Nickel Nanocomposite Thin Films

2001 ◽  
Vol 703 ◽  
Author(s):  
Honghui Zhou ◽  
A. Kvit ◽  
D. Kumar ◽  
J. Narayan
Keyword(s):  
Quantum Interference ◽  
Magnetic Measurements ◽  
Magnetic Moments ◽  
Deposition Process ◽  
Blocking Temperature ◽  
Ni Nanoparticles ◽  
Epitaxial Relationship ◽  
Transmission Electron ◽  
Nanocomposite Thin Films ◽  
Matrix Layer

ABSTRACTNickel was deposited on epitaxial TiN matrix layer grown on Si (100) substrate by pulsed laser deposition process (PLD). Transmission electron microscopy (TEM) study shows that nanoparticles formed are single crystals with two kinds of epitaxial relationship with respect to matrix TiN. One is cube on cube, where (200) Ni // (200) TiN // (200) Si and (022) Ni // (022) TiN // (022) Si. The particles grown in this orientation have a trapezoidal morphology in [011] projection. The other involves a 90 ° rotation with respect to [011] direction of TiN matrix (zone axis), where (022) Ni // (200) TiN // (200) Si and (200) Ni // (022) TiN // (022) Si. The particles grown in this rotated orientation have a triangular morphology in [011] projection and a smaller lattice constant compared with that of pure nickel. The possible mechanism of forming these two epitaxial orientations is discussed. Superconducting quantum interference device (SQUID) magnetometer was used for magnetic measurements. In order to investigate the effect of texturing on magnetic properties of nanoparticles, results were compared with those obtained from Ni nanoparticles grown on amorphous Al2O3 matrix layer in previous research. It was found that both blocking temperature and coercivity of Ni nanoparticles grown on epitaxial TiN matrix are significantly higher than that of Ni grown on amorphous Al2O3. The higher value of coercivity is possibly associated with the stronger tendency of crystallographically oriented particles to retain their magnetic moments in the presence of reversing magnetic field.

Formation and Characterization of Single Crystal Ni2MnGa Thin Films

1999 ◽  
Vol 604 ◽  
Author(s):  
J. W. Dong ◽  
L. C. Chen ◽  
S. Mckernan ◽  
J. Q. Xie ◽  
M. T. Figus ◽  
...  
Keyword(s):  
Single Crystal ◽  
Quantum Interference ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
Molecular Beam Epitaxial ◽  
Transmission Electron ◽  
Molecular Beam Epitaxial Growth ◽  
Relationship Of

AbstractIn this paper, molecular beam epitaxial growth of Ni2MnGa single crystal layers on GaAs (001) using a NiGa interlayer is reported. X-ray diffraction and transmission electron microscopy confirmed an epitaxial relationship of Ni2MnGa [100]“010] // GaAs [100] [010] and a tetragonal structure of the film (a = b = 5.79 Å, c = 6.07 Å). Magnetic measurements using vibrating sample and superconducting quantum interference device magnetometers revealed an in-plane magnetization of ∼200 emu/cm3at room temperature and a Curie temperature of ∼350 K. The martensitic phase transformation was observed to occur at ∼250 K

Synthesis and Structural Characterization of Ferromagnetic Au/Co Nanoparticles

2014 ◽  
Vol 1708 ◽  
Author(s):  
Nabraj Bhattarai ◽  
Subarna Khanal ◽  
Daniel Bahena ◽  
Robert L. Whetten ◽  
Miguel Jose-Yacaman
Keyword(s):  
Quantum Interference ◽  
Magnetic Measurements ◽  
Ferromagnetic Behavior ◽  
Contrast Imaging ◽  
Uniform Size ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Co Nanoparticles ◽  
Z Contrast

ABSTRACTThe synthesis of bimetallic magnetic nanoparticles is very challenging because of the agglomeration and non-uniform size. In this paper, we present the synthesis of monodispersed 3-5 nm sized thiolated bimetallic alloyed Au/Co nanoparticles with decahedral and icosahedral shape, their characterization using Cs-corrected scanning transmission electron microscopy (STEM) and magnetic measurements using superconducting quantum interference device (SQUID) magnetometer. The Z-contrast imaging and energy dispersive X-ray spectroscopy (EDS) mapping showed an inhomogeneous alloying with minor segregation between Au and Co at nanoscale and the SQUID measurement exhibited the ferromagnetic behavior.

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.

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.

Tunable Magnetic Properties in Metal Ceramic Composite Thin Films

2001 ◽  
Vol 676 ◽  
Author(s):  
D. Kumar ◽  
J. Narayan ◽  
A. K. Sharma ◽  
A. Kvit ◽  
C. Jin ◽  
...  
Keyword(s):  
Thin Films ◽  
Quantum Interference ◽  
Ceramic Composite ◽  
Blocking Temperature ◽  
Magnetic Data ◽  
Superconducting Quantum Interference Device ◽  
Interface Control ◽  
Transmission Electron ◽  
Metal Ceramic ◽  
Crystalline Alumina

ABSTRACTWe have developed a novel thin film processing method based upon pulsed laser deposition to process nanocrystalline magnetic materials with accurate size and interface control. Using this method, single domain nanocrystalline Fe and Ni particles in 5-10 nm size range embedded in amorphous as well as crystalline alumina have been produced. Magnetization measurements of these layered thin films as function of field and temperature were carried out using a superconducting quantum interference device magnetometer. Hysteresis below blocking temperature have been found to be consistent with the Stoner-Wohlfarth type behavior. The size of Fe and Ni nanodots measured using transmission electron microscopy and calculated using magnetic data are in excellent agreement with each other.

Design of Iron Oxide/Silica/Alginate HYbrid MAgnetic Carriers (HYMAC)

2007 ◽  
Vol 7 (12) ◽  
pp. 4649-4654 ◽  
Author(s):  
Michel Boissière ◽  
Joachim Allouche ◽  
Roberta Brayner ◽  
Corinne Chanéac ◽  
Jacques Livage ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Spray Drying ◽  
Magnetic Measurements ◽  
Polymer Network ◽  
Blocking Temperature ◽  
X Ray ◽  
Silica Nanocomposites ◽  
Magnetic Carriers ◽  
Transmission Electron ◽  
Surface Iron

A large number of natural and synthetic polymers have already been evaluated for the design of nanomaterials incorporating magnetic nanoparticles for biomedical applications. The possibility to use hybrid (bio)-organic/inorganic nano-carriers have been much less studied. Here we describe the design of Hybrid MAgnetic Carriers (HYMAC) consisting of alginate/silica nanocomposites incorporating magnetite nanoparticles, based on a spray-drying approach. Transmission electron microscopy and X-ray energy dispersive spectrometry confirm the successful incorporation of magnetic colloids within homogeneous hybrid capsules. X-ray diffraction data suggest that surface iron ions are partially desorbed by the spray-drying process, leading to the formation of lepidocrocite and of an iron silicate phase. Magnetic measurements show that the resulting nanocomposites exhibit a superparamagnetic behaviour with a blocking temperature close to 225 K. Comparison with un-silicified capsules indicate that the mineral phase enhances the thermal stability of the polymer network and do not modify of the amount of incorporated iron oxide nanoparticles. Moreover, evaluation of nanocomposite up-take by fibroblasts indicates their possible internalization. A selective intracellular alginate degradation is observed, suggesting that these HYMAC nanomaterials may exhibit interesting properties for the design of drug delivery devices.

Silica Encapsulated Ni Nanoparticles: Variation of Optical and Magnetic Properties with Particle Size

2007 ◽  
Vol 7 (12) ◽  
pp. 4447-4455 ◽  
Author(s):  
Soumen Das ◽  
Subhendu K. Panda ◽  
Prithiwish Nandi ◽  
Subhadra Chaudhuri ◽  
Abhishek Pandey ◽  
...  
Keyword(s):  
Sol Gel ◽  
Particle Diameter ◽  
Blocking Temperature ◽  
Zero Field ◽  
Ni Nanoparticles ◽  
Ni Content ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
The Matrix ◽  
Magnetic Filed

Ni nanoparticles embedded in SiO2 matrix were prepared by sol–gel process. The molar percentages of Ni were varied from 2 to 20% of total SiO2 present in the matrix. Transmission electron microscope (TEM) images revealed that particle sizes varied from 8.0–15.7 nm at an annealing temperature of 773 K with variation of concentration. The optical absorption spectra revealed that the surface plasmon resonance (SPR) peak in the UV region of the spectrum shifted with the particle diameter (D) from that at 247.3 nm for D = 8.0 nm to 250.7 nm for D = 15.7 nm. In hysteresis loop measurements the magnetizations (M) of the nanocomposites also increased with higher Ni content in the matrix and did not saturate in the measuring limit of the magnetic filed (H) of 4 KOe. The anhysteric curves for different samples were analyzed with the law of approach to saturation (LAS). The zero field cooled (ZFC) and field cooled (FC) magnetization measurements at 50 Oe showed increasing broadening of the ZFC curve with the higher Ni content. To calculate the average blocking temperature (<TB>) a distribution of the blocking temperatures (TB) was assumed to initiate theoretical fittings and it was found to be increasing with the Ni concentration in the matrix.

Effect of Distribution of Functionalized Magnetic Nanoparticles on Ferrogel Actuation

2010 ◽  
Author(s):  
Kamlesh J. Suthar ◽  
Muralidhar K. Ghantasala ◽  
Derrick C. Mancini ◽  
Joseph E. Mowat ◽  
Jan Ilavsky
Keyword(s):  
Magnetic Field ◽  
Quantum Interference ◽  
Particle Distribution ◽  
Magnetic Moments ◽  
Crosslinking Density ◽  
Magnetic Characteristics ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Functionalized Magnetic Nanoparticles ◽  
Set Up

The ferrogels elongate, contract, and deflect in response to an applied magnetic field. In order to study its response to magnetic fields, ferrogels were prepared using meghamite (Fe304) nanoparticles (size ∼ 10–25 nm) using the hydrogel based on N-isopropylacrylamide (NIPAm). The particle distribution is determined for different cross-linking density of the gel in the range of 2% to 8%. The ferrogels were analyzed using ultra small angle x-ray scattering (USAXS) and the particle distribution were compared with direct imaging of the samples using transmission electron microscopy. The uniformity of the distribution of the particles for different samples prepared was determined using USAXS. Magnetic characteristics of the ferrogel were determined using a direct current superconducting quantum interference device (DC-Squid). The magnetic moments of the polyvinylpyrrolidone (PVP) coated Fe3O4 nanoparticles based ferrogel are reduced from 2.5 – 0.4 emu/g, as the particle concentration is decreased from 8.75 to 1.25%. Subsequently, the deflection and strain also reduced under static magnetic field. These studies showed that a maximum deflection of 20% and strain of 10% to its original value could be achieved by varying the particle size and/or distribution. The crosslinking ratio of the polymer was varied from 1.2 – 8%. The deflection and elongation characteristics were studied using a custom-built electromagnetic set-up with a pole gap of 10 mm with magnetic field strength up to 2500 Gauss. However, the maximum strain reduces as the crosslinking density increases. This study clearly shows the dependence of the deflection and strain on the functionalization material coated on the particle. Details of the results of our experiments are presented in this paper.

scholarly journals Magnetic Properties and AC Losses in AFe2O4(A = Mn, Co, Ni, Zn) Nanoparticles Synthesized from Nonaqueous Solution

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Oleksandr Yelenich ◽  
Sergii Solopan ◽  
Taras Kolodiazhnyi ◽  
Yuliya Tykhonenko ◽  
Alexandr Tovstolytkin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Measurements ◽  
Spinel Ferrite ◽  
Blocking Temperature ◽  
Ac Losses ◽  
X Ray Diffraction ◽  
Average Magnetic Moment ◽  
Heating Efficiency ◽  
Cobalt Nickel ◽  
Transmission Electron

Nanosized particles of AFe2O4(A = Mn, Co, Ni, or Zn) spinel ferrites were synthesized by coprecipitation from nonaqueous solutions using nitrate salts as starting reagents. The particles were characterized by X-ray diffraction, transmission electron microscopy, and magnetic measurements. Quasistatic magnetic measurements show superparamagnetic behavior with blocking temperature below room temperature for cobalt, nickel, and zinc spinel ferrite nanoparticles. Characteristic magnetic parameters of the particles including average magnetic moment of an individual nanoparticle and blocking temperature have been determined. The specific loss power which is released on the exposure of an ensemble of synthesized particles to a magnetic field is calculated and measured experimentally. It is shown that among all nanoferrites under study, the ZnFe2O4nanoparticles demonstrate the highest heating efficiency in AC magnetic fields. The key parameters responsible for the heating efficiency in AC magnetic field have been determined. The directions to enhance the SLP value have been outlined.

Controlled Growth of Iron Oxide Nanoparticles in the Aqueous Microdroplets

2008 ◽  
Vol 8 (9) ◽  
pp. 4574-4578
Author(s):  
Bong-Sik Jeon ◽  
Seung-Jun Lee ◽  
Jong-Duk Kim
Keyword(s):  
Particle Size ◽  
Quantum Interference ◽  
Average Diameter ◽  
Anisotropy Constant ◽  
Blocking Temperature ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Positive Ions ◽  
Transmission Electron ◽  
Average Size

Magnetite nanoparticles were synthesized by chemical coprecipitation of ferric and ferrous aqueous solutions via regulation of the microenvironment at ambient conditions. Nanocrystals having an average diameter of 6 to 12 nm were obtained by picoliter droplets, whereas only 9 nm diameter nanocrystals were prepared by microliter droplets. The size of the nanocrystals was controlled by a precise balance of reactions of hydroxide ions with positive ions at the surface layer and inner layers of the droplets. The crystal structure and average size were analyzed by X-ray diffraction pattern and transmission electron microscope images. The field dependence and temperature dependence on magnetization measured by a superconducting quantum interference device demonstrate that the as-synthesized particles are superparamagnetic at room temperature and have a size-dependent magnetic property. The anisotropy constant calculated by the blocking temperature and particle size was found to decrease with increasing particle size.

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