Superparamagnetism and Microstructural Properties of Carbon Encapsulated Ni nanoparticle Assemblies

2001 ◽  
Vol 676 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
Xinglong Dong ◽  
J. A. Toledo ◽  
M. J. Yacaman
Keyword(s):  
Arc Discharge ◽  
Spherical Shape ◽  
Good Evidence ◽  
Particle Radius ◽  
Blocking Temperature ◽  
Average Particle ◽  
Ni Nanoparticles ◽  
Microstructural Properties ◽  
Superparamagnetic Relaxation ◽  
Average Particle Radius

ABSTRACTCarbon encapsulated Ni nanoparticles (Ni(C)) were synthesized by modified arc-discharge reactor under methane atmosphere. The presence of carbon encapsulation is confirmed by HR-TEM imaging, and Nano-diffraction. The average particle radius is typically 10.5 nm with spherical shape. The intimate and contiguous carbon fringe around these Ni nanoparticles is good evidence for complete encapsulation by carbon shell layers.Superparamagnetic property studies were performed using SQUID magnetometer for the assemblies of Ni(C) nanoparticles. The blocking temperature (TB) is determined to around 115K at 1000Oe applied field. Above TB, the magnetization M (H, T) can be described by the classical Langevin function L using the relation, M/Ms(T=0) = coth(μH/kT)- kT/μH. The particle radius can be inferred from Langevin fit (particle moment μ) and blocking temperature theory (TB), which values are a little bigger than HR-TEM observations. It is suggested, these assemblies of carbon encapsulated Ni nanoparticles have been showed typical single-domain, field-dependent superparamagnetic relaxation properties.

Magnetic Properties of Ni Nanoparticles Embedded in Amorphous SiO2

2002 ◽  
Vol 746 ◽  
Author(s):  
Fabio C. Fonseca ◽  
Gerardo F. Goya ◽  
Renato F. Jardim ◽  
Reginaldo Muccillo ◽  
Neftalí L. V. Carreño ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Temperature Dependence ◽  
Excellent Agreement ◽  
Magnetic Moments ◽  
Magnetic Hysteresis ◽  
Blocking Temperature ◽  
Spherical Particles ◽  
Average Particle ◽  
Ni Nanoparticles ◽  
Tem Analysis

ABSTRACTA modified sol-gel technique was used to synthesize nanocomposites of Ni:SiO2 which resulted in Ni nanoparticles embedded in a SiO2 amorphous matrix. Transmission electron microscopy TEM analysis were performed to study the structure and morphology of the magnetic powders. The Ni particles were found to have a good dispersion and a controlled particle size distribution, with average particle radius of ∼ 3 nm. A detailed characterization of the magnetic properties was done through magnetization measurements M(T,H) in applied magnetic fields up to ± 7 T and for temperatures ranging from 2 to 300 K. The superparamagnetic (SPM) behavior of these metallic nanoparticles was inferred from the temperature dependence of the magnetization. The blocking temperature TB, as low as 20 K, was found to be dependent on Ni concentration, increasing with increasing Ni content. The SPM behavior above the blocking temperature TB was confirmed by the collapse of M/MS vs. H/T data in universal curves. These curves were fitted to a log-normal weighted Langevin function allowing us to determine the distribution of magnetic moments. Using the fitted magnetic moments and the Ni saturation magnetization, the radii of spherical particles were determined to be close to ∼ 3 nm, in excellent agreement with TEM analysis. Also, magnetic hysteresis loops were found to be symmetric along the field axis with no shift via exchange bias, suggesting that Ni particles are free from an oxide layer. In addition, for the most diluted samples, the magnetic behavior of these Ni nanoparticles is in excellent agreement with the predictions of randomly oriented and noninteracting magnetic particles. This was confirmed by the temperature dependence of the coercivity field that obeys the relation HC(T) = HC0 [1-(T/TB)1/2] below TB with HC0 ∼ 780 Oe.

scholarly journals Морфологические и структурные особенности формирования наночастиц на основе оксида железа при вакуумно-дуговом распылении

2019 ◽  
Vol 61 (7) ◽  
pp. 1240
Author(s):  
И.В. Карпов ◽  
А.В. Ушаков ◽  
Л.Ю. Фёдоров ◽  
Е.А. Дорожкина ◽  
О.Н. Карпова ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Crystalline Phase ◽  
Room Temperature ◽  
Discharge Plasma ◽  
Arc Discharge ◽  
Average Particle Size ◽  
Ferrite Nanoparticles ◽  
Blocking Temperature ◽  
Average Particle

Ferrite nanoparticles (Fe3O4) were obtained in low-pressure arc discharge plasma. Studies have shown that the obtained nanoparticles have an average particle size of 9.4 nm, the crystalline phase of magnetite, have superparamegnets at room temperature, and a blocking temperature of 89 K. The behavior of nanoparticles in a magnetic field associated with a large specific surface is discussed.

Vacuum-arc synthesis of metal-organic framework structures based on ZrO2

2021 ◽  
pp. 30-35
Author(s):  
Igor Karpov ◽  
◽  
Anatoly Ushakov ◽  
Leonid Fedorov ◽  
Elena Goncharova ◽  
...  
Keyword(s):  
Arc Discharge ◽  
Metal Organic Framework ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Lattice Parameter ◽  
Vacuum Arc ◽  
Average Particle ◽  
Transmission Microscopy ◽  
Metal Organic ◽  
Organic Framework

The vacuum-arc synthesis of nanopowders based on zirconium oxide and metal-organic framework structures was carried out using a low-pressure arc discharge plasma. The obtained material was studied by several methods (XRF, IR, TEM, DTA). The TEM method showed that Zr-MOK is a highly agglomerated particle of an almost spherical shape. The image clearly shows the crystalline ordering of nanoparticles with a large (about 2 nm) lattice parameter. Particle sizes range from 5 to 30 nm. Average particle size 9.4 nm. XRD showed that the proportion of ZrO relative to Zr-MOK, calculated from the most intense lines of the diffractogram, is 65%. XRF results are in good agreement with IR studies. The DTA curve demonstrates a continuous exothermic process associated with a number of features of the plasma-chemical synthesis and morphology of the resulting nanoparticles, which is in full agreement with studies using transmission microscopy.

Preparation ZnO nanoparticles with Different Concentration by Laser Ablation in Liquid

2021 ◽  
Vol 39 (1B) ◽  
pp. 197-202
Author(s):  
Ghufran S. Jaber ◽  
Khawla S. Khashan ◽  
Maha J. Abbas
Keyword(s):  
Particle Size ◽  
Laser Ablation ◽  
Laser Pulse ◽  
Laser Energy ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Pulse Number ◽  
Average Particle ◽  
Zno Nps ◽  
Laser Ablation In Liquid

The effects of varying laser pulse numbers on the fabricated of ZnONPs by pulsed laser ablation in deionized water of Zn-metal are investigated. The Nd: YAG laser at energy 600mJ prepared three samples by change the laser pulse number (100, 150, and 200). The results were collected and examined using an electron scanning microscope, XRD – diffraction, and transmission electron microscope. The result revealed the colloidal spherical shape and the homogeneous composition of the ZnO NPs. The nanoparticles resulted in different concentrations and sized distributions by changing the pulse number of a laser. The average particle size and the mass concentration of particle size increase with an increasing number of laser pulses by fixed the laser energy.

scholarly journals Effect of the polymeric coating over Fe3O4 particles used for magnetic separation

2010 ◽  
Vol 8 (5) ◽  
pp. 1041-1046 ◽  
Author(s):  
Raúl Reza ◽  
Carlos Martínez Pérez ◽  
Claudia Rodríguez González ◽  
Humberto Romero ◽  
Perla García Casillas
Keyword(s):  
Particle Size ◽  
Magnetite Nanoparticles ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Polymeric Coating ◽  
Average Particle ◽  
Synthesis Conditions ◽  
Aging Conditions ◽  
Magnetite Particles ◽  
Average Size

AbstractIn this work, the synthesis of magnetite nanoparticles by two variant chemical coprecipitation methods that involve reflux and aging conditions was investigated. The influence of the synthesis conditions on particle size, morphology, magnetic properties and protein adsorption were studied. The synthesized magnetite nanoparticles showed a spherical shape with an average particle size directly influenced by the synthesis technique. Particles of average size 27 nm and 200 nm were obtained. When the coprecipitation method was used without reflux and aging, the smallest particles were obtained. Magnetite nanoparticles obtained from both methods exhibited a superparamagnetic behavior and their saturation magnetization was particle size dependent. Values of 67 and 78 emu g−1 were obtained for the 27 nm and 200 nm magnetite particles, respectively. The nanoparticles were coated with silica, aminosilane, and silica-aminosilane shell. The influence of the coating on protein absorption was studied using Bovine Serum Albumin (BSA) protein.

scholarly journals Synthesis, Characterization, and In Vitro Drug Delivery of Chitosan-Silica Hybrid Microspheres for Bone Tissue Engineering

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Niu Niu ◽  
Shu-Hua Teng ◽  
Hua-Jian Zhou ◽  
Hai-Sheng Qian
Keyword(s):  
Drug Release ◽  
Sol Gel ◽  
Particle Diameter ◽  
Spherical Shape ◽  
Average Particle ◽  
High Dispersity ◽  
Model Drug ◽  
Regular Spherical Shape

Chitosan-silica (CS-SiO2) hybrid microspheres were prepared through the combined process of sol-gel and emulsification-crosslinking. Their composition, morphology, in vitro bioactivity, and drug release behavior were investigated. The results showed that, when 20 wt% SiO2 was incorporated, the as-prepared CS-SiO2 hybrid microspheres exhibited a regular spherical shape, a high dispersity, and a uniform microstructure. Their average particle diameter was determined to be about 24.0 μm. The in situ deposited inorganic phase of the hybrid microspheres was identified as amorphous SiO2, and its actual content was determined by the TG analysis. As compared with the pure chitosan microspheres, the CS-SiO2 hybrid microspheres displayed a greatly improved in vitro bioactivity. Vancomycin hydrochloride (VH) was selected as a model drug. It was demonstrated that the CS-SiO2 hybrid microspheres presented a good capacity for both loading and sustained release of VH. Moreover, the increase of the SiO2 content efficiently slowed down the drug release rate of the CS-SiO2 hybrid microspheres.

Preparation and Particle Size Characterization of Cu Nanoparticles Prepared by Anodic Arc Plasma

2010 ◽  
Vol 92 ◽  
pp. 163-169
Author(s):  
Hong Xia Qiao ◽  
Zhi Qiang Wei ◽  
Ming Ru Zhou ◽  
Zhong Mao He
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Average Particle ◽  
Uniform Size

Copper nanoparticles were successfully prepared in large scales by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by X-ray diffraction (XRD), BET equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED). The experiment results indicate that the crystal structure of the samples is fcc structure as same as that of the bulk materials. The specific surface area is is 11 m2/g, with the particle size distribution ranging from 30 to 90 nm, the average particle size about 67nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles have uniform size, higher purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

MAGNETIC PROPERTIES OF Ni NANOPARTICLES

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4390-4394 ◽  
Author(s):  
Y. T. JEON ◽  
J. Y. MOON ◽  
G. H. LEE ◽  
J. PARK
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Magnetic Moments ◽  
Particle Diameter ◽  
Average Particle ◽  
Ni Nanoparticles ◽  
Size Dependent

We investigated the size dependent magnetic properties of Ni nanoparticles. We prepared four samples with average particle diameters of 7.0, 14.0, 16.5, and 20.0 nm. The blocking temperatures (TBs) were 40.0, 150.0, 250.0, and ~ 300.0 K for the above Ni nanoparticles, respectively. Saturation magnetization increased with increasing particle diameter due to the reduced magnetic moments of surface atoms. The coercivities at 5 K ranged from 270 and 340 Oe, whereas those at 300 K were zero due to superparamagnetism.

Scalable Production of Carbon Encapsulated Ni Nanoparticles by Water Arc Discharge: Structural and Magnetic Properties

2005 ◽  
Vol 23 ◽  
pp. 87-90 ◽  
Author(s):  
K.H. Ang ◽  
I. Alexandrou ◽  
N.D. Mathur ◽  
R. Lacerda ◽  
I.Y.Y. Bu ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Arc Discharge ◽  
Narrow Particle Size Distribution ◽  
Ni Nanoparticles ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Water Container

An electric arc discharge in de-ionised water between a solid graphite cathode and an anode made by compressing Ni and C containing powders in a mass ratio of Ni:C = 7:3 was used here to prepare carbon encapsulated Ni nanoparticles in the form of powder suspended in water. The morphology of the produced material was analysed using high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The magnetic properties of the samples were determined using a Princeton vibrating sample magnetometer (VSM). Collection of the powder produced from different depths in the water container has proved to be an effective method for obtaining samples with narrow particle size distribution. Further material purification by dry NH4 plasma etching was used to remove the amorphous carbon content of the samples. XRD and HRTEM analysis showed that the material synthesized is fcc Ni particles with mean particle size ranging from 14 to 30 nm encapsulated in 2 to 5 graphitic cages. The data suggests that the process reported has the ability to mass-produce carbon encapsulated ferromagnetic nanoparticles with desired particle size distribution, and hence with controlled size-dependent magnetic properties.

Synthesis of Ni@MWCNTs Magnetic Nanocatalysts and their Catalytic Activity towards 4-Nitrophenol Reduction

2012 ◽  
Vol 531 ◽  
pp. 358-361 ◽  
Author(s):  
Ming Mei Zhang ◽  
Qian Sun ◽  
Ji Min Xie
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Average Particle Size ◽  
Chemical Vapor ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Ni Nanoparticles ◽  
Nitrophenol Reduction ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

A well-dispersed Ni nanoparticles on multi-walled carbon nanotubes (Ni@MWCNTs) was prepared by chemical vapor deposition (CVD) method using a vacuum quartz tube furnace at the temperature of 600°C. The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed to characterize the synthesized catalyst. It shows an unfirom dispersion of Ni nanoparticles on MWCNTs with the average particle size of 8.6 nm. The as synthesized catalyst was applied in a redox reaction of 4-nitrophenol, which showed very high catalytic activity, stability and well conversion. The catalyst can be easily separated due to the magnetical performance

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