AC Magnetic Susceptibility Study in Co/Au Nanoparticles

2015 ◽  
Vol 233-234 ◽  
pp. 497-500 ◽  
Author(s):  
Pavol Hrubovčák ◽  
Adriana Zeleňáková ◽  
Vladimír Zeleňák ◽  
Jana Michalíková
Keyword(s):  
Magnetic Susceptibility ◽  
Relaxation Process ◽  
Au Nanoparticles ◽  
Theoretical Models ◽  
Particle Interactions ◽  
Ac Magnetic Susceptibility ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Susceptibility Study ◽  
Average Size

In this work we report the study of magnetic relaxation process presented in the bimetallic Co/Au nanoparticles prepared utilizing the reverse micelle method. Structural analysis of the system using synchrotron X-ray diffraction and transmission electron microscopy documented individual nanocrystalline particles of average size about 7 nm. Magnetic properties of the particles were examined by ac magnetic susceptibility measurements at temperature range 2 – 300 K at different frequencies of magnetic field. The relaxation process was revealed at temperature about 6 K. Application of several theoretical models on experimental data of magnetic susceptibility confirmed strong inter-particle interactions and novel superspin glass state in the nanoparticle system at low temperatures.

Synthesis of Co@Au Core-Shell Nanoparticles in Non-Aqueous Solution and their Characterization

2004 ◽  
Vol 818 ◽  
Author(s):  
Zhihui Ban ◽  
C. J. O'Connor
Keyword(s):  
Aqueous Solution ◽  
Quantum Interference ◽  
Au Nanoparticles ◽  
Magnetic Measurements ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Average Size ◽  
Core Shell Nanoparticles

AbstractA homogeneous non-aqueous solution reactions method has been developed to prepare gold-coated cobalt (Co@Au) nanoparticles. After the sample was washed with 8% HCl, XRD (X-Ray Diffraction), TEM (transmission electron microscopy), and magnetic measurements SQUID (Superconducting Quantum Interference Device) are utilized to characterize the nanocomposites. XRD shows the pattern of sample, which is responding to gold and cobalt, no cobalt oxide was found. TEM results show that the average size of Co@Au nanoparticles is about 10 nm and we can find core-shell structure of the sample. SQUID results show that the particles are ferromagnetic materials at 300K. So the gold- coated cobalt nanoparticles (Co@Au) can be successfully prepared by the homogeneous nonaqueous approach. This kind of core-shell materials is stable in acid condition, which would give many opportunities for bio- application.

The effect of silver concentration and calcination temperature on structural and optical properties of ZnO:Ag nanoparticles

2015 ◽  
Vol 29 (01) ◽  
pp. 1450254 ◽  
Author(s):  
M. Shayani Rad ◽  
A. Kompany ◽  
A. Khorsand Zak ◽  
M. E. Abrishami
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Visible Emission ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Zno Nps ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size

Pure and silver added zinc oxide nanoparticles ( ZnO -NPs and ZnO : Ag -NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500°C, 700°C, 900°C except 1100°C, in addition to ZnO . TEM images indicated that the average size of ZnO : Ag -NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.

TIN ADDITION TO THE (Bi, Pb) 2223 SYSTEM

1994 ◽  
Vol 08 (19) ◽  
pp. 1175-1183 ◽  
Author(s):  
G. RAVI CHANDRA ◽  
B. GOPALA KRISHNA ◽  
S. V. SURYANARAYANA ◽  
T. S. N. MURTHY
Keyword(s):  
Heat Treatment ◽  
Magnetic Susceptibility ◽  
Electrical Resistance ◽  
Volume Fraction ◽  
Ac Magnetic Susceptibility ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
X Ray

The effect of the addition of Sn on the superconducting properties of the Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O y system as functions of Sn concentration and heat treatment has been studied by dc electrical resistance, ac magnetic susceptibility, and X-ray diffraction. Tin addition suppresses the volume fraction of the high T c phase. Samples with Sn > 0.1 show metallic behavior up to LNT. The formation of the Ca 2 PbO 4 phase is promoted by Sn. This depletes the amount of Pb and Ca necessary for the formation of the 2223 phase, thus reducing the volume fraction of the 2223 phase. It is possible that at least a small fraction of tin substitutes some of the cationic sites of the starting composition. The results of the different measurements are presented.

scholarly journals Improvement of superconducting parameters of Bi1.6Pb0.4Sr 2Ca 2Cu 3O10+ δ added with Au nanoparticles

2018 ◽  
Vol 16 (38) ◽  
Author(s):  
Amal K. Jassim
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Au Nanoparticles ◽  
Ac Magnetic Susceptibility ◽  
Critical Temperatures ◽  
Magnetization Measurements ◽  
Dc Electrical Resistivity

Samples of Bi1.6Pb0.4Sr2Ca2Cu3O10+δ superconductor were prepared by solid-state reaction method to study the effects of gold nanoparticles addition to the superconducting system, Nano-Au was introduced by small weight percentages (0.25, 0.50, 0.75, 1.0, and 1.25 weight %). Phase identification and microstructuralcharacterization of the samples were investigated using XRD and SEM. Moreover, DC electrical resistivity as a function of the temperature, critical current density Jc, AC magnetic susceptibility, and DC magnetization measurements were carried to evaluate the relative performance of samples. x-ray diffraction analysis showed that both (Bi,Pb)-2223 and Bi-2212 phases coexist in the samples having an orthorhombic crystal structure. Both the onset critical temperatures Tc (onset) and zero electrical resistivity critical temperatures Tc (R=0) of the samples were determined from the DC electrical resistivity measurements. An improvement of the superconducting transition temperature of 6.36 % was obtained with increasing Au nanoparticles to x = 1.25 wt.%, while the critical current density is improved by 220 %. AC magnetic susceptibility measurement showed that the diamagnetic fraction and intergranular coupling of the x = 1.25 wt.% sample are greater than those of the others. The variation of magnetization with temperature (M-T curve) of the samples was measured by cooling the sample in zero fields (ZFC) and an applied field of 10 Oe (FC). The results of AC magnetic susceptibility and DC magnetization measurements were in good agreement with DC electrical resistivity measurement.

scholarly journals Formation of ZnO/Zn0.5Cd0.5Se Alloy Quantum Dots in the Presence of High Oleylamine Contents

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 999
Author(s):  
Yi-An Chen ◽  
Kuo-Hsien Chou ◽  
Yi-Yang Kuo ◽  
Cheng-Ye Wu ◽  
Po-Wen Hsiao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Particle Size ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Transmission Electron ◽  
Average Size ◽  
Alloy Quantum Dots ◽  
First Time

To the best of our knowledge, this report presents, for the first time, the schematic of the possible chemical reaction for a one-pot synthesis of Zn0.5Cd0.5Se alloy quantum dots (QDs) in the presence of low/high oleylamine (OLA) contents. For high OLA contents, high-resolution transmission electron microscopy (HRTEM) results showed that the average size of Zn0.5Cd0.5Se increases significantly from 4 to 9 nm with an increasing OLA content from 4 to 10 mL. First, [Zn(OAc)2]–OLA complex can be formed by a reaction between Zn(OAc)2 and OLA. Then, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) data confirmed that ZnO is formed by thermal decomposition of the [Zn(OAc)2]–OLA complex. The results indicated that ZnO grew on the Zn0.5Cd0.5Se surface, thus increasing the particle size. For low OLA contents, HRTEM images were used to estimate the average sizes of the Zn0.5Cd0.5Se alloy QDs, which were approximately 8, 6, and 4 nm with OLA loadings of 0, 2, and 4 mL, respectively. We found that Zn(OAc)2 and OLA could form a [Zn(OAc)2]–OLA complex, which inhibited the growth of the Zn0.5Cd0.5Se alloy QDs, due to the decreasing reaction between Zn(oleic acid)2 and Se2−, which led to a decrease in particle size.

Shape control of silver selenide nanoparticles using green capping molecules

2017 ◽  
Vol 6 (2) ◽  
Author(s):  
Nokwethemba Precious Sibiya ◽  
Makwena Justice Moloto
Keyword(s):  
Shape Control ◽  
Orthorhombic Phase ◽  
Silver Selenide ◽  
Capping Agent ◽  
X Ray Diffraction ◽  
Synthesis Of Nanoparticles ◽  
Size And Shape ◽  
Transmission Electron ◽  
Different Shapes ◽  
Average Size

AbstractEmploying a capping agent during the synthesis of nanoparticles has been reported to play a role in controlling size and shape of the nanoparticles. Due to this reason, this study reports the synthesis of silver selenide nanoparticles using different environmentally friendly capping agents (green tea, glucose, ascorbic acid and chitosan) in order to investigate their effect on the size and shape of the nanoparticles. Transmission electron microscopy (TEM) results showed that the nanoparticles have different shapes (rods, spheres and cubes) with an average size of 8–96 nm depending on the capping agent used. Fourier transformer infrared (FTIR) spectroscopy confirmed that the capping of nanoparticles was successful, while X-ray diffraction (XRD) showed that the nanoparticles have an orthorhombic phase.

Structural Characterization of Co70-xNixGa30 Ferromagnetic Shape Memory Alloys

2008 ◽  
Vol 52 ◽  
pp. 103-108 ◽  
Author(s):  
Sidananda Sarma ◽  
A. Srinivasan
Keyword(s):  
Magnetic Susceptibility ◽  
Shape Memory ◽  
Room Temperature ◽  
Structural Parameters ◽  
Ac Magnetic Susceptibility ◽  
X Ray Diffraction ◽  
Ferromagnetic Shape Memory Alloys ◽  
Two Phase ◽  
X Ray ◽  
Ferromagnetic Shape Memory

Polycrystalline ingots of Co70–xNixGa30 (20 ≤ x ≤ 26) ferromagnetic shape memory alloy (FSMA) were prepared by arc melting elemental powders followed by homogenization at 1230 °C for 24 hrs and quenching in liquid nitrogen. Room temperature X-Ray diffraction (XRD) patterns of as-quenched samples exhibited single-phase tetragonal structure for alloy compositions with x = 21 to 26, and a two-phase structure (cubic A2-phase along with weak tetragonal phase) for the alloy with x = 20. Rietveld refinement was performed on the X-ray diffraction patterns to obtain the refined structural parameters. Differential Scanning Calorimeter (DSC) curves recorded from 30 °C to 250 °C revealed martensite-austenite and austenite-martensite transformations in all alloys except the alloy with composition x = 20. Low temperature ac magnetic susceptibility measurements confirmed the existence of martensitic transformations in the alloy with x = 20. The structural transformation temperatures show a linear variation with e/a ratio. All the alloys were ferromagnetic at room temperature. Curie temperature was determined using a high temperature ac magnetic susceptibility measurement set-up.

Synthesis and Characterization of Cu2FeSnS4 Semiconductor Nanocrystals with Zincblende Structure

2012 ◽  
Vol 512-515 ◽  
pp. 2019-2022 ◽  
Author(s):  
Xiao Lu Liang ◽  
Xian Hua Wei
Keyword(s):  
Random Distribution ◽  
Semiconductor Nanocrystals ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Nir Absorption ◽  
Average Size

Cu2FeSnS4semiconductor nanocrystals with zincblende structure have been successfully synthesized by a hot-injection approach. Cu+, Fe2+, and Sn4+cations have a random distribution in the zincblende unit cell, and the occupancy possibilities are 1/2, 1/4 and 1/4, respectively. Those nanocrystals were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive spectroscopy (EDS), and UV-Vis-NIR absorption spectroscopy. The Cu2FeSnS4 nanocrystals have an average size of 7.5 nm and a band gap of 0.92 eV.

Structure and Optical Properties of ZnO and ZnO2 Nanoparticles

2019 ◽  
Vol 56 ◽  
pp. 49-62 ◽  
Author(s):  
Javier Eliel Morales-Mendoza ◽  
Francisco Paraguay-Delgado ◽  
J.A. Duarte Moller ◽  
Guillermo Herrera-Pérez ◽  
Nicolaza Pariona
Keyword(s):  
Heat Treatment ◽  
Band Edge Emission ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Colloidal Method ◽  
Zinc Peroxide ◽  
Average Size ◽  
Thermal Stability Of ◽  
Raman And Ir Spectroscopy

Zinc oxide (ZnO) and Zinc peroxide (ZnO2) nanoparticles were synthesized by colloidal method at low temperature. The thermal stability of ZnO2was studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-Ray diffraction (XRD). The crystalline structure and phase change from ZnO2to ZnO by heat treatment was studied in detail. Morphology and particle size was examined using Transmission Electron Microscopy (TEM), for as synthesized ZnO and ZnO2the shape of particles were cuasi-spherical for both materials with average size of 10±2.2 nm and 2.5±0.4 nm, respectively; The crystal size for ZnO obtained by heat treatment was 8±2.2 nm. Electron density contours show the chemical bond type ionic and covalent for ZnO and ZnO2. The vibrational properties were analyzed by Raman and IR spectroscopy. Band gap values were obtained from ultraviolet-visible (UV-Vis) absorbance spectrum. Photoluminescence (PL) spectrum for ZnO shows two emission edges located at 445 and 492 nm and in the case of ZnO2presents one edge at 364 nm originated from the band edge emission. The optical spectra present a hypsochromic shift, compared with some reported in the literature.

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