Damage Accumulation in MgAl2O4 Crystals by Xe Ion Irradiations

1993 ◽  
Vol 316 ◽  
Author(s):  
N. Yu ◽  
M. Nastasi ◽  
M.G. Hollander ◽  
C.R. Evans ◽  
C.J. Maggiore ◽  
...  
Keyword(s):  
Temperature Effect ◽  
Damage Accumulation ◽  
Rutherford Backscattering Spectrometry ◽  
Surface Region ◽  
Irradiation Damage ◽  
Spinel Layer ◽  
Near Surface ◽  
Ion Channeling ◽  
Significant Temperature

ABSTRACTWe have studied the damage kinetics in single crystal MgAl2O4 (spinel) with (100) orientation under 370 keV Xe ion irradiations at temperatures of -100 and 400 C. In-situ Rutherford Backscattering Spectrometry (RBS) and ion channeling have been used to monitor the damage accumulation in spinel following sequential Xe ion irradiations. A significant temperature effect on the irradiation damage has been found. Channeling data show that at -100 C, the irradiated spinel layer reaches the same level as in a random spectrum at a dose of 8×1015 Xe/cm2 (20 DPA for peak damage), while at 400 C, the near surface region (50 nm) remains single-crystalline up to 2×1016 Xe/cm2.

Properties of Gallium Disorder and Gold Implants in GaN

2000 ◽  
Vol 647 ◽  
Author(s):  
W. Jiang ◽  
W.J. Weber ◽  
S. Thevuthasan ◽  
V. Shutthanandan
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
High Mobility ◽  
Surface Region ◽  
Intermediate Stage ◽  
Near Surface ◽  
Projected Range ◽  
Implantation Damage ◽  
The Mean ◽  
Fluence Range

AbstractEpitaxial single-crystal GaN films on sapphire were implanted 60° off the <0001> surface normal with 1 MeV Au2+ or 3 MeV Au3+ over a fluence range from 0.88 to 86.2 ions/nm2 at 180 and 300 K. The implantation damage was studied in-situ using 2 MeV He+ Rutherford backscattering spectrometry in channeling geometry (RBS/C). The disordering rate in the near- surface region is faster than at the damage peak. In all cases, results show an intermediate stage of Ga disorder saturation at the damage peak. During the thermal annealing at 870 K for 20 min, some Au implants in GaN diffuse into the amorphized surface region, while the remaining Au atoms distribute around the mean ion-projected-range. These results suggest a high mobility of both Ga defects and Au implants in GaN. Deeper damage implantation by 3 MeV Au3+ indicates that GaN cannot be completely amorphized up to the highest ion fluence (86.2 ions/nm2) applied at 300 K.

Nanoscale Mechanical Properties of In-Situ Tribofilms Generated from ZDDP and F-ZDDP with and without Antioxidants

2007 ◽  
Vol 7 (12) ◽  
pp. 4378-4390 ◽  
Author(s):  
Anuradha Somayaji ◽  
Ramoun Mourhatch ◽  
Pranesh B. Aswath
Keyword(s):  
Electron Microscopy ◽  
Wear Debris ◽  
Surface Region ◽  
Nucleation And Growth ◽  
Near Surface ◽  
Transmission Electron ◽  
Dialkyl Dithiophosphates ◽  
Wear Tests ◽  
Diphenyl Amine

Tribofilms with thickness ranging from 100–200 nm were developed in-situ during wear tests using a zinc dialkyl dithiophosphates (ZDDP) and fluorinated ZDDP (F-ZDDP). The influence of the antioxidant alkylated diphenyl amine on the formation and properties of these tribofilm is examined. Results indicate that the thickness of the tribofilms formed when F-ZDDP is used is always thicker than the tribofilm formed with ZDDP. In addition, in the presence of antioxidants the tribofilm thickness is increased. The hardness of these tribofilms in the absence of the antioxidants is significantly higher at the near surface region (0–30 nm) when compared to the films formed in the presence of antioxidant. Nanoscratch tests conducted to examine the abrasion resistance of the tribofilms also indicate that the tribofilms formed by F-ZDDP are more resistant to scratch compared to films formed by ZDDP. In the presence of antioxidant, tribofilms formed by F-ZDDP are significantly thicker while both films behave in a similar fashion in nanoscratch tests. Transmission electron microscopy of the wear debris formed during the tests were examined and results indicate the nucleation and growth of nanoparticles of Fe3O4 with an approximate size of 5–10 nm embedded within an otherwise amorphous tribofilm.

Heteroepitaxial Growth Of ZnO Films BY PLD

1997 ◽  
Vol 474 ◽  
Author(s):  
R. D. Vispute ◽  
V. Talyansky ◽  
Z. Trajanovic ◽  
S. Choopun ◽  
M. Downes ◽  
...  
Keyword(s):  
Oxygen Pressure ◽  
Surface Region ◽  
Optical Quality ◽  
Degree Of Crystallinity ◽  
Zno Films ◽  
Heteroepitaxial Growth ◽  
Near Surface ◽  
Ion Channeling ◽  
Deposition Parameters ◽  
High Degree

ABSTRACTHere we present our recent work on the fabrication of high crystalline and optical quality ZnO films on sapphire (001) by pulsed laser deposition. The influence of deposition parameters such as the substrate temperature, oxygen pressure, laser fluence, and pulse repetition rate on the crystalline quality of ZnO layers has been studied. The Ω-rocking curve FWHM of the (002) peak for the films grown at 750°, oxygen pressure 10−5 Torr was 0.17°. The XRD-Ф scans studies revealed that the films were epitaxial with a 30° rotation of the unit cell with respect to the sapphire to achieve a low energy configuration for epitaxial growth. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2–3% in the near surface region (-2000Å). The atomic force microscopy revealed smooth hexagonal faceting of the films. The optical absorption edge measured by UV-Visible spectroscopy was sharp at 383 nm. Excellent crystalline properties of these epi-ZnO/sapphire heterostractures are thus promising for III-V nitride heteroepitaxy.

In situ X-ray diffraction study of stacking fault formation in the near-surface region of transformation induced plasticity steels

2013 ◽  
Vol 530 ◽  
pp. 105-112 ◽  
Author(s):  
David Rafaja ◽  
Christina Krbetschek ◽  
Daria Borisova ◽  
Gerhard Schreiber ◽  
Volker Klemm
Keyword(s):  
Diffraction Study ◽  
Surface Region ◽  
Stacking Fault ◽  
X Ray Diffraction ◽  
Near Surface ◽  
Transformation Induced Plasticity ◽  
X Ray

scholarly journals In situ XRD measurements to explore phase formation in the near surface region

2019 ◽  
Vol 126 (20) ◽  
pp. 200901 ◽  
Author(s):  
Darina Manova ◽  
Stephan Mändl
Keyword(s):  
Phase Formation ◽  
Surface Region ◽  
Near Surface ◽  
In Situ Xrd

Damage Accumulation and Thermal Recovery in SrTiO3 Implanted with Au2+ Ions

1998 ◽  
Vol 540 ◽  
Author(s):  
S. Thevuthasan ◽  
W. Jiang ◽  
W.J. Weber ◽  
D.E. McCready
Keyword(s):  
Single Crystal ◽  
Damage Accumulation ◽  
Rutherford Backscattering Spectrometry ◽  
Recovery Process ◽  
Thermal Recovery ◽  
Broad Temperature Range ◽  
Maximum Temperature ◽  
Recovery Processes ◽  
Annealing Experiments

AbstractDamage accumulation and recovery process have been investigated in single crystal SrTiO3 irradiated with 1.0 MeV Au2+ using in-situ Rutherford Backscattering Spectrometry (RBS) in Channeling geometry. Samples were irradiated at a temperature of 200 K with ion fluences ranging from 5.0×1013 2.5×1014Au2+/cm2 (0.22 – 1.10 dpa at damage peak). Subsequent isochronal annealing experiments were performed to study damage recovery processes up to a maximum temperature of 870 K. At an ion fluence between 2.0–2.5×1014Au2+/cm2 (0.88 – 1.10 dpa), the implanted region, which is just below the surface, becomes amorphous. The recovery processes occur over a broad temperature range, and the damage created by low ion fluences, 5.0×1013 − 1.0×1014 Au2+/cm2, is almost completely recovered after annealing at 870 K.

In Situ Metal Matrix Composite Surfacing by Laser Surface Alloying

2011 ◽  
Vol 227 ◽  
pp. 84-91
Author(s):  
Jyotsna Dutta Majumdar
Keyword(s):  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Metal Matrix ◽  
Composite Layer ◽  
Metallic Matrix ◽  
Surface Region ◽  
Present Contribution ◽  
Near Surface ◽  
In Situ Reactions

Laser as a source of focused energy may be applied for the modification of microstructure and/or composition of the near surface region of a component. The technique may be applied for the development of a ceramic/intermetallics/interstitial compound dispersed metal matrix composite layer on the surface of metallic substrate by melting the substrate with a high power laser and simultaneous addition of alloy powders for the development of metal matrix composite layer by in-situ reactions. In the present contribution, development of metal-dispersed and intermetallic-dispersed matrix composite layer on the surface of metallic matrix has been discussed with a suitable example of its application.

Interfacial Strain Reliefs in Epitaxial YBa2Cu3O7–δ Thin Films Grown on SrTiO3 Buffered MGO Substrates

1997 ◽  
Vol 505 ◽  
Author(s):  
Xingtian Cui ◽  
Q. Y Chen ◽  
Yongxiang Guo ◽  
W. K. Chu
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Rutherford Backscattering Spectrometry ◽  
Epitaxial Thin Films ◽  
Cross Sectional ◽  
Ybco Films ◽  
Ion Channeling ◽  
Transmission Electron ◽  
Edge Dislocations

ABSTRACTHigh quality YBa2Cu3O7–δ, (YBCO) epitaxial thin films grown on MgO substrate with a strainrelieved SrTiO3 (STO) buffer layer have been investigated by Rutherford backscattering spectrometry (RBS), ion channeling and high resolution cross sectional transmission electron microscopy (XTEM). The in-situ growth of STO buffer layer along with the YBCO films was carried out by pulsed laser ablation. In this work, minimum yield of channeling measurements have shown that a very thin STO buffer layer is sufficient to grow highly crystalline YBCO thin films on MgO substrates. TEM studies showed that the STO layers were strain-relieved by an array of periodic edge dislocations. The YBCO films on STO buffer, as in those grown directly on an STO substrate, evolved from a strained layer to a largely dislocation free area.

Hgl−xCdxTe Near Surface Characterization using Computer Aided Rutherford Backscattering Spectrometry

1986 ◽  
Vol 90 ◽  
Author(s):  
T.-M. Kao ◽  
T. W. Sigmon
Keyword(s):  
Surface Characterization ◽  
Rutherford Backscattering Spectrometry ◽  
Grazing Angle ◽  
Surface Region ◽  
Rutherford Backscattering ◽  
Structural Defects ◽  
Near Surface ◽  
Lattice Disorder ◽  
Defect Densities ◽  
Distributed Dislocations

ABSTRACTIn this work, we report the use of Rutherford backscattering(RBS) measurements and computer simulations to provide accurate stoichiometry information and semi-quantitative defect densities for the near surface region of Hg1−xCdxTe (MCT). The accuracy of the Hg1−xCdx Te x-values determined by our method is found to be comparable to other commonly used methods, such as FTIR or the electron microprobe. The data obtained as structural defects from RBS channeling measurements are in basic agreement with other techniques, such as chemical etching. The sensitivity of the channeling measurement to uniformly distributed dislocations is found to be about 107−108 cm−2, however, for dislocations forming subgrains, the detectable level of dislocation comes to 105 – 106 cm−2. The depth profiles of lattice disorder resulting from ion implantation into MCT are also extracted from RBS channeling measurements using these simulation programs. These profiles are found to closely match the calculated profiles for the displaced atoms calculated using an implantation modeling program (TRIM). We also report on the use of channeling-in-grazing-angle-out technique for evaluating the stoichiometry of the first few monolayers of the MCT surface.

scholarly journals Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

2015 ◽  
Vol 9 (3) ◽  
pp. 971-988 ◽  
Author(s):  
M. Niwano ◽  
T. Aoki ◽  
S. Matoba ◽  
S. Yamaguchi ◽  
T. Tanikawa ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Near Surface ◽  
Snow Albedo ◽  
Physically Based ◽  
Significant Temperature ◽  
A Site ◽  
Temperature Surface

Abstract. The surface energy balance (SEB) from 30 June to 14 July 2012 at site SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic)-A, (78°03' N, 67°38' W; 1490 m a.s.l.) on the northwest Greenland Ice Sheet (GrIS) was investigated by using in situ atmospheric and snow measurements as well as numerical modeling with a one-dimensional multi-layered physical snowpack model called SMAP (Snow Metamorphism and Albedo Process). At SIGMA-A, remarkable near-surface snowmelt and continuous heavy rainfall (accumulated precipitation between 10 and 14 July was estimated to be 100 mm) were observed after 10 July 2012. Application of the SMAP model to the GrIS snowpack was evaluated based on the snow temperature profile, snow surface temperature, surface snow grain size, and shortwave albedo, all of which the model simulated reasonably well. Above all, the fact that the SMAP model successfully reproduced frequently observed rapid increases in snow albedo under cloudy conditions highlights the advantage of the physically based snow albedo model (PBSAM) incorporated in the SMAP model. Using such data and model, we estimated the SEB at SIGMA-A from 30 June to 14 July 2012. Radiation-related fluxes were obtained from in situ measurements, whereas other fluxes were calculated with the SMAP model. By examining the components of the SEB, we determined that low-level clouds accompanied by a significant temperature increase played an important role in the melt event observed at SIGMA-A. These conditions induced a remarkable surface heating via cloud radiative forcing in the polar region.

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