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.

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.

Microstructural Studies of Ferroelectric Bi2VO5.5 Thin Films With LaNiO3 Electrodes

1994 ◽  
Vol 341 ◽  
Author(s):  
D. Prasad Beesabathina ◽  
L. Salmanca-Riba ◽  
M. S. Hegde ◽  
K. M. Satyalakshmi ◽  
K. V. R. Prasad ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Direction ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Transmission Electron ◽  
Lattice Images ◽  
Relationship Of ◽  
Microstructural Studies

AbstractThin films of Bi2VO5.5 (BVO), a vanadium analog of the n = I member of the Aurivillius family, have been prepared by pulsed laser deposition. The BVO films grow along the [001] direction on LaNiO3(LNO) and YBa2Cu3O7 (YBCO) electrode buffer layers on LaA- IO3(LAO) substrates as obtained from X-ray diffraction studies. The microstructure of the films and of the interfaces within the film and between the film and the substrate were characterized using transmission electron microscopy. The in-plane epitaxial relationship of the rhombohedral LNO on perovskite LAO was [100] LNO // [100] LAO and [001] LNO // [001] LAO. High resolution lattice images showed a sharp interface between LNO and LAO. However, the LNO film is twinned with a preferred orientation along the growth direction. The BVO layer is single crystalline on both LNO/LAO and YBCO/LAO with the caxis parallel to the growth direction except for a thin layer of about 400 Å at the interface which is polycrystalline.

Molecular Beam Epitaxial Growth and Characterization of GaAs on Sapphire and Silicon-on-Sapphire Substrates

1988 ◽  
Vol 144 ◽  
Author(s):  
T. P. Humphreys ◽  
C. J. Miner ◽  
N. R. Parikh ◽  
K. Das ◽  
M. K. Summerville ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Optical Analysis ◽  
Molecular Beam Epitaxial ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Current Voltage ◽  
Semiconductor Contacts ◽  
Molecular Beam Epitaxial Growth

ABSTRACTEpitaxial GaAs layers have been grown by molecular beam epitaxy on (1012) sapphire and silicon-on-sapphire substrates. The grown layers were characterized by optical and transmission electron microscopy; Rutherford backscattering/channeling of 2.1 MeV He+ ions; Raman spectroscopy; Hall mobility measurements; photoluminescence spectroscopy and current-voltage measurements from metal-semiconductor contacts. The extensive microstructural, electrical and optical analysis of the GaAs layers indicates that the films deposited on silicon-on-sapphire are superior to those grown directly on (1012) sapphire substrates.

scholarly journals Solvent-Free Mechanochemical Synthesis and Characterization of Nickel Tellurides with Various Stoichiometries: NiTe, NiTe2 and Ni2Te3

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1959
Author(s):  
Matjaž Kristl ◽  
Sašo Gyergyek ◽  
Srečo D. Škapin ◽  
Janja Kristl
Keyword(s):  
Electron Microscopy ◽  
Magnetic Measurements ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Energy Consuming ◽  
Tga And Dsc

The paper reports the synthesis of nickel tellurides via a mechanochemical method from elemental precursors. NiTe, NiTe2, and Ni2Te3 were prepared by milling in stainless steel vials under nitrogen, using milling times from 1 h to 12 h. The products were characterized by powder X-ray diffraction (pXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), vibrating sample magnetometer (VSM), UV-VIS spectrometry, and thermal analysis (TGA and DSC). The products were obtained in the form of aggregates, several hundreds of nanometers in size, consisting of smaller nanosized crystallites. The magnetic measurements revealed a ferromagnetic behavior at room temperature. The band gap energies calculated using Tauc plots for NiTe, NiTe2, and Ni2Te3 were 3.59, 3.94, and 3.70 eV, respectively. The mechanochemical process has proved to be a simple and successful method for the preparation of binary nickel tellurides, avoiding the use of solvents, toxic precursors, and energy-consuming reaction conditions.

PREPARATION AND CHARACTERIZATION OF LaFeO3 THIN FILMS ON (100) SrTiO3 SUBSTRATES BY PULSED LASER DEPOSITION

2011 ◽  
Vol 01 (03) ◽  
pp. 363-367 ◽  
Author(s):  
HONG LIU ◽  
JIANGUO ZHU ◽  
DINGQUAN XIAO
Keyword(s):  
Pulsed Laser Deposition ◽  
Quantum Interference ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

A single-crystalline, crack-free, epitaxial (100)c LaFeO3 films were in situ grown by pulsed laser deposition on (100) SrTiO3 substrates. X-ray diffraction, atomic force microscopy and transmission electron microscopy reveal that the LaFeO3 films have high crystalline quality, a very smooth surface, and an atomically sharp LaFeO3/SrTiO3 interface. The magnetic properties of the LaFeO3 films were obtained by a superconducting quantum interference device magnetometry. The saturated magnetization and coercive field of LaFeO3 films are 14 emu/cm3 and 600 Oe, respectively.

Molecular Beam Epitaxial Growth and Characterization of InSb and InAsxSb1−x

1990 ◽  
Vol 198 ◽  
Author(s):  
P.N. Uppal ◽  
D.M. Gill ◽  
R. Herring
Keyword(s):  
Tensile Stress ◽  
Hall Effect ◽  
X Ray Diffraction ◽  
Si Substrates ◽  
Molecular Beam Epitaxial ◽  
Gaas On Si ◽  
Transmission Electron ◽  
Hall Effect Measurements ◽  
Molecular Beam Epitaxial Growth ◽  
Alloy Segregation

ABSTRACTLayers of InSb and InAsxSb1-x were grown on GaAs and GaAs on Si substrates and then characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) to determine the epilayer quality. Hall-effect measurements and photoluminescence (PL) were also performed. Single-crystal XRD indicated that the 5-μm InSb layers grown on GaAs had a peak full width at half maximum (FWHM) of 120 arc sec for the (004) reflection. Planar TEM of a 7-μm-thick InSb layer on GaAs(001) indicated a dislocation density of 2 x 106 cm−2 at the top of the layer. Hall effect measurements of an undoped 3.5-μm-thick InSb on semi-insulating GaAs indicated an electron density of 3.7 x 1016 cm−3 at 300K and a mobility of 45,000 cm2 / V-sec. At 77K these values were 2.7 x 1016 cm−3 and 49,200 cm2 / V-sec, respectively. The composition of the InAsxSb1-x was a function of the growth temperature and the As2/In ratio for both Sb2 and Sb4. The XRD (004) peak FWHM increased with the x value, indicating a deterioration in material quality. This may be caused by alloy segregation in InAsxSb1-x. The peak FWHM rapidly increases from x=0.1 to x=0.3 and then its value drops, indicating that the quality of the layers improved. InSb layers displayed a strong PL whereas the PL for the InAs0.5Sb0.5 layers was very weak. We also grew InSb and InAsxSb1-x layers on GaAs on Si. Optical transmission measurements on InSb indicated that the layers were under tensile stress. We believe this tensile stress could be used to lower the bandgap of InAsxSb1-x layers to provide longer cut-off wavelengths for infrared detectors.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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