.1) · 10−4, (70.7 ± 5.9) · 10−4, (40.7 ± 2.6) · 10−4, and (68.8 ± 2.4) · 10−4 K−1, respectively.

scholarly journals Blocking Temperature of a System of Core/Shell Nanoparticles

2020 ◽  
Vol 312 ◽  
pp. 270-274
Author(s):  
Leonid Lazarevich Afremov ◽  
Sergei Anisimov ◽  
Ilia Iliushin
Keyword(s):  
Theoretical Study ◽  
Blocking Temperature ◽  
Core Shell ◽  
Magnetostatic Interaction ◽  
Shell Nanoparticles ◽  
Shell System ◽  
The Core ◽  
Core Shell Nanoparticles

A theoretical study was made of the dependence of the blocking temperature of the core/shell system of nanoparticles on the intensity of their magnetostatic interaction. It is shown that with an increase in the concentration of nanoparticles (intensity of the magnetostatic interaction), the blocking temperature increases. Moreover, the of large nanoparticles changes more significantly.

scholarly journals Synthesis, Characterization, and Optimization of Magnetoelectric BaTiO3–Iron Oxide Core–Shell Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 563 ◽  
Author(s):  
Mahmud Reaz ◽  
Ariful Haque ◽  
Kartik Ghosh
Keyword(s):  
Iron Oxide ◽  
Photoelectron Spectroscopy ◽  
Oxide Phase ◽  
Rietveld Analysis ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
X Ray ◽  
The Core ◽  
Iron Oxide Core ◽  
Core Shell Nanoparticles

Improvement of magnetic, electronic, optical, and catalytic properties in cutting-edge technologies including drug delivery, energy storage, magnetic transistor, and spintronics requires novel nanomaterials. This article discusses the unique, clean, and homogeneous physiochemical synthesis of BaTiO3/iron oxide core–shell nanoparticles with interfaces between ferroelectric and ferromagnetic materials. High-resolution transmission electron microscopy displayed the distinguished disparity between the core and shell of the synthesized nanoparticles. Elemental mapping and line scan confirmed the formation of the core–shell structure. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy detected the surface iron oxide phase as maghemite. Rietveld analysis of the X-ray diffraction data labeled the crystallinity and phase purity. This study provides a promising platform for the desirable property development of the futuristic multifunctional nanodevices.

scholarly journals Synthesis and Advanced Characterization of Polymer-Protein Core-Shell Nanoparticles

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 730
Author(s):  
Erik Sarnello ◽  
Tao Li
Keyword(s):  
Particle Size ◽  
Small Angle ◽  
Core Shell ◽  
Assembly Process ◽  
Shell Nanoparticles ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
Core Shell Nanoparticles ◽  
Ray Scattering

Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.

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