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.

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.

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.

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 Enhanced Energy-Transfer Properties in Core-Shell Photoluminescent Nanoparticles Using Mesoporous SiO2 Intermediate Layers

2020 ◽  
Vol 58 (2) ◽  
pp. 137-144
Author(s):  
Woo Hyeong Sim ◽  
Seyun Kim ◽  
Weon Ho Shin ◽  
Hyung Mo Jeong
Keyword(s):  
Optical Properties ◽  
Energy Transfer ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Infrared Light ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Intermediate Layers ◽  
Core Shell Nanoparticles

Multi-layer core-shell nanoparticles (YVO<sub>4</sub>:Nd<sup>3+</sup>/mSiO<sub>2</sub>/SiO<sub>2</sub>) consisting of silica cores (SiO<sub>2</sub>), mesoporous silica (mSiO<sub>2</sub>) intermediate layers, and Neodymium doped rare-earth phosphor (YVO<sub>4</sub>:Nd<sup>3+</sup>) shell layers were successfully synthesized using the stepwise sol-gel method. The morphological structure and optical properties of the functional core-shell nanoparticles were characterized and evaluated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) analysis. mSiO<sub>2</sub> intermediate layers were utilized as the bridge between the core and shell materials. Their porous surfaces served to anchor the YVO<sub>4</sub>:Nd<sup>3+</sup> crystals. This prevents energy loss during the energy transfer of electrons, resulting in improved optical properties. The use of intermediate layer combinations of mSiO<sub>2</sub>/SiO<sub>2</sub> in the coreshell structure also improved cost-effectiveness, because the core is filled with cheap silica, not expensive phosphors. Even though the nanoparticles used only a thin layer of the photoluminescent shell materials, the optical properties, resulting from the energy-transfer emitting mid-infrared light, were remarkably enhanced by increasing the crystallinity of the phosphor. To demonstrate the practical use of the synthesis method, the photoluminescent properties of the core-shell nanoparticles were optimized by adjusting the annealing temperature and scaling to mass production. We believe that our efficient synthetic strategy provides a facile way of obtaining functional, cost-effective core-shell nanoparticles with improved photoluminescent properties.

scholarly journals Iron Oxide–Silica Core–Shell Nanoparticles Functionalized with Essential Oils for Antimicrobial Therapies

Antibiotics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1138
Author(s):  
Cristina Chircov ◽  
Maria-Florentina Matei ◽  
Ionela Andreea Neacșu ◽  
Bogdan Stefan Vasile ◽  
Ovidiu-Cristian Oprea ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Essential Oils ◽  
Synthesis Method ◽  
Gas Chromatography Mass Spectrometry ◽  
In Vitro Tests ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Nanostructured Systems ◽  
Core Shell Nanoparticles ◽  
The Impact

Recent years have witnessed a tremendous interest in the use of essential oils in biomedical applications due to their intrinsic antimicrobial, antioxidant, and anticancer properties. However, their low aqueous solubility and high volatility compromise their maximum potential, thus requiring the development of efficient supports for their delivery. Hence, this manuscript focuses on developing nanostructured systems based on Fe3O4@SiO2 core–shell nanoparticles and three different types of essential oils, i.e., thyme, rosemary, and basil, to overcome these limitations. Specifically, this work represents a comparative study between co-precipitation and microwave-assisted hydrothermal methods for the synthesis of Fe3O4@SiO2 core–shell nanoparticles. All magnetic samples were characterized by X-ray diffraction (XRD), gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) to study the impact of the synthesis method on the nanoparticle formation and properties, in terms of crystallinity, purity, size, morphology, stability, and magnetization. Moreover, the antimicrobial properties of the synthesized nanocomposites were assessed through in vitro tests on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. In this manner, this study demonstrated the efficiency of the core–shell nanostructured systems as potential applications in antimicrobial therapies.

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