scholarly journals The Effect of Ion Irradiation on Inert Gas Bubble Mobility

1991 ◽  
Vol 235 ◽  
Author(s):  
Dale E. Alexander ◽  
R. C. Birtcher
Keyword(s):  
Electron Microscopy ◽  
Volume Diffusion ◽  
Ion Irradiation ◽  
Diffusion Mechanism ◽  
Inert Gas ◽  
Gas Bubble ◽  
Enhanced Diffusion ◽  
Transmission Electron ◽  
Radiation Enhanced Diffusion ◽  
Bubble Transport

ABSTRACTThe effect of Al ion irradiation on the mobility of Xe gas bubbles in Al thin films was investigated. Transmission electron microscopy was used to determine bubble diffusivities in films irradiated and/or annealed at 673K, 723K and 773K. Irradiation increased bubble diffusivity by a factor of 2–9 over that due to thermal annealing alone. The Arrehnius behavior and dose rate dependence of bubble diffusivity are consistent with a radiation enhanced diffusion phenomenon affecting a volume diffusion mechanism of bubble transport.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

Study of the Ion-Irradiation Behavior of Advanced SiC Fibers by Raman Spectroscopy and Transmission Electron Microscopy

2014 ◽  
Vol 98 (2) ◽  
pp. 675-682 ◽  
Author(s):  
Juan Huguet-Garcia ◽  
Aurélien Jankowiak ◽  
Sandrine Miro ◽  
Dominique Gosset ◽  
Yves Serruys ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Ion Irradiation ◽  
Sic Fibers ◽  
Transmission Electron ◽  
Irradiation Behavior

scholarly journals Carbon Nanofibers from Carbon Nanotubes by 1.2 keVAr+Sputtering at Room Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Shuang-Xi Xue ◽  
Qin-Tao Li ◽  
Xian-Rui Zhao ◽  
Qin-Yi Shi ◽  
Zhi-Gang Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Carbon Nanofibers ◽  
Carbon Nanoparticles ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Transmission Electron ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Carbon Nanowires

Multi-walled carbon nanotubes (MWCNTs) were irradiated by 1.2 keV Ar ion beams for 15–60 min at room temperature with current density of 60 µA/cm2. The morphology and microstructure are investigated by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that carbon nanofibers are achieved after 60 min ion irradiation and the formation of carbon nanofibers proceeds through four periods, carbon nanotubes—amorphous carbon nanowires—carbon nanoparticles along the tube axis—conical protrusions on the nanoparticles surface—carbon nanofibers from the conical protrusions.

scholarly journals The sintering kinetics of shellfish porcelain reinforced by sepiolite nanofibres

2018 ◽  
Vol 5 (10) ◽  
pp. 180483 ◽  
Author(s):  
Li Tian ◽  
Lijuan Wang ◽  
Kailei Wang ◽  
Yuedan Zhang ◽  
Jinsheng Liang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Diffusion Mechanism ◽  
Linear Shrinkage ◽  
Liquid Phase Sintering ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Fibre Pullout ◽  
Sintering Behaviour

The work investigated the effect of sepiolite nanofibres on mechanical properties and sintering behaviour of shellfish porcelain. Samples of shellfish porcelain reinforced by sepiolite nanofibres were fired in an electric furnace at 1150, 1200 and 1250°C for a period of 80, 100, 120 and 140 min. Sintered samples were characterized by flexural strength, fracture toughness, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results showed that 2 wt% sepiolite nanofibres could increase the flexural strength and fracture toughness of the porcelain bodies through the fibre pullout and the weak interface mechanisms. Sintering activation energies were determined according to the linear shrinkage results. It is found that the liquid-phase sintering mechanism of shellfish porcelain with sepiolite nanofibres is a diffusion mechanism. Porcelain without sepiolite is controlled by volume diffusion, and eventually, the grain boundary diffusion began to appear with the increase of sepiolite addition.

Characteristics of nanophase TiAl produced by inert gas condensation

1992 ◽  
Vol 7 (11) ◽  
pp. 2962-2970 ◽  
Author(s):  
H. Chang ◽  
C.J. Altstetter ◽  
R.S. Averback
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Large Fraction ◽  
Inert Gas ◽  
Full Density ◽  
Indentation Creep ◽  
Small Component ◽  
Grain Sizes ◽  
Transmission Electron ◽  
20 Nm

Nanophase TiAl, with grain sizes in the range of 10–20 nm, was synthesized by magnetron sputtering in an inert gas atmosphere and consolidated, in situ, under vacuum. The properties of the powders and sintered compacts were studied by transmission electron microscopy, scanning electron microscopy, calorimetry, Rutherford backscattering, and x-ray diffraction. Samples compacted at 1.0 GPa at room temperature had a large fraction of amorphous phase, while samples compacted at the same pressure and 250 °C were predominantly the equilibrium γ phase. An enthalpy change of 22 kJ/g-atom was measured during a DSC scan over the temperature range 125–450 °C, which is approximately the range over which crystallization occurs. Nearly full density could be achieved by sintering at 450 °C without significant, concomitant grain growth. The Vickers microhardness of these samples at room temperature and at −30 °C revealed an inverse Hall–Petch relationship at small grain sizes, 10–30 nm, and the usual Hall–Petch behavior at larger grain sizes. A small component of indentation creep was also observed. The maximum hardness is 4 times larger than that of a cast TiAl specimen of the same composition. The Vickers hardness was also observed to decrease rapidly with temperature above 200 °C.

scholarly journals Secondary magnetite in ancient zircon precludes analysis of a Hadean geodynamo

2018 ◽  
Vol 116 (2) ◽  
pp. 407-412 ◽  
Author(s):  
Fengzai Tang ◽  
Richard J. M. Taylor ◽  
Josh F. Einsle ◽  
Cauê S. Borlina ◽  
Roger R. Fu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Remanent Magnetization ◽  
Diffusion Mechanism ◽  
Aqueous Fluid ◽  
Pipe Diffusion ◽  
Transmission Electron ◽  
Igneous Zircon ◽  
Jack Hills ◽  
Magnetic Inclusions

Zircon crystals from the Jack Hills, Western Australia, are one of the few surviving mineralogical records of Earth’s first 500 million years and have been proposed to contain a paleomagnetic record of the Hadean geodynamo. A prerequisite for the preservation of Hadean magnetization is the presence of primary magnetic inclusions within pristine igneous zircon. To date no images of the magnetic recorders within ancient zircon have been presented. Here we use high-resolution transmission electron microscopy to demonstrate that all observed inclusions are secondary features formed via two distinct mechanisms. Magnetite is produced via a pipe-diffusion mechanism whereby iron diffuses into radiation-damaged zircon along the cores of dislocations and is precipitated inside nanopores and also during low-temperature recrystallization of radiation-damaged zircon in the presence of an aqueous fluid. Although these magnetites can be recognized as secondary using transmission electron microscopy, they otherwise occur in regions that are indistinguishable from pristine igneous zircon and carry remanent magnetization that postdates the crystallization age by at least several hundred million years. Without microscopic evidence ruling out secondary magnetite, the paleomagnetic case for a Hadean–Eoarchean geodynamo cannot yet been made.

scholarly journals Examining Atomistic Defect-Boundary Interactions Induced by Ion Irradiation using Aberration Corrected Transmission Electron Microscopy

2013 ◽  
Vol 19 (S2) ◽  
pp. 1982-1983
Author(s):  
J.A. Aguiar ◽  
M. Chi ◽  
P. Kotula ◽  
Z. Bi ◽  
O. Anderoglu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
Transmission Electron ◽  
Aberration Corrected ◽  
Defect Boundary

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

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