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.

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.

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.

Aromatic thiol-modulated Ag overgrowth on gold nanoparticles: tracking the thiol's position in the core–shell nanoparticles

Nanoscale ◽  
2019 ◽  
Vol 11 (37) ◽  
pp. 17471-17477 ◽  
Author(s):  
Jiaqi Chen ◽  
Dejing Meng ◽  
Hui Wang ◽  
Haiyun Li ◽  
Yinglu Ji ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Growth Process ◽  
Shell Growth ◽  
Core Shell ◽  
Internal Reference ◽  
Shell Nanoparticles ◽  
Aromatic Thiol ◽  
The Core ◽  
Spatial Trajectory ◽  
Core Shell Nanoparticles

Using DMAB as the Raman internal reference, the spatial trajectory of modulating 4-ATP molecules was tracked during the shell growth process.

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.

PREPARATION AND CHARACTERIZATION OF SURFACE-FUNCTIONALIZATION OF SILICA-COATED MAGNETITE NANOPARTICLES FOR DRUG DELIVERY

NANO ◽  
2014 ◽  
Vol 09 (04) ◽  
pp. 1450042 ◽  
Author(s):  
CONG-WANG ZHANG ◽  
CHANG-CHUN ZENG ◽  
YING XU
Keyword(s):  
Drug Delivery ◽  
Shell Structure ◽  
Drug Carrier ◽  
Point Of View ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Application Potential ◽  
Core Shell Structure ◽  
Core Shell Nanoparticles

Fe 3 O 4– SiO 2 core–shell structure nanoparticles containing magnetic properties were investigated for their potential use in drug delivery. The Fe 3 O 4– SiO 2 core–shell structure nanoparticles were successfully synthesized by a simple and convenient way. The Fe 3 O 4– SiO 2 nanoparticles showed superparamagnetic behavior, indicating a great application potential in separation technologies. From the application point of view, the prepared nanoparticles were found to act as an efficient drug carrier. Specifically, the surface of the core–shell nanoparticles was modified with amino groups by use of silane coupling agent 3-aminopropyltriethoxysilane (APTS). Doxorubicin (DOX) was successfully grafted to the surface of the core–shell nanoparticles after the decoration with the carboxyl acid groups on the surface of amino-modified core–shell structure nanoparticles. Moreover, the nanocomposite showed a good drug delivery performance in the DOX-loading efficiency and drug release experiments, confirming that the materials had a great application potential in drug delivery. It is envisioned that the prepared materials are the ideal agent for application in medical diagnosis and therapy.

Colloidal Preparation of γ-Fe2O3@Au [core@shell] Nanoparticles

2003 ◽  
Vol 774 ◽  
Author(s):  
Jiye Fang ◽  
Jibao He ◽  
Eun Young Shin ◽  
Deborah Grimm ◽  
Charles J. O'Connor ◽  
...  
Keyword(s):  
Magnetic Core ◽  
Core Shell ◽  
Medical Systems ◽  
Solution Synthesis ◽  
Organic Solution ◽  
Shell Nanoparticles ◽  
The Core ◽  
Promising Application ◽  
Core Shell Structure ◽  
Core Shell Nanoparticles

Abstractγ-Fe2O3@Au core-shell nanoparticles were prepared through a combined route, in which high temperature organic solution synthesis and colloidal microemulsion techniques were successively applied. High magnification of TEM reveals the core-shell structure. The presence of Au on the surface of as-prepared particles is also confirmed by UV-Vis absorption. The magnetic core-shell nanoparticles offer a promising application in bio- and medical systems.

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