Effect of immersion in water partially alkali-activated materials obtained of tungsten mine waste mud
Silva I., Castro-Gomes J. & Albuquerque A.
Construction and Building Materials, V. 35, 117-124.
Alkali-activated binders can be obtained using several sources of alumino-silicate materials, from calcinated
clays, like kaolin, to industrial by-products, such as fly ash and, more recently, to calcinated waste mud from mining activities. The technology to obtain alkali-activated binders, also designated as geopolymers, is gaining increasing interest, since, in some cases, the properties of geopolymeric materials
are superior to other existing cementitious systems. The research presented in this paper intends to deepen
the knowledge regarding the properties of geopolymeric materials obtained using tungsten mining waste mud, particularly to study its behaviour after being immersed in water. However, in the current work, focus is given to follow compressive strength results in partially alkali-activated samples immersed in water, during different curing periods of time. Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy analysis (FTIR) were also utilised to investigate changes in the microstructure at different conditions of water immersion. A significant decrease in compressive strength occurring after 24 h of immersion in water was found out, of specific partially alkali-activated materials, despite of its initial high compressive strength after 35 days curing, at different temperatures.
Combined in situ electrochemical impedance spectroscopy UV/Vis and AFM studies of Ag nanoparticle stability in perfluorinated films
K. Yliniemi, a, b, B. Özkaya, b, N. Alissawi, c, V. Zaporojtchenko, c, T. Strunskus, c, B.P. Wilson, a,b,1, F. Faupel, c, G. Grundmeier, b
a Aalto University, Department of Chemistry, P.O. Box 16100, 00076 AALTO Espoo, Finland
b University of Paderborn, Institute for Polymer Materials and Processes, Faculty of Natural Science, Warburger Str. 100, 33098 Paderborn, Germany
c Institute for Materials Science, Multicomponent Materials, Faculty of Engineering, Christian-Albrechts University at Kiel, Kaiserstr. 2, 24143 Kiel, Germany
1 ASTUTE, College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP, UK.
Materials Chemistry and Physics Volume 134, Issue 1, 15 May 2012, Pages 302–308
In situ electrochemical UV/Vis spectroscopic analysis in combination with AFM measurements were performed to study the... more In situ electrochemical UV/Vis spectroscopic analysis in combination with AFM measurements were performed to study the reactivity of Ag nanoparticles sandwiched in between two polytetrafluorethylene (PTFE) films. The electrolyte uptake in the film was correlated with the onset of the changes in the surface plasmon resonance by measuring the film capacitance and the surface plasmon resonance peak simultaneously as a function of the exposure time. AFM studies indicate that both particle ripening and Ag dissolution take place and the dissolution kinetics was shown to decrease with increasing covering film thickness.
Synthesis and Characterization of Bi2O3–doped with Lanthanum by Electrospinning Method
International Journal of Material Science and Electronics Research, Vol. 1, No. 2, July-Dec. 2010, pp. 81-85
Ş. Durmuşoğlu, S. Keskin, ibrahim Uslu, A. Aytimur, A. Akdemir
Electrospinning process was utilized to fabricate lanthanum doped bismuth ultrafine nanofibers. PVA was used as... more Electrospinning process was utilized to fabricate lanthanum doped bismuth ultrafine nanofibers. PVA was used as precursor polymer solution with bismuth acetate/lanthanum acetate, followed by calcination at 800oC. The produced nanofibers and calcined crystal structures were characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results indicated that samples after calcination should be sintered more than one to obtain pure crystalline phase.
Boron Carbide Deposition on Urania and Urania-Gadolinia Fuels
Nuclear Technology volume 135 issue 3 2001
H. Dışbudak, ibrahim uslu, A.Y. Bilgesu, G. Gündüz
Pure uranium dioxide and uranium dioxide-gadolinium oxide (5 and 10%) fuels used in this study were prepared by the... more Pure uranium dioxide and uranium dioxide-gadolinium oxide (5 and 10%) fuels used in this study were prepared by the solution-gelation (sol-gel) technique. The fuels were then coated with boron carbide by chemical vapor deposition. Boron carbide was produced from the reaction of carbon tetrachloride and boron trichloride with excess hydrogen, in a tube furnace at 1000, 1100, and 1175 deg. C. The Fourier transform infrared data of boron carbide deposited on a silica glass were in agreement with the ones in the literature. The experiments showed that the composition of the coating changed with deposition temperature. There was boron-rich coating at low-temperature deposition, and carbon-rich coating at high-temperature deposition. The morphology and the thickness of the coating have been investigated by using scanning electron microscopy and X-ray diffraction spectroscopy.
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Seen by:Powder characteristics and microstructure of uranium dioxide and uranium dioxide-gadolinium oxide fuel
Journal of Nuclear Materials
Volume 231, Issues 1-2, July 1996, Pages 113-120
G. Gündüz, ibrahim Uslu
Three different fuels UO2-only, UO2-Gd2O3(5%), and UO2-Gd2O3(10%) were produced by sol-gel technique. Their powder... more Three different fuels UO2-only, UO2-Gd2O3(5%), and UO2-Gd2O3(10%) were produced by sol-gel technique. Their powder characteristics such as flowability, BET surface area, average pore diameter, and cumulative pore volume were determined. The pore size distributions of powders, green pellets, and sintered fuels were determined by using a mercury porosimeter. The theoretical densities of sintered fuels were found to be 98.01, 95.3, and 95.9%, respectively. Their ruggedness fractal dimensions were 1.111, 1.044, and 1.042, while the fractal dimensions associated with the size distribution of grains were 1.44, 1.58, and 1.60, respectively.
Boron-nitride coated nuclear fuels
Nuclear technology
1996, vol. 116, no1, pp. 78-90
G. Gündüz, ibrahim Uslu, H.H. Durmazuçar
Pure urania- and urania-gadolinia-containing fuel pellets were coated with boron nitride (BN) to improve the physical... more Pure urania- and urania-gadolinia-containing fuel pellets were coated with boron nitride (BN) to improve the physical and neutronic properties of the fuel. The BN coating seems to have a technological advantage over zirconium-diboride coating. The BN is chemically inert, corrosion resistant, withstands rapid temperature changes, and has a high thermal conductivity. Since gadolinia fuel has low thermal conductivity, the gadolinia content can be lowered in the fuel by coating it with BN. In fact, the existence of two burnable absorbers in a fuel introduces desired nuclear properties since gadolinia is a fast-burning and boron a slow-burning element. The BN was deposited on fuel from two different sources, (a) from the reaction of boron trichloride (BCl3) and ammonia (NH3) at 875 K and (b) from the decomposition of trimethylamine borate complex at 1200 K. The infrared and X-ray diffraction (XRD) spectra of BN from both precursors agreed with the available data in the literature. However BN powder from borane complex had a shifted XRD peak due to the presence of carbonaceous material in the structure. The BN powder-coated fuels were heated to 1400, 1525, and 1600K to sinter the BN. The examination under scanning electron microscope showed that grainy, rodshaped and layered BN coatings were achieved. Rodshaped structures were usually seen on gadolinia fuels. The increased thickness of coating favors the formation of a glassy looking layer. The BN from a borane complex seems to form a layered structure more easily than the BN from BCl3. The BN coated the surface of the fuels, and it did not penetrate into the fuels.
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Seen by:FABRICATION AND CHARACTERIZATION OF BORON DOPED ZIRCONIUM OXIDE NANOFIBERS
BALKAN PHYSICS LETTERS
BPL, 19, 191026, pp. 232 – 239, (2011)
23 February 2011
ibrahim Uslu, M.K. Öztürk, T. Tunc, T.C. Karabulut, S. Keskin
Recently, considerable attention has been focused on zirconium oxide (ZrO2) which exhibits many desirable structural... more Recently, considerable attention has been focused on zirconium oxide (ZrO2) which exhibits many desirable structural and electronic properties and has been used in many applications. For example it is a very attractive and promising material for low-voltage and short-wavelength electro-optical devices such as light emitting diodes and laser diodes; it also has other applications such as gas sensors and varistors [1-4]. This study is related to the preparation of boron doped ZrO2 material. The first step was the preparation of composite by mixing zirconium acetate with polyvinyl alcohol (PVA) at a suitable temperature [5]. The resulting composite polymer was doped with boron using boric acid as boron source and then electrospun giving nano fibers. Finally, the resulting nano fibers were subjected to a thermal treatment at 250 oC, 500 oC, 800 oC to elucidate their morphological properties. The conductivity of the nano fibers obtained was measured with four probe technique and the boron supported polymer was observed to have a higher conductivity. The Differential Scanning Calorimetry (DSC) results indicate that the glass transition (Tg) and melting temperatures (Tm) showed great change with the addition of boron and boron doped fibers were observed to degrade at higher temperatures. The SEM appearance of the fibers showed that the addition of boron resulted in the formation of cross linked bright surfaced fibers.
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Seen by:Preparation and Characterization of Neodymia Doped PVA/Zr-Ce Oxide Nanocrystalline Composites via Electrospinning Technique
Materials and Manufacturing Processes
Volume 26, Issue 11, 2011
10.1080/10426914.2011.551954S.
S. Keskin, ibrahim Uslu, T.Tunç, M.Öztürk, A. Aytimur
In this study, neodymia doped poly(vinyl) alcohol/zirconium–cerium acetate (PVA/Zr-Ce) nanofibers were prepared using... more In this study, neodymia doped poly(vinyl) alcohol/zirconium–cerium acetate (PVA/Zr-Ce) nanofibers were prepared using the electrospinning technique, and then calcined at 800°C for 2 hours. For this purpose, PVA/Zr-Ce polymer solutions doped with different concentrations of neodymia were prepared using electrospinning technique, and then calcined and sintered at 800°C for 2 hours. The effect of neodymia doping was investigated in terms of solution properties, morphological changes and thermal characteristics. The fibers were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The measurements showed that the conductivity, pH, viscosity, and surface tension of the hybrid polymer solutions have decreased with increasing Nd acetate content. The FT-IR spectra of the fibers were in good accordance with the literature. The average crystal size values for calcined and sintered samples which were obtained from precursor solutions were calculated. XRD analysis showed that the crystallite size was decreased with increasing Nd content. This result is verified by the calculation of the total areas of the peaks appeared in the XRD spectra. The very sharp and high intense peaks found in the diffraction patterns revealed the crystalline nature of the product. Moreover, the SEM micrograph of the fibers showed that the average fiber diameters decreased with increasing Nd content.
Fabrication and characterization of boron doped BaZrO3 nanofibers via an electrospinning technique
Journal of Ceramic Processing Research. Vol. 12, No. 5, pp. 549~554 (2011)
T. Tunc, ibrahim Uslu, S. Keskin
In this study, boron doped and undoped poly(vinyl) alcohol/zirconium-barium acetate (PVA/Zr-Ba) nanofibers were... more
In this study, boron doped and undoped poly(vinyl) alcohol/zirconium-barium acetate (PVA/Zr-Ba) nanofibers were prepared using an electrospinning technique then calcinated at three different temperatures; 250 oC, 500 oC, 800 oC for 2 h. The
originality of this study is the addition of boron to metal acetates. The fibers were characterized by FT-IR, DSC, XRD and SEM. The addition of boron did not only increase the thermal stability of the fibers, but also increased their diameters, which gave stronger fibers. The FT-IR spectra of the fibers were in good accordance with literature data. The DSC results indicate that the glass transition (Tg) and melting temperatures (Tm) showed a change with the addition of boron. Also, boron doped fibers were observed to degrade at higher temperatures. XRD analyses showed that after further heat treatment at 800 oC, zirconia exists in two phases of tetragonal and monoclinic modifications. The systematic evolution of morphological features in the spun and the processed fibers were studied by scanning electron microscopy. The SEM appearance of the fibers showed
that the addition of boron resulted in the formation of cross linked bright surfaced fibers.
Preparation of Gadolina Stabilized Bismuth Oxide Doped with Boron via Electrospinning Technique
JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS
J Inorg Organomet Polym (2012) 22:105–111
Tuncay Tunc¸ ibrahim Uslu, Senol Durmusoğlu, Selda Keskin, Arda Aytimur, Ahmet Akdemir
In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) nanofibers were... more
In this study, boron doped and undoped poly (vinyl) alcohol/bismuth–gadolina acetate (PVA/Bi–Gd) nanofibers were prepared using electrospinning technique then calcinated at 800 °C for 2 h.
The originality of this study is the addition of boron to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and thermal characteristics.
The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3–La2O3 nanocrystalline powder ceramic structures sintered at 800 °C have surface areas of 59.72 and 39.80 m2/g, respectively.
Production and characterization of poly(vinyl alcohol)/poly(vinylpyrrolidone) iodine/poly(ethylene glycol) electrospun fibers with (hydroxypropyl)methyl cellulose and aloe vera as promising material for wound dressing
Journal of Applied Polymer Science
Volume 124, Issue:4 pp: 3520-3524, 2012
DOI: 10.1002/app.35525
ibrahim Uslu, A. Aytimur
Biocompatible poly(vinyl alcohol)/poly (vinylpyrrolidone) iodine/poly(ethylene glycol) fibers containing... more Biocompatible poly(vinyl alcohol)/poly (vinylpyrrolidone) iodine/poly(ethylene glycol) fibers containing (hydroxypropyl)methyl cellulose (HPMC) and aloe vera were successfully prepared by electrospinning their aqueous solution. Aloe vera which is known to be effective in the treatment of various wounds was added to the polymer solution. HPMC was added to the system as the water retention agent. The hybrid fiber mats were subjected to detailed analysis using a differential scanning calorimeter, a scanning electron microscope (SEM), and a Fourier transform infrared spectrometer. Images obtained from the SEM showed that the polymer fibers were linear, homogenous, and contained no beading. The fiber diameters ranged between 100 and 900 nm. It was seen that the electrospun mats obtained could potentially be used as a material for dressing wounds. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
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Ceramics International
Available online 20 January 2012
A. Aytimur, I. Uslu, S. Koçyiğit, F. Özcan
In this study, magnesia stabilized zirconia based nanocrystalline ceramics were produced through a polymer precursor... more In this study, magnesia stabilized zirconia based nanocrystalline ceramics were produced through a polymer precursor route using gadolinium and boron. The powders were characterized during the various steps by structural and morphological techniques (FT-IR, XRD, and SEM). XRD results proved that a tetragonal phase is predominant for all samples with varying magnesium contents and no monoclinic zirconia solid solution appears. The crystallite sizes of the samples were calculated using Scherrer equation. The smallest crystallite size was obtained for the sample containing Zr/Mg/Ce/Gd/B ratio of 82/0/10/8/0. The lattice parameters were calculated for cubic, tetragonal, hexagonal, and orthorhombic structures. SEM results show all the samples have spherical grains. The average grain diameters were calculated for all the samples. The smallest average grain diameter was obtained for the sample containing Zr/Mg/Ce/Gd/B ratio of 82/0/10/8/0.
Damage assessment and retrofit study for the Luxor Memnon Colossi
Casciati S. and Osman A. M. (2005). “Damage assessment and retrofit study for the Luxor Memnon Colossi”. Structural Control & Health Monitoring, 12(2), 139-156. ISSN: 1545-2255.
DATE AND PLACE OF PUBBLICATION: April-June 2005; John Wiley & Sons, Ltd., Chichester PO19 8SQ, W Sussex, England.
ABSTRACT. The structural behaviour of large, monolithic, ancient monuments consisting of heavy stone blocks connected... more
ABSTRACT. The structural behaviour of large, monolithic, ancient monuments consisting of heavy stone blocks connected one to the other by the gravity load alone, without the use of mortar, is investigated. The Memnon Colossi, which were built fourteen centuries before Christ at Luxor in Egypt, are the case study for this construction technique. This paper summarizes the results of studies carried out on this structure within the CHIME (Conservation of Historical Monuments in the Mediterranean Area) project, funded by the European Commission.
The modal frequencies of the two statues were identified experimentally from ambient vibration measurements. Analytical models using the finite element method were also elaborated to compare the numerical results with the experimental ones, and to perform dynamic analyses. The results indicated that the distributed cracks characterizing the current state of the structure, play a significant role in the static and dynamic response of the monument. In view of the monuments’ rehabilitation, an innovative technology, based on fastening the cracked blocks by pre-tensioned wires of shape memory alloy, is proposed and numerically simulated.
KEY WORDS: monument; modal identification; damage assessment; retrofit; shape memory alloy
Epitaxy and chemical reactions during thin-film formation from low-energy ions: new kinetic pathways, new phases, and new properties
Nicole Herbots, O.C. Hellman
ARIZONA STATE UNIVERSITY, Departmentof PhysicsandAstronomy, Tempe AZ 85287
0. Vancauwenberghe* MASSACHUSETTS INSTITUTE OFTECHNOLOGY, DepartmentofMaterialsScience & Engineering,Cambridge, MA 02139
Ref: Mat. Res. Soc. Symp. Proc. Vol. 235. pp. 749-762 (1992)
ABSTRACT
Three important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of... more
ABSTRACT
Three important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of material into a substrate, the enhancement of atomic mobility in the subsurface, and the modification of growth kinetics it creates. All lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. The fundamental understanding and new applications of low temperature kinetics induced by low energy ions in thin film growth and surface processing of semiconductors are reviewed. It is shown that the mechanism of IBD growth can be understood and computed quantitatively using a simple model including ion induced defect generation and sputtering, elastic recombination, thermal diffusion, chemical reactivity, and desorption. The energy, temperature and dose dependence of growth rate, epitaxy, and chemical reaction during IBD is found to be controlled by the net recombination rate of interstitials at the surface in the case of epitaxy and unreacted films, and by the balance between ion beam decomposition and phase formation induced by ion beam generated defects in the case of compound thin films. Recent systematic experiments on the formation of oxides and nitrides on Si, Ge/Si(100), heteroepitaxial SixGe1−x/Si(100) and GaAs(lOO) illustrate applications of this mechanism using IBD in the form of Ion Beam Nitridation (IBN), Ion Beam Oxidation (IBO) and Combined Ion and Molecular beam Deposition (CIMD). It is shown that these techniques enable (1) the formation of conventional phases in conditions never used before, (2) the control and creation of properties via new degrees of freedom such as ion energy and lowered substrate temperatures, and (3) the formation of new metastable heterostructures that cannot be grown by pure thermal means.
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Seen by: and 6 moreRandom imperfection fields to model the size effect in laboratory wood specimens
Casciati S. and Domaneschi M. (2007). “Random imperfection fields to model the size effect in laboratory wood specimens”. Structural Safety, 29(4), 308-321. ISSN: 0167-4730.
DATA E LUOGO DI PUBBLICAZIONE: October 2007; Elsevier Science Bv, 1000 AE Amsterdam, Netherlands.
ABSTRACT. The composite nature of a wood continuum prevents one from extrapolating the results of laboratory tests on... more
ABSTRACT. The composite nature of a wood continuum prevents one from extrapolating the results of laboratory tests on standard wood specimens to structural elements of significant size. Therefore, these elements are usually tested under standardized loading conditions in order to detect a sort of average material behaviour.
In this paper, the initial step consists, instead, of testing the material specimens. The extension of the results to structural elements is then pursued by introducing a random field, or, in a discretized model, a random array of imperfections.
The calibration of the suitable spatial distribution of the imperfections is then investigated by a mixed experimental–numerical approach, for a reference beam. The analyses on the relative finite elements model are iterated to match the response of the full scale laboratory tests.
KEYWORDS: Biaxial tests; Finite element model; Imperfections; Laboratory tests; Random field; Wood specimens
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Seen by:Structural components in shape memory alloy for localized energy dissipation
Casciati S. and Faravelli L. (2008). “Structural components in shape memory alloy for localized energy dissipation”. Computers & Structures, 86(3-5), 330-339. ISSN: 0045-7949.
DATE AND PLACE OF PUBBLICATION: February 2008; Pergamon–Elsevier Science Ltd, Kidlington, Oxford OX5 1GB, Oxon, England.
ABSTRACT: Cu-based shape memory alloys (SMA) offer their feature of superelastic hysteresis at sustainable costs, and... more
ABSTRACT: Cu-based shape memory alloys (SMA) offer their feature of superelastic hysteresis at sustainable costs, and for a window of temperatures applicable to most of civil engineering applications. Structural components can easily be obtained in the form of wires or plates. Their insertion in standard structures produces devices for local energy dissipation under dynamic loading. Several solutions are experimentally investigated throughout the paper.
KEYWORDS: Dissipative devices; Hysteresis; Shaking table test; Shape memory alloys; Superelasticity; Training
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Seen by: and 8 moreExperimental and numerical studies toward the implementation of shape memory alloy ties in masonry structures
Casciati S. and Hamdaoui K. (2008). “Experimental and numerical studies toward the implementation of shape memory alloy ties in masonry structures”. Smart Structures and Systems, 4(2), 153-169. ISSN: 1738-1584.
DATA E LUOGO DI PUBBLICAZIONE: March 2008; Techno-Press, Daejeon 305-600, South Korea.
ABSTRACT: The use of pre-tensioned shape memory alloy (SMA) wires to retrofit historic masonry structures is... more
ABSTRACT: The use of pre-tensioned shape memory alloy (SMA) wires to retrofit historic masonry structures is investigated. A small wall, serving as a prototype masonry specimen, is constructed to undergo a series of shaking table tests. It is first studied in its original state, and its dynamic characteristics (in terms of modal frequencies) are extracted from the recorded signals. The results are then compared with those obtained when an increasing number of couples of pre-stressed SMA wires are introduced in the specimen to link the bricks together. A threedimensional finite element model of the specimen is developed and calibrated according to the modal parameters identified from each experimental test (with and without SMA wires). The calibration process is conducted by enhancing the masonry mechanical behaviour. The results and the effectiveness of the approach are presented.
KEYWORDS: masonry; numerical modelling; shaking table tests; shape memory alloys; system identification.
Ion beam oxidation of GaAs: The role of ion energy
O. Vancauwenberghe, N. Herbots. H. Manoharan,a) and M. Ahrens
Massachusetts Institute of Technology, Cambridge,
Maassachusetts 02139
J. Vac. Sci. Technot A 9 (3), May/Jun 1991, pp. 1035-1039
In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam... more
In this work, room temperature oxidation of GaAs was investigated using ion beam oxidation (mO). In lBO, an ion beam is used to introduce oxygen athermally into the substrate, in this case GaAs. GaAs bonds are broken upon collision with the ions, making gallium and arsenic atoms readily available to react with the oxygen species. Ion beam oxidation of GaAs at room temperature was studied as a function ofoxygen ion energy between 500 and is keY. The ion beam oxidized GaAs was characterized in situ by Auger electron spectroscopy (AES) and ex situ with x-ray photoelectron spectroscopy (XPS) for accurate determination of the film chemical composition. Below 1 keY, a thin oxide film is formed: it is composed of Ga20 3 and AS20 3 with almost no metallic arsenic, and presents insulating properties.
As the ion energy increases, preferential sputtering of As and decomposition of AS203 increase and prevent formation of an
insulating film. No damage was detected by Rutherford backscattering spectrometry (RES) combined with ion channeling, in the substrate subjected to IBO below 1 keV.
A New 3D Multistring Code to Identify Compound Oxide Nanophase With Ion Channeling
James Douglas Bradley, Nicole Herbots, Robert Culbertson, Justin Shaw and Vasu Atluri
MRS Online Proceedings Library / Volume 996
a1 james.bradley@medtronic.com, Arizona St. University, Department of Physics, PO Box 871504, Tempe, AZ, 85287-1504, United States
a2 herbots@asu.edu, Arizona St. University, Physics and Astronomy, ASU Dept. of Physics and Astronomy, Box 1530, Tempe, AZ, 85287, United States
a3 robert.culbertson@asu.edu, Arizona St. University, Department of Physics, PO Box 871504, Tempe, AZ, 85287-1504, United States
a4 justin.shaw@nist.gov, NIST Magnetics Group, Magnetics Group, 325 Broadway, Mailstop 818.03, Boulder, CO, 80305, United States
a5 vasu.atluri@asu.edu, Arizona St. University, Department of Physics, PO Box 871504, Tempe, AZ, 85287-1504, United States
A new 3DMultiString computer code of Ion Beam Analysis (IBA) using 4He++ ion channeling combined with Nuclear... more A new 3DMultiString computer code of Ion Beam Analysis (IBA) using 4He++ ion channeling combined with Nuclear Resonance Analysis (NRA) is used to analyze controlled formation of order in continuous layers of silicon dioxide nucleated on (1×1) Si(100) via the Herbots-Atluri clean (U.S. patent 6,613,677 (9/3/2003)) in air at 300 K. In our most recent work, this new 3DMultiString simulations combined with IBA leads to the identification of a new two-dimensional nanophase of tetragonally distorted β-cristobalite SiO2 (annotated b-c SiO2) with a critical thickness of 2 nm from the (1×1) Si (100)/b-c SiO2 interface to the b-c SiO2 /amorphous SiO2 interface (annotated b-c SiO2/a-SiO2). 3DMultiString simulations of IBA data taken on this new b-c SiO2/(1×1) Si(100) interphase includes channeling along the three <100>, <110>, and <111> axes of Si (100) in combination 16OO(α, α)16O 3.045 MeV NRA to measure oxygen areal densities corresponding to nm-thick films. In this way, the critical thickness of the β-c SiO2 nanophase can be established as a function of oxygen coverage. This new 3DMultiSTRING computer code is derived from the original 3DSTRING program that originated at Bell Labs, NJ.coverage.
RBS STUDY OF THE EFFECT OF ARSENIC AND PHOSPHORUS INTERFACIAL SEGREGATION UPON THE SINTERING OF CONTACTS BETWEEN IMPLANTED POLYCRYSTALLINE SILICON AND ALUMINUM -SILICON(1%)
Nicole HERBOTS *, Maurice LOBET and Femand Van de WIELE
Microekxtronics Lab, Uniwrsite Catholique de Lmamin, 3, place du Levant. B - 1348 Louvain -la - Neuve, Belgium
Nuclear Instruments and Methods in Physics Research B7/8 (1985) 278-286 North-Holland, Amsterdam
The sintering behavior of the interface between Al :Si(l%) alloy and polycrystalline Si (poly-Si) was studied as a... more
The sintering behavior of the interface between Al :Si(l%) alloy and polycrystalline Si (poly-Si) was studied as a function of the poly-Si implantation dose by combining RBS, SEM, TEM and X-ray microanalysis. Two different N-dopants were used: arsenic and phosphorus. The dopants were implanted in the poly-Si layer and thermal annealing was used to obtain dopant segregation towards the poly-Si interfacea.
After sir&ring, two main effects were detected: (1) Al-Si eutectic phase precipitates and Si crystallites are formed at the interface. (2) The density of precipitates is a function of the implantation dose. For doses above 1 x lOI5 at./cm2. segregated arsenic and phosphorus are found to completely inhibit this precipitation process, provided that the segregation peak of the dopant profile is preserved before metallization.
Several conclusions can be drawn: for surface concentrations higher than 8~10’~ at./cm3, arsenic and phosphorus inhibit the precipitation of the Al-Si eutectic phase, and thus inhibit interactions between the films at the interface. Moreover, argon gas, usedfor sputtering deposition of aluminum, segregated at the poly-Si/Al: Si(l%) interface and may also inhibit the metal-semiconductor interdiffusion.
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