Epitaxial growth and magnetic behavior of NiFe2O4 thin films

Thin films of NiFe2O4 were deposited on SrTiO3 (001) and Y0.15Zr0.85O2 (yttria-stabilized zirconia) (001) and (011) substrates by 90°-off-axis sputtering. Ion channeling, x-ray diffraction, and transmission electron microscopy studies reveal that films grown at 600 °C consist of ∼300 Å diameter grains separated by thin regions of highly defective or amorphous material. The development of this microstructure is attributed to the presence of rotated or displaced crystallographic domains and is comparable to that observed in other materials grown on mismatched substrates (e.g., GaAs/Si or Ba2YCu3O7/MgO). Postdeposition annealing at 1000 °C yields films that are essentially single crystal. The magnetic properties of the films are strongly affected by the structural changes; unannealed films are not magnetically saturated even in an applied field of 55 kOe, while the annealed films have properties comparable to those of bulk, single crystal NiFe2O4. Homoepitaxial films grown at 400 °C also are essentially single crystal.

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Epitaxial BaTiO3 Thin Films on Different Substrates for Optical Waveguide Applications

MRS Proceedings ◽

10.1557/proc-597-145 ◽

1999 ◽

Vol 597 ◽

Cited By ~ 5

Author(s):

M. Siegert ◽

Judit G. Lisoni ◽

C. H. Lei ◽

A. Eckau ◽

W. Zander ◽

...

Keyword(s):

Thin Films ◽

Optical Waveguides ◽

Rutherford Backscattering Spectrometry ◽

Optical Data ◽

X Ray Diffraction ◽

X Ray ◽

Force Microscopy ◽

Ion Channeling ◽

Atomic Force ◽

Transmission Electron

AbstractIn the process of developing thin film electro-optical waveguides we investigated the influence of different substrates on the optical and structural properties of epitaxial BaTiO3 thin films. These films are grown by on-axis pulsed laser deposition (PLD) on MgO(100), MgAl2O4(100), SrTiO3(100) and MgO buffered A12O3(1102) substrates. The waveguide losses and the refractive indices were measured with a prism coupling setup. The optical data are correlated to the results of Rutherford backscattering spectrometry/ion channeling (RBS/C). X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). BaTiO3 films on MgO(100) substrates show planar waveguide losses of 3 dB/cm and ridge waveguide losses of 5 dB/cm at a wavelength of 633 nm.

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Structural and Optical Property Investigations on Mg-Alloying in Epitaxial Zinc Oxide Films on Sapphire

MRS Proceedings ◽

10.1557/proc-595-f99w3.87 ◽

1999 ◽

Vol 595 ◽

Author(s):

A.K. Sharma ◽

C. Jin ◽

A. Kvit ◽

J. Narayan ◽

J.F. Muth ◽

...

Keyword(s):

Single Crystal ◽

Room Temperature ◽

X Ray Diffraction ◽

X Ray ◽

Ion Channeling ◽

Zinc Oxide Films ◽

Transmission Electron ◽

Potential Applications ◽

Post Deposition

AbstractWe have synthesized single-crystal epitaxial MgZnO films by pulsed-laser deposition. High-resolution transmission electron microscopy, X-ray diffraction and Rutherford backscattering spectroscopy/ion channeling were used to characterize the microstructure, defect content, composition and epitaxial single-crystal quality of the films. In these films with up to ∼ 34 atomic percent Mg incorporation, an intense ultraviolet band edge photoluminescence at room temperature and 77 K was observed. The highly efficient photoluminescence is indicative of the excitonic nature of the material. Transmission spectroscopy revealed that the excitonic structure of the alloys was clearly visible at room temperature. Post-deposition annealing in oxygen reduced the number of defects and improved the optical properties of the films. The potential applications of MgZnO alloys in a variety of optoelectronic devices are discussed.

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Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions

Journal of Materials Research ◽

10.1557/jmr.2010.0311 ◽

2010 ◽

Vol 25 (12) ◽

pp. 2341-2348 ◽

Cited By ~ 31

Author(s):

W. Jiang ◽

H. Wang ◽

I. Kim ◽

Y. Zhang ◽

W.J. Weber

Keyword(s):

Grain Size ◽

Single Crystal ◽

Room Temperature ◽

Ex Situ ◽

Bulk Single Crystal ◽

X Ray Diffraction ◽

X Ray ◽

Ion Channeling

Irradiation-induced amorphization in nanocrystalline and single-crystal 3C-SiC has been studied using 1 MeV Si+ ions under identical irradiation conditions at room temperature and 400 K. The disordering behavior has been characterized using in situ ion channeling and ex situ x-ray diffraction methods. The results show that, compared with single-crystal 3C-SiC, full amorphization of small 3C-SiC grains (˜3.8 nm in size) at room temperature occurs at a slightly lower dose. Grain size decreases with increasing dose until a fully amorphized state is attained. The amorphization dose increases at 400 K relative to room temperature. However, at 400 K, the amorphization dose for 2.0 nm grains is about a factor of 4 and 8 smaller than for 3.0 nm grains and bulk single-crystal 3C-SiC, respectively. The behavior is attributed to the preferential amorphization at the interface.

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Ion Beam Synthesis of Buried CoSi2 Layers in SiGe Alloys

MRS Proceedings ◽

10.1557/proc-279-875 ◽

1992 ◽

Vol 279 ◽

Author(s):

R. Jebasinski ◽

S. Mantl ◽

Chr. Dieker ◽

H. Dederichs ◽

L. Vescan ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Ion Implantation ◽

Single Crystal ◽

Rapid Thermal Annealing ◽

Ion Beam ◽

X Ray Diffraction ◽

X Ray ◽

Ion Channeling ◽

Transmission Electron

ABSTRACTSynthesis of buried, epitaxial CoSi2 layers in Si1−xGex alloys (x =0.48 and x = 0.09) by 100 and 150 keV Co+ ion implantation and subsequent rapid thermal annealing was studied by X-Ray diffraction, Rutherford backscattering spectroscopy, He ion channeling, Auger Eectron Spectroscopy and Transmission Electron Microscopy. Buried single-crystal CoSi2 layers in the Si0.91Ge0.09 alloy containing ≈ 1 at% Ge were formed. The suicide formation causes an outdiffusion of Ge leading to an increase in the Ge concentration of the adjacent SiGe layers. In contrast, in the Si0.52Ge0.48 alloy no buried suicide layers could be produced.

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Palladium Nanowire Thin Films via Template Growth

MRS Proceedings ◽

10.1557/proc-775-p4.7 ◽

2003 ◽

Vol 775 ◽

Author(s):

Donghai Wang ◽

David T. Johnson ◽

Byron F. McCaughey ◽

J. Eric Hampsey ◽

Jibao He ◽

...

Keyword(s):

Thin Film ◽

Electron Microscopy ◽

Thin Films ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Conductive Substrate ◽

Palladium Nanowires ◽

Efficient Route ◽

Silica Thin Film

AbstractPalladium nanowires have been electrodeposited into mesoporous silica thin film templates. Palladium continually grows and fills silica mesopores starting from a bottom conductive substrate, providing a ready and efficient route to fabricate a macroscopic palladium nanowire thin films for potentially use in fuel cells, electrodes, sensors, and other applications. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate it is possible to create different nanowire morphology such as bundles and swirling mesostructure based on the template pore structure.

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Structural changes in titanium dioxide nanocrystals during plastic deformation

Journal of Applied Crystallography ◽

10.1107/s0021889805020418 ◽

2005 ◽

Vol 38 (5) ◽

pp. 749-756 ◽

Cited By ~ 5

Author(s):

Ulrich Gesenhues

Keyword(s):

Structural Changes ◽

Crystal Size ◽

Lower Layer ◽

High Energy ◽

Primary Crystal ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Hall Method ◽

Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

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Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽

10.3390/met11050800 ◽

2021 ◽

Vol 11 (5) ◽

pp. 800

Author(s):

Vladimír Girman ◽

Maksym Lisnichuk ◽

Daria Yudina ◽

Miloš Matvija ◽

Pavol Sovák ◽

...

Keyword(s):

Structural Changes ◽

Magnetic Measurements ◽

Structural Evolution ◽

High Energy ◽

Control Agent ◽

X Ray Diffraction ◽

Mechanically Alloyed ◽

X Ray ◽

Transmission Electron ◽

X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

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Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

Physical Chemistry Chemical Physics ◽

10.1039/c7cp03312e ◽

2017 ◽

Vol 19 (31) ◽

pp. 20867-20880 ◽

Cited By ~ 27

Author(s):

David C. Bock ◽

Christopher J. Pelliccione ◽

Wei Zhang ◽

Janis Timoshenko ◽

K. W. Knehr ◽

...

Keyword(s):

Electron Microscopy ◽

Structural Changes ◽

Ex Situ ◽

X Ray Diffraction ◽

X Ray ◽

Size Dependent ◽

Transmission Electron ◽

Dependent Behavior ◽

X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

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Limitations to the use of Sb as a Surfactant During SiGe MBE

MRS Proceedings ◽

10.1557/proc-533-289 ◽

1998 ◽

Vol 533 ◽

Author(s):

Glenn G. Jernigan ◽

Conrad L. Silvestre ◽

Mohammad Fatemi ◽

Mark E. Twigg ◽

Phillip E. Thompson

Keyword(s):

Electron Microscopy ◽

Thin Films ◽

Transmission Electron Microscopy ◽

Quantum Well ◽

Photoelectron Spectroscopy ◽

Surface Coverage ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Alloy Concentration

AbstractThe use of Sb as a surfactant in suppressing Ge segregation during SiGe alloy growth was investigated as a function of Sb surface coverage, Ge alloy concentration, and alloy thickness using xray photoelectron spectroscopy, x-ray diffraction, and transmission electron microscopy. Unlike previous studies where Sb was found to completely quench Ge segregation into a Si capping layer, we find that Sb can not completely prevent Ge segregation while Si and Ge are being co-deposited. This results in the production of a non-square quantum well with missing Ge at the beginning and extra Ge at the end of the alloy. We also found that Sb does not relieve strain in thin films but does result in compositional or strain variations within thick alloy layers.

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