bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Paths of Oxide Precipitate Nucleation in Silicon
Authors: Kissinger G. , Dabrowski J. , Sattler Andreas , Müller Timo , von Ammon Wilfried
Published: March 2009

The coherent agglomeration of interstitial oxygen into single-plane and double-plane
plates can explain the two peaks in the M-shaped nucleation curves in Czochralski silicon. The
density of nucleation sites for the double-plane plates corresponds to the VO2 concentration. Ab
initio calculations have shown that the agglomeration of oxygen atoms in single-plane and doubleplane
plates is energetically favorable. These plates are under compressive strain. VO2
agglomeration plays only a minor role for modeling the M-shaped nucleation curves because of
prior homogenization treatments. It is of much higher impact if as-grown wafers are subjected to
nucleation anneals because of the higher vacancy concentration which was frozen in during crystal
cooling. This results in higher nucleation rates at higher temperatures.
Because the oxygen diffusivity below 700 °C is important for the nucleation rate and many
controversial results about the diffusivity in this temperature range were published, we have
analyzed the data from literature. We have demonstrated that the effective diffusivity of oxygen at
temperatures below 700 °C which corresponds to the quasi equilibrium dimer concentration is very
similar to the extrapolation from oxygen diffusivity at high temperature. The high effective
diffusivities from out-diffusion and precipitation experiments, and the somewhat lower effective
diffusivities from dislocation locking experiments are the result of an ongoing formation of fast
diffusing dimers because the equilibrium is disturbed as the result of the strongly increasing
difference in the diffusion length between interstitial oxygen and the fast diffusing dimer with
decreasing temperature.
Defect Engineering for SIMOX Processing
Authors: Kögler Reinhard , Mücklich A. , Anwand W. , Eichhorn F. , Skorupa Wolfgang
Published: March 2009

SIMOX (Separation-by-Implantation-of-Oxygen) is an established technique to
fabricate silicon-on-insulator (SOI) structures by oxygen ion implantation into silicon. The main
problem of SIMOX is the very high oxygen ion fluence and the related defects. It is demonstrated
that vacancy defects promote and localize the oxide growth. The crucial point is to control the
distribution of vacancies. Oxygen implantation generates excess vacancies around RP/2 which act
as trapping sites for oxide growth outside the region at the maximum concentration of oxygen at
RP. The introduction of a narrow cavity layer by He implantation and subsequent annealing is
shown to be a promising technique of defect engineering. The additional He implant does not
initiate oxide growth in the top-Si layer of SOI.
Hydrogen Interaction with Point Defects in the Si-SiO2 Structures and its Influence on the Interface Properties
Authors: Kropman Daniel , Mellikov E. , Kärner Tiit , Ugaste Ü. , Laas Tony , Heinmaa Ivo , Abru U. , Medvid Arthur
Published: March 2009

The type and density of the point defects that are generated in the Si surface layer during
thermal oxidation depend on the oxidation condition: temperature, cooling rate, oxidation time,
impurity content. Interaction between the point defects with extended defects and impurities affects
the SiO2 structure and Si-SiO2 interface properties. Hydrogen adsorption on n- and p- type wafers
is different. One possible reason for that can be the strength of the magnetic interaction between the
hydrogen and paramagnetic impurities of the adsorbent. The influence of point defects and
impurities may be diminished and the interface properties improved by an appropriate choice of the
oxidation conditions and postoxidation laser irradiation.
Investigation of the Hydrogen Transport Processes in Crystalline Silicon of n-Type Conductivity
Authors: Saad Anis M. , Velichko Oleg , Shaman Yu P. , Barcz Adam , Misiuk Andrzej , Fedotov A.K.
Published: March 2009

The silicon substrates were hydrogenated at approximately room temperature and
hydrogen concentration profiles vs. depth have been measured by SIMS. Czochralski grown (CZ)
wafers, both n- and p-type conductivity, were used in the experiments under consideration. For
analysis of hydrogen transport processes and quasichemical reactions the model of hydrogen atoms
diffusion and quasichemical reactions is proposed and the set of equations is obtained. The
developed model takes into account the formation of bound hydrogen in the near surface region,
hydrogen transport as a result of diffusion of hydrogen molecules 2 H , diffusion of metastable
complexes *
2 H and diffusion of nonequilibrium hydrogen atoms. Interaction of 2 H with oxygen
atoms and formation of immobile complexes “oxygen atom - hydrogen molecule” (O - H2 ) is also
taken into account to explain the hydrogen concentration profiles in the substrates of n-type
conductivity. The computer simulation based on the proposed equations has shown a good
agreement of the calculated hydrogen profiles with the experimental data and has allowed receiving
a value of the hydrogen molecules diffusivity at room temperature.
Mapping of Device Yield Relevant Electrical Si-Wafer Parameters
Authors: Niemietz Kathrin , Dornich Kay , Hahn Torsten , Helbig A. , Hellwig Stefan , Stegemann Karl Heinz , Niklas J.R.
Published: March 2009

With an innovative measurement technique termed “microwave detected
photoconductivity” (MDP) it is possible to investigate defects of silicon wafers contact less and
topographically by evaluating photoconductivity transients detected via microwave absorption.
Thus it is possible to obtain the electrical key parameters (e.g. diffusion length and lifetime) in a
contact less, non destructive and topographic way. The method is ideal for the investigation of
process induced defects as a function of different processing steps. The inhomogeneities of the
diffusion length map of the pure wafer correlate very well with the key parameter map of
photosensor devices. Even more details of process induced failures of devices can be detected in
detail with MDP. In general, the measurement conditions together with their evaluation can be
tuned to nearly ‘predict’ properties and production yield of final devices for a given chain of
processing steps.
Growth and Properties of Silicon Nanowires for Low-Dimensional Devices
Authors: Werner P.
Published: March 2009

The generation of semiconductor nanowires (NWs) by a “bottom-up” approach is of
technological interest for the development of new nanodevices. In most cases Si and SiGe
nanowires (NWs) are grown by molecular beam epitaxy (MBE) and by chemical vapor deposition
(CVD) on the base of the vapor-liquid-solid-mechanism (VLS). In both cases small metal droplets
act as a seed for the NW formation. The article mainly refers to the specific features of the MBE
growth. The application of metals related to the VLS growth concept (quite often gold droplets are
used) also causes several disadvantages of this approach, e.g., the formation of a metal wetting layer
on all surfaces, dislocations, and electric active point defects. Concerning the formation of devices,
technological steps, such as oxidation and doping of NWs, have to be considered. Specific
techniques have to be applied to investigate the properties of individual semiconductor NWs. Some
examples shall illustrate this topic.
Modification of Silicon Nanocrystals Embedded in an Oxide by High Energy Ion Implantation
Authors: Antonova I.V. , Gulyaev M.B. , Skuratov V.A. , Marin D.V. , Zaikina E.V. , Yanovitskaya Z.S. , Jedrzejewski J. , Balberg I.
Published: March 2009

Samples with layer of silicon nanocrystals embedded in SiO2 (the single phase Si content
in oxide ranged between 5 and 92 volume %) were subjected to high energy ion implantation.
Implantation-induced modifications of SiO2-ncSi properties discussed in this paper include a shift
of the major ncSi-related photoluminescence peak and intensification of the high-photon energy
peaks, that accompany the change in amount and type of the charge trapped on the nanocrystals. A
unified model is suggested for all these phenomena.
Hydrogenated Nanocrystalline Silicon Thin Films Studied by Scanning Force Microscopy.
Authors: Cavalcoli Daniela , Rossi Marco , Tomasi Andrea , Cavallini Anna , Chrastina Danny , Isella Giovanni
Published: March 2009

Hydrogenated nanocrystalline silicon for photovoltaic applications has been investigated.
Morphological properties, as well as electrical properties, have been investigated with high spatial
resolution by scanning force microscopy analyses (AFM, Atomic Force Microscopy and C-AFM
conductive AFM). A major problem regarding the electronic properties is to understand where the
current flows. The present contribution aims to clarify which of the material phases mainly
contributes to the conduction mechanism.
Phonon Confinement and Impurity Doping in Silicon Nanowires Synthesized by Laser Ablation
Authors: Fukata Naoki , Oshima T. , Okada N. , Matsushita S. , Tsurui T. , Chen J. , Sekiguchi Takashi , Murakami K.
Published: March 2009

The effect of phonon confinement and impurity doping in silicon nanowires (SiNWs)
synthesized by laser ablation were investigated. The diameter of SiNWs was controlled by the
synthesis parameters during laser ablation and the subsequent thermal oxidation. Thermal oxidation
increases the thickness of the SiNWs’ surface oxide layer, resulting in a decrease in their crystalline
Si core diameter. This effect causes a downshift and asymmetric broadening of the Si optical phonon
peak due to phonon confinement. Boron doping was also performed during the growth of SiNWs.
Local vibrational modes of boron (B) in silicon nanowires (SiNWs) synthesized by laser ablation
were observed at about 618 and 640 cm–1 by Raman scattering measurements. Fano broadening due
to coupling between discrete optical phonons and the continuum of interband hole excitations was
also observed in the Si optical phonon peak. These results prove that B atoms were doped in the
SiNWs.
Interstitial Carbon-Related Defects in Si1-xGex Alloys
Authors: Khirunenko Lyudmila I. , Pomozov Yu.V. , Sosnin Mikhail G. , Duvanskii A.V. , Torres Vitor , Coutinho J. , Jones R. , Briddon Patrick R. , Abrosimov Nikolay V. , Riemann H.
Published: March 2009

The interstitial carbon impurity (CI) vibrational modes in monocrystalline Si-rich SiGe
were investigated by Fourier Transform Infra Red spectroscopy and density functional modelling.
The two absorption bands of CI are found to be close to those in silicon, but show shifts in opposite
directions with increasing Ge content. The transversal mode band at 932 cm-1 shifts slightly to the
high frequency side, while the longitudinal mode at 922 cm-1 suffers a pronounced red-shift. Each
Ci-related band is found to consist of two components. An annealing of CI in Si1-xGex occures in
two stage. During the first stage (210-250 K) the main components of bands anneals and revealed
components grow in intensity. At T>250 K all components disappear. Two component structure of
bands is suppose most likely correspond to different combinations of Si and Ge atoms in the
neighbourhood of the carbon atom. The interstitial carbon defect was modelled by a supercell
density-functional pseudopotential method (AIMPRO) for alloys with 4.69% Ge concentration.
From energetics, it has been found that each Ge-C bond costs at least 0.4 eV in excess of a Si-C
bond. However, structures where Ge atoms are second neighbors to the C atom are marginally
bound, and may explain the two-component band structure in the absorption measurements. The
vibrational mode frequencies taken from several randomly generated SiGe cells produce the
observed opposite shifts for the transverse and longitudinal modes.
Terahertz Emission from Phosphor Centers in SiGe and SiGe/Si Semiconductors
Authors: Pavlov Sergeij G. , Hübers Heinz Wilhelm , Abrosimov Nikolay V. , Riemann H. , Radamson H.H. , Bekin N.A , Yablonsky A.N. , Zhukavin R.Kh. , Drozdov Y.N. , Shastin V.N.
Published: March 2009

Terahertz-range photoluminescence from silicon-germanium crystals and superlattices
doped by phosphor has been studied under optical excitation by radiation from a mid-infrared CO2
laser at low temperature. SiGe crystals with a Ge content between 0.9 and 6.5 %, doped by
phosphor with a concentration optimal for silicon laser operation, do not exhibit terahertz gain. On
the contrary, terahertz-range gain of ~ 2.3 - 3.2 cm-1 has been observed for donor-related optical
transitions in Si/SiGe strained superlattices at pump intensities above 100 kW/cm2.
X-Ray Characterization of the Lattice Perfection of Heteroepitaxial SIS Structures
Authors: Zaumseil P. , Weidner G. , Schroeder T.
Published: March 2009

The crystallographic structure of semiconductor - insulator - semiconductor (SIS) structures
consisting of a Si(111) substrate, Pr2O3 and Y2O3 insulating high-k materials, and Si cap layer
was characterized by a combination of X-ray pole figure measurement and conventional X-ray diffraction.
Oxide and Si cap layer were grown by molecular beam epitaxy and have the same 111 lattice
orientation as the substrate. It is shown that the oxide layers grow in a type B stacking orientation
only, while the epi-layer exhibits exclusively the same type A orientation as the substrate. A
small fraction of the epi-Si lattice was identified with 511 netplanes parallel to the surface. TEM
investigations identify these areas as structural defects between Si grains of differing stacking sequence.
Electroluminescence from ZnO/n+-Si Heterojunction
Authors: Ma Xiang Yang , Chen Pei Liang , Li Dong Sheng , Yang De Ren
Published: March 2009

The ZnO/n+-Si heterojunction has been fabricated via depositing nominally undoped ZnO
film by reactive sputtering on a heavily arsenic-doped (n+) silicon substrate. The sputtered ZnO film
was n-type in conductivity with an electron concentration of 1.0×1018 cm-3. The current-voltage
characteristics indicate that the ZnO/n+-Si heterojunction does not possess rectifying function. Under
the forward bias with the negative voltage applied on the n+-Si substrate, the heterojunction emits
ultraviolet and broad visible lights characteristics of near-band-edge and defect-related emissions of
ZnO, respectively. The EL mechanism has been tentatively explained in terms of the energy-band
diagram.
Metal Hard Mask Employed Cu/Low k Film Post Ash and Wet Clean Process Optimization and Integration into 65nm Manufacturing Flow
Authors: Lin Miao Chun , Wang Mei Qi , Lai Joe , Huang Ren , Weng Cheng Ming , Liao J.H. , Tang Jian She , Weng Ching Hwa , Lu Wei , Chen Han Wen , Lee John T.C.
Published: March 2009

As 65nm technology in mass production and 45nm technology under development, post etch ash and
cleaning faces new challenges with far more stringent requirements on surface cleanliness and
materials loss. The introduction and integration of new materials, such as metal hard mask, creates
additional requirements for wafer cleaning due to the occurrence of new defect modes related to metal
hard mask. We have optimized a post etch ash process and developed a novel aqueous solution (AQ)
based single wafer cleaning process to address these new defect modes. Physical characterization
results and process integration electrical data are presented in this paper.
Effect of SC-1 Treatment in Thermal Wall Oxide on Nanoscale STI Gap-Filling by O3/TEOS CVD
Authors: Lee Seung Cheol , Ryu Choon Kun , Park Sang Wook , Jin Gyu An , Kim Sang Deok , Yang Ki Hong , Kwak Sang Hyon , Lim Su Hyun , Kim Young Jun , Park Sun Mi , Jang Chul Sik , Park Sung Ki
Published: March 2009

The SC-1 treatment prior to the O3/TEOS CVD was a very effective method for gapfilling the nanoscale trench of the high aspect ratio by improving the adsorption of TEOS precursors onto the wall oxide. It was found that the interval duration after the SC-1 cleaning was a critical parameter for the contact angle and the gapfill performance of the O3/TEOS CVD.
Catalytic Combustion of Effluents from Methane-Based MCFC Device over Cordierite Supported Pd/La-Al2O3 Catalyst
Authors: Lee Jong Min , Hwang Young Kyu , Mamman Ajit Singh , Lee Sang Min , Hong Do Young , Ahn Kook Young , Chang Jong San
Published: March 2009

Influence of steam, loading amounts of Pd (viz., 0.7, 2.1, 5.4 wt %) and other
process parameters (viz. GHSV and temperature) on methane-based MCFC anodeeffluents
over Pd-based La2O3-Al2O3 supported on honeycomb substrate have been
investigated. TGA study reveals precise temperature of decomposition of Pd-O in
catalytic combustion at high temperature. An increase in methane conversion at elevated
temperature is attributable to decomposition of PdO to Pd active phase. The XRD
analysis of spent catalysts suggests that the reflections corresponding to PdO gradually
become weaker with increase in the Pd loading. The addition of 4% water in the feed
decreases the methane conversion due to the reversible reaction of PdO with water
adduct resulting in the formation of inactive Pd(OH)2 phase. However, the methane
conversion remains unaffected and increases monotonously with 100% water
concentration in the feed.
Formation of Nano M2X Particles by a Tempering in High Cr Ferritic/Martensitic Steel
Authors: Kim Sung Ho , Han Chang Hee , Ryu Woo Seog
Published: March 2009

The precipitation of nano Cr2N particles in high Cr FM steels has been studied. The nitrogen content of the FM steels was changed to form stable Cr2N particles. Tempering temperature was also changed from 500 oC to 800 oC to study the precipitation behavior of the Cr2N particles with the tempering temperature. The Cr2N particles remained as a stable phase at a higher tempering temperature by increasing the nitrogen content. The shape of these particle was a fine needle type which was very similar to V(C,N) particles. The size of some Cr2N particles was increased as the nitrogen content increased. But these precipitates were not dissolved or largely coarsened during a creep deformation at 600°C. So it seems that they may act as an effective obstacle against a dislocation glide during a creep deformation, thus contribute to an increase of the creep rupture strength in high Cr FM steels.
Nucleation of Intragranular Ferrite on B1-Type Non-Metallic Inclusions
Authors: Jin Hyung Ha , Shin Chan Sun , Lee Hu Chul , Kim Wheung Whoe
Published: March 2009

A nucleation of intragranular ferrite grains by B1-type non-metallic inclusions was
investigated using electron microscopes. Intragranular ferrite grains surrounding a TiN particle is
observed in Ti-containing steel. On the other hand, no intragranular ferrite nucleated on NbN and
ZrN. It is deduced that the NbN and the ZrN particle can not promote a nucleation of an
intragranular ferrite for their high interfacial energy with ferrite. The TiN particle which has the BN
relationship with the intragranular ferrite is an inclusion that effectively promotes an
intragranular ferrite nucleation. The acicular ferrite grains formed in the austenite grains were
trigged by the intragranular ferrite grain(s) formed around TiN.
Corrosion Behavior of Ceramic Dispersion Strengthened High-Cr Stainless Steel
Authors: Lee Gyoung Ja , Lee Sang Hoon , Hong Sung Mo , Han Byung Sun , Park Jin Ju , Lee Min Ku , Rhee Chang Kyu
Published: March 2009

In the present work, corrosion characteristics of ceramic dispersion strengthened (CDS)
high-Cr stainless steel (SS) has been investigated. For the preparation of CDS SS with uniformly
distributed reinforcements, TiC particles were mechanically activated with Cu powder by using
high-energy ball mill machine, and then Cu-coated TiC particles were mixed with molten SS.
Potentiodynamic polarization curves were experimentally measured on unmodified SS and CDS SS
in 0.05 M NaCl solution. The values of corrosion potential Ecorr, corrosion current io, pitting
potential Epit and polarization resistance Rp were quantitatively determined from the measured
potentiodynamic polarization curves. From the result, it is concluded that CDS SS exhibits higher
corrosion resistivity than unmodified SS.
Effect of Magnesium Addition on the Phase Transformation of α-Alumina Prepared from Route of Ammonium Aluminum Carbonate Hydroxide
Authors: Jung Young Mi , Kim Sang Woo
Published: March 2009

Effect of magnesium addition on rapid transformation of α-alumina prepared from route
of ammonium aluminum carbonate hydroxide during thermal heating and microwave radiation
heating was investigated. The phase transformation and the final particle size of the transient
alumina composite powder were significantly affected by amount of magnesium added in the
aluminum precursor during the microwave radiation heating in various environmental atmospheres.
Rapid transformation from γ- to α-phase was found in the magnesium added transient alumina by
microwave-assisted transformation and nano-sized α-alumina was obtained. When the 3 wt%
magnesium added ammonium aluminum carbonate hydroxide was heated by microwave radiation
under nitrogen atmosphere, the transformation temperature from γ- to α-alumina was considerably
lowered to 1000°C and the average particle size of 27.6 nm was attained for the α-alumina-spinel
composite powder.
Reduction Behavior of W and Cu Oxides Powder Mixture
Authors: Lee Seong , Noh Joon Woong , Kim Eun Pyo , Hong Moon Hee
Published: March 2009

The reduction behavior of WO3 and CuO powder mixture has been studied by using thermo-gravimetric(TG), X-ray diffraction, and scanning electron microscopic analyses. The powder mixture was manufactured by ball-milling. It was found that W coated W-Cu composite powders were formed when reducing the powder mixture under hydrogen atmosphere. The following reduction steps are suggested as a mechanism for the formation of W coated W-Cu composite powders: with increasing temperature, Cu is initially reduced from CuO and the reduction reactions of WO3 to WO2 via WO2.9 and WO2.72 are followed. The gas phase WO2(OH)2 is formed by the reaction of the WO2 and water vapor, and then WO2(OH)2 diffuses toward Cu surface and deposits on it as W by reducing reaction with environmental hydrogen gas. The formation mechanism of W coated W-Cu composite powders involving the gas phase transportation reaction has been confirmed by the model experiment conducted by using Cu plate and WO3 powder.
Formation of Lanthanum Hydroxide and Oxide via Precipitation
Authors: Kim So Jin , Han Won Kyu , Kang Sung Goon , Han Min Su , Cheong Young Hun
Published: March 2009

Lanthanum hydroxide and oxide were prepared by the precipitation method in an aqueous
medium at room temperature. The precipitate was examined using thermal analysis, X-ray diffraction
and Scanning Electron Microscopy to investigate the phase evaluation and the thermal
transformation by decomposition. The as-precipitated powder from the precipitation method was
hexagonal La(OH)3. The lanthanum hydroxide was decomposed to oxide in two-steps as La(OH)3 →
LaOOH + H2O and 2LaOOH → La2O3 + H2O.
Conductive Property of Carbon-Nanotube Dispersed Nanocomposite Coatings for Steel
Authors: Yang Yun Shik , Kim Myeong Jun , Lee Young Chul , Noh Si Tae
Published: March 2009

Nanostructured modification of polymers has opened up new perspective for multifunctional
materials. Carbon-nanotubes have the potential to increase the conductivity of their
composite, with improved or retaining mechanical performance.
This study focuses on the evaluation of the thermal and electrical conductivities of carbonnanotube
filled alkyd resins for steel coatings. Polymer/Carbon-nanotube nanocomposites have
been prepared by mixing commercial multiwall carbon-nanotubes with alkyd resins and by curing.
The thermal and electrical conductivities of carbon-nanotubes filled nanocomposite was found to be
increased comparing with the original resin without any fillers or with the resin with carbon-black
or carbon-nanofiber.
Preparation of Platinum-Ruthenium Nanoparticles on Graphite Nanofibers
Authors: Kim Seok , Park Soo Jin
Published: March 2009

Electroactivity of graphite nanofibers (GNFs)-supported PtRu particles was examined for
their application as DMFCs anode. In this work, composites of PtRu nanoparticles of 2-8 nm size
and graphite nanofibers were prepared by the electrodeposition methods. As a result, the methanol
oxidation current for graphite nanofibers-supported PtRu catalysts was investigated by changing a
deposition time. The electroactivity could be attributed to the particle size, particle dispersion
ability, and deposition level.
Methane Storage on Surface Modified Activated Carbons
Authors: Yun Seok Min , Kim Ju Wan , Jin Hang Kyo , Kim Young Ho , Lee Young Seak
Published: March 2009

In this study, methane gas absorption ability of activated carbon (AC) with surface
functional group effect, was evaluated after nitric acid and urea treatment of AC surface. Specific
surface area and pore distribution of AC were studied through nitrogen absorption isotherm at 77 K.
Micro pore volume was calculated through H-K method. Absorbed methane amount was evaluated
through volumetric method at room temperature by using auto absorption apparatus. Absorbed
methane amount of AC was found to increase with specific surface area increase. Correlation
proposed between the methane absorption amount and surface nature indicates that the surface
nature plays an important role on the absorption amount at a given temperature.
Development and Application of Irradiation Technology in HANARO
Authors: Choo Kee Nam , Kim Bong Goo
Published: March 2009

A material capsule system including a main capsule, a fixing, a control, a cutting, and a
transport system was developed for an irradiation test of non-fissile materials in HANARO. This
capsule system has been actively utilized for the various material irradiation tests requested by users
from research institutes, universities, and the industries. Based on the accumulated irradiation
experience and the user’s sophisticated requirements, the instrumented capsule technologies for a
more precise control of the irradiation temperature and fluence of a specimen were developed in
HANARO. 6,000 specimens from domestic research institutes, nuclear industry companies and
universities, were irradiated in HANARO for 54,000 hours by using the developed capsule irradiation
system. Recently, development of new instrumented capsule technologies for an IP/OR irradiation
test and a high temperature irradiation test has been performed in HANARO for relevant ongoing
R&D for the international Gen IV Program. New irradiation technologies are also under development
for the production of new functional materials including superconductor and optical/electrical
materials.
Delamination Buckling of Kevlar and Twaron Stitched Glass\Epoxy Composite Laminates by Experiments
Authors: Parlapalli Madusudhanan R. , Soh Kwok C. , Shu Dong Wei
Published: March 2009

In the present paper, effects of through-the-thickness stitching of delaminated glass/epoxy
composite laminates with two different types of aramid threads, Kevlar® and Twaron® threads, on the
buckling loads are studied. The buckling loads are predicted based on the Southwell, Vertical displacement
and Membrane strain plot methods from the experimental data. Flexural modulus of the stitched and
unstitched glass/epoxy composite laminates, knot tensile strength of Kevlar® and Twaron®
stitching threads are obtained experimentally. From the Southwell, Vertical displacement and
Membrane strain plot methods it is observed that stitching either by Kevlar® or Twaron® threads
is effective in improving the buckling strength of glass/epoxy composite laminates when the
delamination length is greater than 0.5L, L is the length of the laminate.
Growth of (Zr,Ti)N Thin Films by Ion-Assisted Dual D.C. Reactive Magnetron Sputtering
Authors: Hodak Satreerat K. , Seppänen T. , Tungasmita Sukkaneste
Published: March 2009

The ternary nitride (Zr,Ti)N thin films were grown on silicon substrates by ion-assisted dual d.c. reactive magnetron sputtering technique. The substrates were exposed to ion bombardment with varying kinetic energy in the range of 3-103 eV under N/Ar ratio of 1:3. The (Zr0.6Ti0.4)N was formed at all growth conditions. X-ray diffraction measurement indicates the presence of (Zr,Ti)N solid solution with (111) and (200) preferred orientations. The (200) orientation is only present when the films are grown at ion bombardment energies higher than 33 eV. Optimum conditions for film growth produced hardness in the range of 27-29 GPa.
Sprayed-On Polymer as Concrete Spall Shield
Authors: Lim Bryan , Hong Pei Jun
Published: March 2009

Concrete when subjected to a blast loading from a close-in detonation will experience
spalling due to formation of tension waves on the opposite face of the concrete panel. The spalled
concrete may be ejected at high velocity causing undesirable effects to occupants. Tests using 1/2kg
TNT blocks were conducted on 100mm thick concrete panels to study the effects of spalling and
whether the spalled materials can be arrested using a sprayed-on polymeric coating. From the tests,
it was observed that without the sprayed-on polymeric coating, extensive spalling occurred.
However, with just a 3-4mm thick layer of sprayed-on polymer, the spalled materials were arrested
and contained. Numerical models of the reinforced concrete slab were created using Autodyn 2D
and the results of the simulation were compared to observations from the tests. There was good
correlation between the test results and the simulation results as the size of the crater, both front and
back, on the concrete slab were rather similar.
Sonochemical Synthesis of Poly (Methyl Acrylate)
Authors: Jothi Rajan M.A. , Mathavan T. , Vivekanandam T.S. , Umapathy S. , Ganesan V. , Okram G.S. , Soni Ajay
Published: March 2009

Polymers are prepared by various methods. The method of preparation plays an important role in deciding many of the physical properties of polymers. In this work Poly (Methyl Acrylate), PMA, is synthesized by free radical addition polymerization in the presence a monomer, an initiator under the influence of ultrasound. Methyl Acrylate (E-Merck, India) of proper strength is mixed with aqueous sodium peroxodisulphate solution of known strength and the time of passage of ultrasound is varied in steps of 30 minutes and 10 samples of solid PMA are obtained for 10 different periods of passage of ultrasound. Solid PMA samples are purified and air-dried under clean environment. TGA, DTA measurements are done on all the 10 PMA samples. The thermal stability of PMA with the change in the time of passage of ultrasound is discussed quantitatively. The thermal stability of PMA, synthesized sonochemically shows better results over the thermal method of synthesis. However in this paper we report the measurements made on PMA samples synthesized at 30 and 300 minutes sonication periods respectively.
Skin-Core Micro-Structure and Surface Orientation of Carbon Nanotube Composites by Injection Molding Process
Authors: Li Zhi Fei , Luo Guo Hua , Zhou Wei Ping , Wei Fei
Published: March 2009

Multi-walled carbon nanotube (MWNT) was filled into poly (ethylene terephthalate) (PET) matrix and MWNT/PET composite was prepared by injection molding process. The microstructure and electrical conductive property were investigated carefully. After injection molding, the electrical conductivity of injected sample decreased sharply because of the orientation of CNT due to strong shearing force. The electrical conductive network of CNT had been destroyed after orientation of CNT. Because of the difference of shearing rate between the surface and the body center during the injection molding process, a skin-core structure emerged. Near the surface, the injected sample has higher degree of orientation of CNT and higher electrical resistance.
Synthesis of Nano-Sized Co-Sb Compounds through Solvothermal Routes
Authors: Yang L. , Hng H.H. , Sun T. , Cheng H. , Ma Jan
Published: March 2009

Skutterudite materials have received great attention because their promising properties
for thermoelectric (TE) applications. Among the family of skutterudites, CoSb3 has been intensively
investigated due to its large electrical conductivity and Seebeck coefficient. However, its thermal
conductivity is too high to make it an effective TE material. Nanostructuring of CoSb3 has the
desirable effects of reducing its lattice thermal conductivity as the point imperfections or grain
boundaries can scatter phonons (heat carrier) more effectively than electrons (charge carrier). In this
study, nanostructured CoSb3 was synthesized by solvothermal routes using CoCl2·6H2O and SbCl3
as precursors dissolved in anhydrous ethanol with the reaction temperature kept at 240°C. In
addition to the CoSb3 phase, other Co-Sb compounds were also formed during the reaction process.
In this paper, we investigated the effects of processing parameters, such as concentration of
CoCl2·6H2O, SbCl3 and NaBH4 in ethanol and thermal duration of solvothermal synthesis, on the
yield of CoSb3 phase.
Three-Body Abrasive Wear Behaviour of Fiber Reinforced Vinyl Ester Composites
Authors: Suresha B. , Jayaraju T. , Sadananda Rao P.R. , Ismail Mohammed , Shivakumar Kunigal N.
Published: March 2009

Fiber reinforced polymer composites are generally known to possess high strength and attractive wear resistance in dry sliding conditions. The behaviour of such composites performing in abrasive wear situations needs a proper understanding. Hence, in the present work of the three-body abrasive wear behaviour of two dimensional stitched carbon fabric, E-glass woven fabric and three dimensional E-glass woven fabric reinforced vinyl ester composites was investigated. Three-body abrasive wear tests were conducted using rubber wheel abrasion tester (RWAT) under different abrading distances at two loads, wherein the wear volume loss were found to increase and that of specific wear rate decrease. The results indicate that the type of fabric in vinyl ester have a significant influence on wear under varied abrading distance/loads. Further, it was found that carbon fabric reinforced vinyl ester composite exhibited lower wear rate compared to E-glass woven fabric reinforced vinyl ester composites. The worn surface features, as examined through scanning electron microscope (SEM), show higher levels of broken glass fiber in two dimensional glass woven fabric reinforced vinyl ester composite compared to carbon fabric and three dimensional glass fabric reinforced vinyl ester composites.
Low Temperature Kinetics of In-Cd Solid Solution Decomposition
Authors: Pal-Val P.P. , Pal-Val L.N. , Ostapovets A.A. , Vanek P.
Published: March 2009

An influence of Cd content on the kinetics of a spontaneous low-temperature structure
transformation in In-rich In - Cd alloys has been investigated using acoustic, resistivity and DSCtechniques.
It is established that increase of the concentration of Cd leads to an essential increase of
a driving force of the transition that results in an increase of the transition rate and in decrease of the
relaxation time. The low-temperature instability of acoustic, resistivity and thermal properties is
caused presumably by a decomposition of the solid solution that has features of a phase transition of
the 1st order. The main empirical activation parameters of the transformation are derived. The
activation energy amounts to U0 = 0.43 eV, the attempt period is τ 0 =5 × 10-9 s. The probable border
of the decomposition in the phase diagram of the In-Cd system is established.
Diffusion of Light Elements in BCC, FCC and HCP Metals
Authors: Vykhodets V.B. , Kurennykh Tatiana Eugenievna , Lakhtin Aleksandr S. , Fishman Anatoly Yakovlevich
Published: March 2009

The mechanisms of formation of activated states upon diffusion of impurity interstitial atoms in metals have been identified, which allows formulation of the theoretical criterion for reliability of corresponding experimental data. This criterion is valid for almost all experimental results gained using precise techniques for bcc, fcc, and hcp metals. In case of hydrogen, oxygen, and nitrogen, most adequate are the models of potential diffusion barrier that are based on the elasticity theory. For carbon and boron, a less energy-taking mechanism is realized which involves the electron system rearrangement in a crystal during the diffusion jump. The accuracy of the theoretical criterion is in line with the capacities of modern precision techniques.
Effect of Cooling Rate on Structural and Chemical Microheterogeneity of IN 738LC Nickel Based Superalloy
Authors: Dobrovská Jana , Dočekalová Simona , Dobrovská Věra , Stránský Karel
Published: March 2009

The paper deals with the effect of cooling rate on solidification behavior of IN 738LC
nickel based superalloy and on resulting structural and chemical microheterogeneity of this alloy.
Samples taken from as-received state were heated with controlled ramp rates (1, 5, 10 and
20 °C min-1). Immediately after melting they were cooled with the same controlled ramp rate with
the help of the laboratory experimental system SETARAM SETSYS 18TM TG/DTA/TMA. Then
the microanalysis of minority phases was conducted with use of X-ray spectroscopy and
microstructure of the individual samples was documented by scanning electron microscopy.
Chemical microheterogeneity was determined on the basis of measured concentration data of
selected elements (Al, Ti, Cr, Co, Ni, Nb, Mo, Ta and W) in representative areas of the individual
samples structure.
Is the Compensation Effect a Phase Transition?
Authors: Lejček Pavel
Published: March 2009

The compensation effect, i.e. the linear dependence between characteristic enthalpy and entropy, has been frequently described in many fields of science and its close relationship to a phase transition is often assumed. In this paper it is shown for example of grain boundary segregation that the compensation effect principally differs from the phase transition although they can occasionally occur at the same temperature.
Formation of NiAl Shape Memory Alloy Thin Films by a Solid-State Reaction
Authors: Myagkov V.G. , Bykova L.E. , Zharkov S.M. , Bondarenko G.N.
Published: March 2009

NiAl shape memory alloy thin films have been fabricated by a solid-state reaction in Al/Ni bilayer films. Two kinds of synthesis have been used. The first one consists in heating an Al/Ni bilayer film system to temperatures above 480 K. The second one implies the successive deposition of nickel and aluminum films onto a substrate with a temperature above 480 K. Regardless of a kind of the solid-state synthesis, the films obtained reveal a two-way shape memory effect. It is supposed that the solid-state reaction in Al/Ni bilayers starts at a temperature AS of the reverse of the martensitic transition in NiAl alloy. This indicates that the NiAl shape memory alloy thin films can be formed directly during the synthesis without need for lengthy heat treatment.
Martensitic Transformation Behavior and Shape Memory Effect of an Aged Ni-rich Ti-Ni-Hf High Temperature Shape Memory Alloy
Authors: Meng Xiang Long , Fu Yu Dong , Cai Wei , Zhang J.X. , Li Qing Fen , Zhao Lian Cheng
Published: March 2009

The martensitic transformation behavior and shape memory effect (SME) have been
investigated in a Ni-rich Ti29.6Ni50.4Hf20 high temperature shape memory alloy (SMA) in the present
study. After aging, the transformation temperatures of Ti29.6Ni50.4Hf20 alloy increase obviously due to
the precipitation of (Ti,Hf)3Ni4 particles. And the transformation sequence changes from one-step to
two-step. When the experimental alloy is aged at different temperatures for 2h, the transformation
temperatures increase rapidly with increasing the aging temperature and then change slightly with
further increasing the aging temperature. Most of the martensite variants preferentially oriented in the
aged Ti29.6Ni50.4Hf20 alloy. The aged Ti29.6Ni50.4Hf20 alloy shows the better thermal stability of
transformation temperatures than the solution-treated one because the precipitates depress the
introduction of defects during thermal cycling. In addition, the proper aged Ti29.6Ni50.4Hf20 alloy also
shows the larger SME than the solution-treated one since the precipitates strengthen the matrix
strongly.
Identification and Characterization of Phase Transformations by the Resistivity Measurements in Mg-RE-Mn Alloys
Authors: Stulíková Ivana , Smola Bohumil
Published: March 2009

The response of the relative resistivity changes to the isochronal annealing was measured in MgSc, MgScMn and MgYNdScMn alloys. The derivatives of the annealing curves were fitted by Gaussian functions to determine and separate the temperature ranges of the phase transformations taking place. The Austin-Rickett kinetics is argued to justify this procedure for diffusion driven transformations. TEM observation verified the conclusions drawn from the procedure.
Atomistic Simulations of Copper Precipitation and Radiation Induced Segregation in α-Iron
Authors: Soisson Frédéric , Fu Chu Chun
Published: March 2009

We present Monte Carlo simulations of the first stages of the coherent precipitation of Cu
in α-Fe during thermal ageing and under irradiation. The simulations are based on a diffusion model
by vacancy and self-interstitial jumps, the parameters of which are fitted on ab initio calculations.
The simulations of precipitation kinetics during thermal ageing are compared with experimental
ones. They reveal that precipitates containing up to several tens of atoms can be much more mobile
than individual copper atoms, due to the trapping of vacancies in Cu. Monte Carlo simulations are
also used to analyze the coupling between fluxes of point defects and Cu which occurs under
irradiation and the possible resulting radiation induced segregation phenomena.
Morphological Evolution of Intragranular Void under the Thermal-Stress Gradient Generated by the Steady State Heat Flow in Encapsulated Metallic Films: Special Reference to Flip Chip Solder Joints
Authors: Ogurtani Tarik Omer , Akyildiz Oncu
Published: March 2009

The morphological evolution of intragranular voids induced by the surface drift-diffusion
under the action of capillary forces, electromigration (EM) forces, and thermal stress gradients
(TSG) associated with steady state heat flow is investigated in passivated metallic thin films via
computer simulation using the front-tracking method. As far as the device reliability is concerned,
the most critical configuration for interconnect failure occurs even when thermal stresses are low if
the normalized ratio of interconnect width to void radius is less than certain range of values (which
indicates the onset of heat flux crowding). This regime manifests itself by the formation of two
symmetrically disposed finger shape extrusions (pitchfork shape slits) on the upper and lower
shoulders of the void surface on the windward side. The void growth (associated with
supersaturated vacancy condensation) on the other hand inhibits anode displacement but enhances
cathode and shoulder slit velocities drastically, which causes lateral spreading.
Hydrogen Storage in MgH2 Matrices: An Ab-Initio Study of Mg-MgH2 Interface
Authors: Giusepponi Simone , Celino Massimo , Cleri Fabrizio , Montone Amelia
Published: March 2009

We studied the atomic-level structure of a model Mg-MgH2 interface by means of the
Car-Parrinello molecular dynamics method (CPMD). The interface was characterized in terms of
total energy calculations, and an estimate of the work of adhesion was given, in good agreement
with experimental results on similar systems. Furthermore, the interface was studied in a range of
temperatures of interest for the desorption of hydrogen. We determined the diffusivity of atomic
hydrogen as a function of the temperature, and give an estimate of the desorption temperature.
First-Principles Calculations of the Atomic and Electronic Structures in Au-Pd Slab Interfaces
Authors: Taguchi Noboru , Tanaka Shingo , Akita Tomoki , Kohyama Masanori , Hori Fuminobu
Published: March 2009

We performed first-principles calculations using the projector augmented-wave (PAW)
method for Au/Pd slab interface models. The calculations of relaxed configurations and energies for
the thin Pd layers (3 layers) stacking on Au (111) and Au (100) slabs with an epitaxial relationship
represent that Pd overlayers have a lateral expansion in both cases. This trend is in good agreement
with experimental results for Pd/Au slabs and Au-Pd core-shell nanoparticles, obtained by electron
microscopy, X-ray diffraction, and positron annihilation. In addition, an intermixing configuration
near the Au-Pd interface was shown to be more stable than the binary separated one.
In-Plane Rotated Crystal Structure in Continuous Growth of Bismuth Cuprate Superconducting Film
Authors: Kaneko Satoru , Akiyama Kensuke , Ito Takeshi , Hirabayashi Yasuo , Funakubo Hiroshi , Yoshimoto Mamoru
Published: March 2009

Bismuth cuprate superconductor has a unique structure called a structural modulation
(supercell, SC) consisting of modulated several unit cells. Strain induced by multilayered structure
increases the intensity of SC modulation, while an oxygen deficient sample shows expansion of SC
size. In this study, as opposed to the multilayer strain, by preparing samples with thick film
thicknesses the effect of strain on crystal structure was investigated including SC structure. Epitaxial
growth was verified by x-ray diffraction, and the thicker film showed other epitaxial phase rotated 32°
around the surface normal with respect to the initial epitaxial phase. The SC size estimated by x-ray
reciprocal space mapping was double the size of the initial epitaxial phase. Interestingly, the initial
epitaxial phase became a dominant structure after further deposition. In order to evaluate the different
SC size and SC modulation, a new index related with an incline of the modulation vector was
proposed.
Physics Mechanisms Involved in the Formation and Recrystallization of Amorphous Regions in Si through Ion Irradiation
Authors: Santos Iván , Marqués Luis Alberto , Pelaz Lourdes , Lopez Pedro , Aboy María
Published: March 2009

We focus this work on multi-scale modeling of the ion-beam-induced amorphization and
recrystallization in Si, although our scheme can be applied to other materials. We use molecular
dynamics to study the formation mechanisms of amorphous regions. We have observed that along
with energetic ballistic collisions that generate Frenkel pairs, low energy interactions can produce
damage through the melting and quenching of target regions. By quantifying these results, we have
developed an improved binary collision approximation model which gives a damage description
similar to molecular dynamics. We have successfully applied our model to ion and cluster
implantations. In order to define the energetic of defects in a more computationally efficient Kinetic
Monter Carlo code, we have used molecular dynamics results related to the recrystallization
behavior of local amorphous regions. The combination of all these simulation tools, molecular
dynamics (fundamental studies of damage formation and recrystallization), improved binary
collisions (including ballistic and melting-related damage) and Kinetic Monte Carlo (for efficient
defect kinetics modeling during the implantation and the subsequent annealing), allows us to model
the effect of ion mass, beam current and implant temperature on the amount and morphology of
residual defects in Si.