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

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.

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

IS Selective CVD an Improvement for the Titanium Silicide Process in Sub-Quarter Micron Technology? A Phase Formation Study Using X-ray Diffraction

1998 ◽  
Vol 514 ◽  
Author(s):  
Ronnen Roy ◽  
Cryil Cabral ◽  
Christian Lavoie ◽  
Jean Jordan-Sweet ◽  
R. Viswanathan ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Formation ◽  
Chemical Vapor ◽  
Titanium Silicide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silicon Chips ◽  
In Situ Xrd ◽  
Silicon Structures

ABSTRACTThe C54 phase formation process of titanium silicide was studied after selective chemical vapor despostion (CVD) onto very small silicon structures, to ascertain the efficacy of CVD to form low resistance contacts in sub-quarter micron technology. Because the selective CVD process forms silicide on any exposed silicon in a CMOS device, the process was studied on both polysilicon and Si (100) chips. The structures consisted of arrays of about 106 identical lines, 0.1 2.0 μm in width, depending on the chip. The CVD process employed TiCl4 and SiH4 for the most part as process gases and the depostion temperature ranged from 730–825°C. X-ray diffraction (XRD) was used to document the amount of C54 phase present after deposition. In some cases samples were annealed after deposition and the phase transformation behavior studied by in-situ XRD. The latter technique employed a synchrotron radiation source providng for rapid XRD spectra collection, so that the C49-C54 phase transformation could be examined with great precision in real time during rapid thermal annealing. The results of CVD depositions were compared to titanium silicide formed by sputter deposition of Ti on identical silicon chips, followed by a typical salicide protocol. Although the phase formation is affected by both film thickness and substrate temperature during CVD, the general result is that the C54 formation is more facile using the CVD process, especially for the smallest line dimensions. The findings are discussed with respect to nucleation processes occurring during growth and post-deposition thermal processing.

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.

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.

In Situ Tem Studies of The Growth of Strained Si1-xGex By Solid Phase Epitaxy

1990 ◽  
Vol 202 ◽  
Author(s):  
D. C. Paine ◽  
D. J. Howard ◽  
N. D. Evans ◽  
D. W. Greve ◽  
M. Racanelli ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Surface Region ◽  
In Situ Tem ◽  
Solid Phase Epitaxy ◽  
Near Surface ◽  
Strained Layer ◽  
Epitaxial Regrowth

ABSTRACTIn this paper we report on the epitaxial growth of strained thin film Si1-xGex on Si by solid phase epitaxy. For these solid phase epitaxy experiments, a 180-nm-thick strained-layer of Si1-xGex with xGe=11.6 at. % was epitaxially grown on <001> Si using chemical vapor deposition. The near surface region of the substrate, including the entire Si1-xGex film, was then amorphized to a depth of 380 nm using a two step process of 100 keV, followed by 200 keV, 29Si ion implantation. The epitaxial regrowth of the alloy was studied with in situ TEM heating techniques which enabled an evaluation of the activation energy for strained solid phase epitaxial regrowth. We report that the activation energy for Si1-xGex (x=l 1.6 at. %) strained-layer regrowth is 3.2 eV while that for unstrained regrowth of pure Si is 2.68 eV and that regrowth in the alloy is slower than in pure Si over the temperature range 490 to 600°C.

GaAs(100) Surface Modifications at Elevated Temperatures, Studied By In-Situ Spectroscopic Ellipsometry

1990 ◽  
Vol 202 ◽  
Author(s):  
Huade Yao ◽  
Paul G Snyder ◽  
John A Woollam
Keyword(s):  
Spectroscopic Ellipsometry ◽  
Room Temperature ◽  
Molecular Beam ◽  
Elevated Temperatures ◽  
Surface Region ◽  
Gaas Surface ◽  
Near Surface ◽  
Before And After ◽  
Surface Changes

ABSTRACTSpectroscopic ellipsometric (SE) measurements of GaAs (100) were carried out in an ultrahigh vacuum (UHV) chamber, without arsenic overpressure, at temperatures ranging from room temperature (RT) to ∼610°C. Surface changes induced at elevated temperatures were monitored by in-situ spectroscopic ellipsometry. The SE data clearly displayed in real time the process of desorption of the GaAs-surface-oxide overlayer at ∼580°C. In addition, changes in the near-surface region were observed before and after the oxide desorption. The near-subsurface region (top 50–100 Å) became less optically dense after being heated to 540°C or higher. For comparison, a pre-arsenic-capped molecular-beam-epitaxy (MBE)-grown GaAs surface was also studied. After the arsenic cap was evaporated off at ∼350°C, this surface remained smooth and clean as it was heated to higher temperatures.

scholarly journals Energetic Cost for Being “Redox-Site-Rich” in Pseudocapacitive Energy Storage with Nickel – Aluminum Layered Double Hydroxide Materials

2020 ◽  
Author(s):  
Xianghui Zhang ◽  
Cody B. Cockreham ◽  
Esra Yilmaz ◽  
Gengnan Li ◽  
Nan Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Specific Capacity ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Energetic Cost ◽  
Near Surface ◽  
In Situ Xrd ◽  
Redox Sites ◽  
Double Hydroxides

<div> <div> <div> <p>Defining the energetic landscape of pseudocapacitive materials such as transition metal layered double hydroxides (LDHs) upon redox site enrichment is essential to harness their power for effective energy storage. Here, coupling acid solution calorimetry, in situ XRD, and in situ DRIFTS, we demonstrate that as the Ni/Al ratio increases, both as-made (hydrated) and dehydrated NiAl-LDH samples are less stable evidenced by their enthalpies of formation. Moreover, the higher specific capacity at intermediate Ni/Al ratio of 3 is enabled by effective water – LDH interactions, which energetically stabilizes the excessive near-surface Ni redox sites, solvates intercalated carbonate ions, and fills the expanded vdW gap, paying for the “energetic cost” of being “redox site rich”. Thus, from a thermodynamic perspective, engineering molecule/solids – LDH interactions on the nanoscale with confined guest species other than water, which energetically impose stronger stabilization, may help us to achieve their specific capacitance potential. </p> </div> </div> </div>

scholarly journals Energetic Cost for Being “Redox-Site-Rich” in Pseudocapacitive Energy Storage with Nickel – Aluminum Layered Double Hydroxide Materials

2020 ◽  
Author(s):  
Xianghui Zhang ◽  
Cody B. Cockreham ◽  
Esra Yilmaz ◽  
Gengnan Li ◽  
Nan Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Specific Capacity ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Energetic Cost ◽  
Near Surface ◽  
In Situ Xrd ◽  
Redox Sites ◽  
Double Hydroxides

<div> <div> <div> <p>Defining the energetic landscape of pseudocapacitive materials such as transition metal layered double hydroxides (LDHs) upon redox site enrichment is essential to harness their power for effective energy storage. Here, coupling acid solution calorimetry, in situ XRD, and in situ DRIFTS, we demonstrate that as the Ni/Al ratio increases, both as-made (hydrated) and dehydrated NiAl-LDH samples are less stable evidenced by their enthalpies of formation. Moreover, the higher specific capacity at intermediate Ni/Al ratio of 3 is enabled by effective water – LDH interactions, which energetically stabilizes the excessive near-surface Ni redox sites, solvates intercalated carbonate ions, and fills the expanded vdW gap, paying for the “energetic cost” of being “redox site rich”. Thus, from a thermodynamic perspective, engineering molecule/solids – LDH interactions on the nanoscale with confined guest species other than water, which energetically impose stronger stabilization, may help us to achieve their specific capacitance potential. </p> </div> </div> </div>

Cathodoluminescence Deep Level Spectroscopy of Etched and In-Situ Annealed 6H-SiC

1998 ◽  
Vol 512 ◽  
Author(s):  
A. P. Young ◽  
K. Aptowitz ◽  
L. J. Brillson
Keyword(s):  
Electron Beam ◽  
Deep Level ◽  
Surface Region ◽  
Energy Electron ◽  
Temperature Dependent ◽  
Near Surface ◽  
Electron Beam Excitation ◽  
Beam Excitation ◽  
Variable Energy

ABSTRACTThrough variable-energy electron beam excitation (0.5 keV-2.0 keV), we observe depth dependent differences in the cathodoluminescence spectra of 6H-SiC (0001) Si-terminated surfaces. The etched SiC exhibits three deep level defects in the near-surface region, including a defect peak observed at 0.92 eV, known to be associated with vanadium. In-situ annealing produces a dramatic relative decrease in the luminescence from vanadium impurities near the surface after annealing to 500 °C, and then the subsequent re-emergence of vanadium in the nearsurface regime after annealing to 810 °C. This temperature-dependent redistribution suggests either diffusion or segregation of vanadium from the bulk up toward the near-surface region.

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