bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in Structural Characterization of Thin Film Nanocrystalline Silicon for Photovoltaic Applications
Authors: Le Donne Alessia , Binetti Simona , Isella Giovanni , Pichaud Bernard , Texier Michael , Acciarri Maurizio , Pizzini Sergio
Published: March 2009

The knowledge and control of the structural and morphological properties of
nanocrystalline silicon is a fundamental requisite for its proper application in photovoltaics. To this
purpose, nanocrystalline silicon films grown by Low Energy Plasma Enhanced Chemical Vapour
Deposition (LEPECVD) technique on different kinds of substrates were submitted to a systematic
characterization using Raman spectroscopy, X-ray diffraction (XRD) and high-resolution
transmission electron microscopy (HRTEM). The results showed that the nature of the film
substrate induces deep changes in the structural properties of the deposited films. The importance of
a Raman in–depth analysis for an accurate determination of the sample structure has been also
demonstrated.
Diffusion and Activation of Ultra Shallow Boron Implants in Silicon in Proximity of Voids
Authors: Marcelot O. , Claverie A. , Alquier Daniel , Cayrel Frédéric , Lerch Wilfried , Paul Silke , Rubin L. , Raineri Vito , Giannazzo Filippo , Jaouen H.
Published: March 2009

We have designed a set of experiments in which a controlled supersaturation of vacancies
can be maintained constant during annealing of a boron implant. In presence of voids, a remarkable
reduction of boron diffusivity is observed and, for low fluence B implantation, TED can be totally
suppressed. We show that the presence of nanovoids in the B implanted region is not a prerequisite
condition for the reduction of B diffusivity. Large voids located at more than 100 nm apart from the
B profile still show the same effect. Small voids can also be used to increase the activation of boron.
All these results are consistent with the hypothesis that, during annealing, vacancies are injected
from the voids region towards the Is rich region in the implanted region where they massively
recombine. Finally, we show that BICs cannot be simply dissolved by injecting vacancies into the
region where they stand.
Radiation-Induced Defect Reactions in Cz-Si Crystals Contaminated with Cu
Authors: Markevich Vladimir P. , Peaker Anthony R. , Medvedeva I.F. , Gusakov Vasilii E. , Murin L.I. , Svensson Bengt Gunnar
Published: March 2009

The influence of Cu contamination on radiation-induced defect reactions in n-type
Czochralski-grown silicon (Cz-Si) crystals has been studied by means of the Hall effect technique,
deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS with supporting
theoretical modeling of defects.
It is found that the contamination of Cz-Si samples with Cu does not influence significantly the
energy spectrum and introduction rates of the principal electrically active defects induced by
electron irradiation. The vacancy-oxygen (VO) centre, divacancy (V2) and a complex consisting of
a silicon self-interstitial with the oxygen dimer (IO2) are found to be the dominant radiation-induced
defects in Cu-contaminated samples as well as in uncontaminated ones. An isochronal annealing
study has shown that the presence of Cu affects the annealing behaviour of the vacancy-related
defects. In Cu-doped samples the VO centre disappears upon annealing at significantly lower
temperatures (175-250°C) compared to those of the VO disappearance in the uncontaminated
samples (300-375°C). The disappearance of the VO centres in the Cu-doped samples occurs
simultaneously with an anti-correlated introduction of a defect with an energy level at about Ec-
0.60 eV. It is suggested that this defect is formed by the interaction of a mobile Cu atom with the
VO complex. According to results of quantum-chemical modelling, in the most stable
configuration of the Cu-VO defect a Cu atom occupies a tetrahedral interstitial position nearest to
the elongated Si-Si bond of the VO centre. The presence of the Cu atom is found to result in the
further elongation of the Si-Si bond and a shift of the VO acceptor level to the middle of the gap.
The annealing behaviour of V2 has also been found to be different in the irradiated Cu-doped
samples compared to that in the uncontaminated ones. The most probable reason for this difference
is an interaction of mobile Cu atoms with di-vacancies. An energy level at about Ec-0.17 eV has
been tentatively assigned to a complex consisting of a Cu atom and a di-vacancy.
Origination and Properties of Dislocations in Thin Film Nitrides
Authors: Strunk Horst P.
Published: March 2009

Epitaxial group-III nitride films, although in single crystalline form, contain still a large
number of threading dislocations. These set limits to performance and lifetime of devices, notably
to high power structures like lasers. The strategy in material development was and will be (at least
until lattice-matched substrates become available) to reduce the dislocation densities. The present
contribution elaborates on possible dislocation origination mechanisms that determine the
population of dislocations in the epitaxial layers. These mechanisms can be controlled to a certain
degree by proper deposition procedures. The achieved dislocation populations then determine the
processes that can reduce the dislocation densities during growth of the epitaxial layers. The mutual
annihilation of threading dislocations is rather efficient although affected by the glide properties of
the growing epitaxial crystal and the thermal stresses during the cooling down after growth.
Evaluation of Surface Passivation Layers for Bulk Lifetime Estimation of High Resistivity Silicon for Radiation Detectors
Authors: Rafí J.M. , Cardona-Safont L. , Zabala M. , Boulord C. , Campabadal F. , Pellegrini G. , Lozano M. , Simoen Eddy , Claeys Cor
Published: March 2009

In order to identify an appropriate low-temperature surface passivation that could be used
for bulk lifetime estimation of high resistivity (HR) (> 1 k·cm) silicon for radiation detectors,
different passivating layers were evaluated on n-type and p-type standard Czochralski (CZ), HR
magnetic CZ and HR float zone (FZ) substrates. Minority carrier lifetime measurements were
performed by means of a μW-PCD set-up. The results show that SiNx PECVD layers deposited at
low temperatures (≤ 250°C) may be used to evaluate the impact of different processing steps and
treatments on the substrate characteristics for radiation detectors. First results are obtained about a
preliminary thermal treatment experiment to evaluate the thermal stability of the passivating layers,
as well as the potential impact of the generation of thermal donors on minority carrier lifetime.
Observation of Leakage Sites in High-k Gate Dielectrics in MOSFET Devices by Electron-Beam-Induced Current Technique
Authors: Sekiguchi Takashi , Chen J. , Takase Masami , Fukata Naoki , Umezawa Naoto , Ohmori Kenji , Chikyo Toyohiro , Hasunuma Ryu , Yamabe Kikuo , Inumiya Seiji , Nara Yasuo
Published: March 2009

We have succeeded in imaging the leakage sites of hafnium silicate gate dielectrics of
metal-oxide-semiconductor field-effect transistors (MOSFETs) by using electron-beam-induced
current (EBIC) method. Leakage sites of p-channel MOSFETs were identified as bright spots under
appropriate reverse bias condition when the electron beam energy is high enough to generate
carriers in the silicon substrate. Most of the leakage sites were observed in the peripheries of
shallow trench isolation. These results suggest that some process induced defects are the cause of
leakage in these MOSFETs. Our observation demonstrates the advantage of EBIC characterization
for failure analysis of high-k MOSFETs.
New Opportunities to Study Defects by Soft X-Ray Absorption Fine Structure
Authors: Boscherini Federico , De Salvador D. , Bisognin G. , Ciatto G.
Published: March 2009

X-ray absorption fine structure can determine the local structure of most atoms in the
periodic table. The great recent improvements in the performance of synchrotron radiation sources
and techniques and advances in the simulations of the spectra have opened new opportunities,
especially in the study of dilute systems in the soft X-ray range. In this contribution we will show
some recent results that demonstrate how semiconductor physics may greatly benefit from such
progress. In fact, doping or alloying of semiconductors with light elements, that have K absorption
edges in the soft X-ray range, is widely employed to tune semiconductor properties. X-ray
absorption fine structure investigations on such systems can give an important contribution towards
the understanding and optimization of technological processes.
Deep Level Transient Spectroscopy of Ultra Shallow Junctions in Si Formed by Implantation
Authors: Mitromara Niki , Evans-Freeman J.H. , Duffy Ray
Published: March 2009

We have carried out DLTS in highly doped p+n Ultra Shallow Junctions (USJ) in Si
formed by ion implantation. The samples were implanted either with a 10keV or a 5keV B implant
at a dose of 5*1015cm15. The 10keV sample was also implanted with P and the 5keV samples were
implanted with P and increasing doses of As to simulate an USJ in an n-well. Due to the high P
and/or As implant doses, it was observed that a band offset also exists between the n-type implanted
region and the n-type starting material. Therefore these samples contain another depletion region
apart from the expected p+n depletion region. However, the electric fields in these regions act in
opposite directions assisting the profiling of different regions after careful selection of biasing
conditions. A deep state is observed in the n-type region at EC-0.34eV which has a complex Laplace
DLTS signature, which has arisen due to the implantation process.
Mono- and Polycrystalline Silicon for Terahertz Intracenter Lasers
Authors: Pavlov Sergeij G. , Hübers Heinz Wilhelm , Abrosimov Nikolay V. , Riemann H.
Published: March 2009

The performance of optically pumped terahertz silicon lasers with active media made
from mono- and polycrystalline silicon doped by phosphorus has been investigated. The
polycrystalline silicon samples consist of grains with a characteristic size distribution in the range
from 50 to 500 m. Despite of significant changes of the principal phonon spectrum and increased
scattering of phonons at grain boundaries, the silicon laser made from polycrystalline material has a
laser threshold and an operation temperature only slightly worse than that of monocrystalline silicon
lasers.
Characterization of SiO2/Si Interface by Cathodoluminescent Method
Authors: Zamoryanskaya M.V. , Sokolov V.I.
Published: March 2009

The local cathodoluminescence is used to study the point defects and their depth
distribution in silicon oxide and silicon. The defects formed by two-coordinate silicon (Si=Si),
oxygen vacancies (Si-Si, Si-Si-Si), non-bridgen oxygen (-O.), amorphous silicon and silicon
nanoclusters have characteristic emission bands. High sensibility of cathodoluminescence method
permits to study natural silicon oxide film, thin silicon oxide and silicon layers near the interface. In
this paper an influence of the silicon type on the properties of SiO2/Si interface is discussed. It is
shown that the quality of SiO2/Si interface depends not only on the technology process but on the
silicon type and activator concentration. A high boron content in silicon leads to an increase of
point defects concentration in silicon oxide and sometimes to an appearance of Si nanoclusters near
the interface in the layer with 10-20 nm thickness. The concentration of intrinsic defects near the
silicon oxide – n-silicon interface depends also on phosphorous concentration. But in this case low
concentration of activator leads to a presence of high content of intrinsic defects in the first
monolayers of silicon oxide and to a dramatical decrease of a content of these defects in films with
thickness of more that 10 nm. On the contrary, the high concentration of activators leads to low
content of intrinsic defects near the interface and a rise of its content in the film with thickness more
that 10 nm.
Very First Relaxation Steps in Low Temperature Buffer Layers SiGe/Si Heterostructures Studied by X-Ray Topography
Authors: Burle Nelly , Pichaud Bernard , Vdovin V.I. , Rzaev M.M.
Published: March 2009

First relaxation stages in Si1-x Gex layers on Si substrates are induced by annealing of
metastable, low-temperature buffer layer samples and observed by X-ray topography (XRT). This
method allows observing large area (several square millimetres) of a sample and reveals very low
densities of defects, located in the layer as well as in the substrate. It allow to follow the evolution
of the very first steps of the relaxation, starting with dislocation crosses which were characterized
and evolving to misfit dislocation network by very low increases of thermal budget. It is proposed a
nucleation mechanism of these crosses based on Frank loops due to point defects condensation
which can transform locally in glide dislocations under the influence of the biaxial stress in the film.
Configuration of DV Complexes In Ge: Positron Probing of Ion Cores
Authors: Arutyunov N.Yu. , Emtsev Valentin V. , Sayed E. , Krause-Rehberg Reinhard
Published: March 2009

Angular correlation of annihilation radiation technique (ACAR) has been used for
studying a microstructure of the vacancy-group-V-impurity complexes (DV) formed by irradiation
with 60Co γ – rays at Tirr. ≈ 280K in oxygen-lean n-Ge doped with group-V-impurity atoms As, Sb,
and Bi. The probability of annihilation of positrons with the core electrons of DV complexes to be
reconstructed from ACAR spectra has been analyzed on the basis of Chapman-Kolmogorov
formalism; the Coulomb repulsion is proved to regulate the penetration of a positron into Ge4+ and
D5+ ion cores. In passing from AsV to SbV and BiV complexes the ion cores D5+ are found to
contribute more effectively to the probability of the positron annihilation in the core region. These
data correlate well with the augmentation of the entropy of ionization (4S ~ 2,9 ÷ 4,2K) observed
by means of capacitance transient techniques with the use of Au-Ge Schottky barriers in the same
row of a similar vacancy-impurity complexes. The results obtained by ACAR spectroscopy suggest
the full-vacancy configuration of DV pair with relaxation of atoms inward towards the vacancy.
Carrier Recombination Activities and Structural Properties of Small-Angle Boundaries in Multicrystalline Silicon
Authors: Chen J. , Sekiguchi Takashi , Ito S. , Yang De Ren
Published: March 2009

The carrier recombination activities of small angle (SA) grain boundaries (GBs) in
multicrystalline Si (mc-Si) were systematically investigated by electron-beam-induced current
(EBIC). At 300 K, general SA-GBs with tilt angle from 0° to 10° showed weak EBIC contrast (0-
10%) with the maximum appeared at 2°. At low temperature (100 K), all the SA-GBs showed
strong EBIC contrast despite the tilt angle. Possible explanations for the variation of the EBIC
contrast were discussed in terms of boundary dislocations.
I: Ultra-Shallow Junction Cleaning: Metrology for Evaluating Dopant Loss and Substrate Erosion
Authors: Ameen Mike S. , Srivastava Aseem K. , Berry Ivan L.
Published: March 2009

We have investigated the use of Rs and SIMS
measurements to quantify substrate erosion
due to plasma ashing and subsequent wet
cleaning in the creation of ultra-shallow
junctions. The near-surface proximity of the
implants makes them highly sensitive to
various plasma and wet chemical processes.
We also observed a dependency on the
implant species, dose and energy that can be
correlated to substrate damage incurred during
implant.
Adhesion and Removal of Silica and Ceria Particles on the Wafer Surfaces in STI and Poly Si CMP
Authors: Hong Yi Koan , Kang Young Jae , Park Jin Goo , Han Sang Yeob , Yun Seong Kyu , Yoon Bo Un , Hong Chang Ki
Published: March 2009

The purpose of this study is to investigate the effects of slurry pH on the adhesion and removal of
silica and ceria abrasive particles on the poly Si, TEOS, SiN and SAC (self aligned memory cell
contact) and STI (shallow trench isolation) patterned wafer surfaces. The adhesion force of silica and
ceria particles were theoretically and experimentally investigated in STI and poly Si CMP process. A
stronger adhesion force was observed for silica particles on the poly Si wafer in acidic rather than in
alkaline solutions. The adhesion force of ceria particle was lower than that of silica in investigated pH
ranges. STI patterned wafer showed lower adhesion force than SAC patterned wafer. Lower adhesion
force between particles and surface resulted in a lower level of particle contamination.
Wet Process Developments for Electrical Properties Improvement Of 3D MIM Capacitors
Authors: Richard Claire Therese , Benoit D. , Cremer S. , Dubost L. , Iteprat B. , Vincent M. , De Bock E. , Perrot C. , Rossato C. , Proust M. , Guillaumet S.
Published: March 2009

3D architecture is an alternative way to high-k dielectric to increase the capacitance of MIM
structure. However, the top of this kind of structure is very sensitive to defectivity and then requires
a special wet treatment. In this paper, we present the process flow for a 3D MIM integration in a
CMOS copper back-end and a two steps wet process which provides very good electrical
performances, i.e. leakage current lower than 10-9A.cm-2 at 5V / 125°C and breakdown voltage
higher than 20V. At first, a SC1 step is done for electrode isolation improvement by material
etching with good selectivity towards dielectric: that’s the electrode recess. In the second time, a HF
step is done for copper oxide dilution and residues removal from the top of the 3D structure.
Synthesis and Characterization of NiFe2O4 Nanoparticles Synthesized by Levitational Gas Condensation (LGC)
Authors: Uhm Young Rang , Han Byung Sun , Lee H. M. , Rhee Chang Kyu
Published: March 2009

NiFe2O4 nano particles were synthesized by a simple levitational gas condensation (LGC) using Ni and Fe metal powder as starting materials. The TEM image reveals spherical particles with the range of the particle size from 8 to 22 nm. The Mössbauer spectrum revealed the presence of superparamagnetic phase with abnormal ionic states of Fe2+ and Fe3+
Comparative Studies of Cellular Permeable Solids as Catalyst Supports
Authors: Smorygo Oleg , Leonov A. , Ismagilov Z.R. , Rhee Chang Kyu
Published: March 2009

Metallic and ceramic foam catalyst supports and catalysts were manufactured. Comparative
studies of the foam-structure catalyst supports and straight-channel catalysts supports were performed.
Affect of the catalyst support pore structure upon the catalyst operational performance was
analyzed.
Fabrication of Oriented TiO2-Based Nanotube Array Thin Films
Authors: Guo Yu Peng , Lee Nam Hee , Oh Hyo Jin , Yoon Cho Rong , Rhee Chang Kyu , Lee Kyung Sub , Kim Sun Jae
Published: March 2009

In this study, we have successfully developed the technology to grow the nanotube
array thin films from dip-coated titania using hydrothermal method. The nanotube
array thin film strongly adhered onto the substrate, was formed in short time reaction
at 140°C. Even a self-supporting films, consisted of vertically aligned nanotube in
large part, were formed after long time reactions at 140°C with 10 μm in thickness.
The most probable formation mechanism of TiO2-based nanotube array thin films is
discussed.
Preparation and Characterization of AuNP/Al2O3 with Bimodal Nanoporous Structure
Authors: Kim Young Hun , Joo Ji Bong , Kim Woo Young , Lee Jeong Jin , Yi Jong Heop
Published: March 2009

AuNP (gold nanoparticle) supported by oxide shows a high reactivity for a PROX (preferential
oxiation) reaction at low temperature. Au catalysts were usually prepared by conventional methods
such as precipitation, impregnation and vapor phase grafting. In this study, we developed a novel
method for the preparation of AuNPs supported on a bimodal nanoporous alumina. The AuNPs were
prepared in a toluene phase by the modified Brust method. The metal particle size was able to be
controlled from 2 to 50 nm via the control of the surfactant concentrations. The resulting materials
were characterized by BET, FE-SEM, TEM, and XRD analyses. After calcinations at 700oC,
AuNP/Al2O3 catalyst revealed a bimodal nanoporous structure, with the pore sizes of 3.5 and 7 nm,
and demonstrated both a high surface area (350 m2/g) and pore volume (0.9 cm3/g).
Nano-Sized Yttria Dispersed Ferritic Stainless Steels for SOFC Interconnect Applications
Authors: Ahn Jung Ho , Kim H.J. , Oh Ik Hyun , Park B. H. , Jang S. H.
Published: March 2009

In the present work, we have developed two ferritic stainless steels, Fe + 20%Cr +
0.8%Mn + 0.2%Ti + 0.5%Y2O3 and Fe + 17%Cr + 0.1%C + 1%Si + 1%Mn + 0.5%Y2O3 for oxide
fuel cell (SOFC) interconnects. Nano-sized Y2O3 particles were dispersed in the metallic matrix by
high-energy ball-milling. The alloys exhibited excellent electrical conductivity and thermal
expansion coefficient suitable for SOFC applications. The finely dispersed nano-sized yttria is
thought to be attributed to high conductivity.
Preparation and Characterization of Electrospun Carbon Nanofibers with Na2CO3/H3PO4 Activation
Authors: Im Ji Sun , Park Soo Jin , Lee Young Seak
Published: March 2009

In this work, carbon nanofibers(CNFs) were prepared by using electrospinning method.
Phosphoric acid and sodium carbonate activation of CNFs were conducted to increase surface area
and pore volume. Pore structures of activated CNFs were developed with increasing surface area
and pore volume through activation. Specific surface area increased about 60 times and total pore
volume developed around 120 times. Activated CNFs have different pore distribution with different
chemical agent.
Synthesis of Cu(In0.75Al0.25)Se2 Thin Films from Binary Selenides Powder Compacted Targets by Sputtering and Selenization
Authors: Munir Badrul , Wibowo Rachmat Adhi , Kim Kyoo Ho
Published: March 2009

Cu(In0.75Al0.25)Se2 thin films were prepared using both one-step sputtering and
two-stage process involving sputtering and selenization. Structure and properties of the films
were analyzed and compared between the methods. All films had good adhesion to the
substrate and showed strong (112), (220)/(204) peaks while minor secondary phase CuxSe
was observed in the films from selenization. This paper compares the visibility of one step
sputtering process and selenization of sputtered binary selenides layers to produce
Cu(InAl)Se2 thin films (CIAS) for solar cell absorber applications. One step sputtering
deposition from binary selenides powder compacted targets can produces CIAS films with
better structural and optical properties compared to films produced by selenization of
sputtered precursors.
RF Plasma Synthesis of Boron Carbide Nanoparticles
Authors: Du S.W. , Tok Alfred Ling Yoong , Boey F.Y.C.
Published: March 2009

Boron carbide is one of the hardest materials known. The research on the synthesis of
nano-sized boron carbide is of great importance. RF plasma synthesis of B4C nanoparticle
was carried out by powder feeder using micro-sized commercial boron carbide
powder as the stating material. Different plasma energy and powder feeder probe position
was used to find out the optimum condition to achieve nanoparticles. Powders were
collected from Chamber 1, 2 and 3. fine particles can be achieved, but the decomposition
and oxidation of B4C powder during the high temperature plasma spray was detected.
Boron oxide was found in the sprayed powder, and the powder was purified by washing
and heat treatment. XRD, SEM and TEM was used to for characterization of the
particles.
Self Healing of Epoxy Composite for Aircraft's Structural Applications
Authors: Tan Willy C.K. , Kiew J.C. , Siow K.Y. , Sim Z.R. , Poh H.S. , Taufiq M.D.
Published: March 2009

When one cut himself, it's amazing to watch how quickly the body acts to mend the wound. Immediately, the body works to pull the skin around the cut back together. The concept of repair by bleeding of enclosed functional agents serves as the biomimetric inspiration of synthetic self repair systems. Such synthetic self repair systems are based on advancement in polymeric materials; the process of human thrombosis is the inspiration for the application of self healing fibres within the composite materials. Preliminary results based on flexural 3 point bend test on prepared samples have shown the healed hollow fibre laminate has a healed strength increase of 47.6% compared to the damaged baseline laminate. These results gave us confidence that there is a great potential to adopt such self healing mechanism on actual composite parts like in aircraft’s composite structures.
Growth of PLZT Thick Films by Polymer Modified Sol-Gel Processing for Optical Shutting
Authors: Du Z.H. , Zhang T.S. , Shang H.M. , Chen X.L. , Ma Jan
Published: March 2009

PLZT9/65/35 thick films were prepared from the solution containing PVP360 (polyvinylpyrrolidone, with average molecular weight of 360000). With the solutions, the critical thickness of a single PLZT layer could increase to ~624nm compared with 77nm-thick films prepared without PVP360. Furthermore, by adding 20~35% excess of Pb to the precursor solutions, the nano-porous rosette-like structures and a small amount of pyrochlore remnant, which were found very common in the PVP-modified films, could be eliminated. 35% Pb excess was also found to initiate liquid-phase sintering, leading to dense and crack-free films. The effect of Pb excess on the rosette removal and densification behavior of the films was discussed. Moreover, the optical and electrical properties of the PLZT films with 35% Pb excess were also studied.
Computer Simulation of the Interaction of Junction Disclinations in Nanomaterials with Grain Boundary Vacancies
Authors: Nazarov Ayrat A. , Murzaev Ramil’ T.
Published: March 2009

Junction disclinations are important elements of the structure of nanostructured metals
produced by severe plastic deformation (SPD). Effect of these defects on the formation energy of
vacancies in grain boundaries (GBs) is studied by means of atomistic computer simulations.
Estimates based on the calculations of vacancy formation energies suggest that at least two orders of
magnitude increase of the GB diffusion coefficient can be expected due to junction disclinations in
nanostructured metals.
On the Formation of High Damping State in Fe-Al and Fe-Cr Alloys
Authors: Chudakov I.B. , Polyakova Nataly A. , Mackushev S.Yu. , Udovenko V.A.
Published: March 2009

High damping Fe - Cr and Fe - Al alloys have been studied in two different states: in the
high damping state and in the suppressed damping capacity state. It has been shown that magnetic
domain structures of Fe - Cr and Fe - Al alloys are fundamentally different in the high damping state
and in the state with the suppressed damping. Magnetic domain structure corresponding to the high
damping state can be characterized by an enhanced volume fraction of the easy movable 90o-domain
walls, but the state with the suppressed damping capacity can be characterized by the enhanced
volume fraction of the 180o-domain boundaries.
Effect of Cold Rolling on the Damping of As Cast Cu-Al-Mn Shape Memory Alloys
Authors: Mielczarek Agnieszka , Wöckel Yvonne , Riehemann Werner
Published: March 2009

The ductility of Cu – Al – Mn shape memory alloys at room temperature depends on the
aluminium content. High aluminium contents make Cu – Al – Mn very brittle and unsuitable for
plastic shaping. Two Cu – Al – Mn shape memory alloys were investigated. The ductile alloy
CuAl7.8Mn9.5 (all contents in wt. %) could be easily cold rolled by 86 %. The alloy CuAl12Mn4.3
could be cold rolled by only 12 - 14 %. The amplitude dependence of damping of austenitic
specimens increased with increasing degree of cold work, whereas the damping of martensiticaustenitic
specimens decreased. These observations can be explained by the creation of stress
induced martensite and therefore by new moveable interfaces like phase- and twin boundaries,
which contribute to damping. Plastic deformation increases the dislocation density, too. Both the
increase of dislocation density and the increase of martensite content can lead to a decrease of
damping mainly for high deformation degrees. Same shape memory alloys have shown negligible
hardness increase during cold rolling, too. This behaviour, untypical for metals, can be explained by
the generation of new martensite and by the fact that the hardness of martensite is smaller than the
hardness of austenite. Some aging effects of the specimen after cold rolling, which lead to decrease
of damping, were detected. This can be explained by pinning of moveable interfaces by point
defects and/or retransformation of martensite into austenite.
Damping in AZ31 ECAP-Processed Alloy
Authors: Ivleva Tatiana V. , Göken Jürgen , Golovin Igor S. , Zuberova Zuzana , Maikranz-Valentin Manuel , Steinhoff Kurt
Published: March 2009

Study of anelasticity in AZ31 magnesium-based alloy in initial (hot-rolled at 370 оС)
condition and after one and four passes of equal channel angular pressing is carried out. An internal
friction peak was found at 170 °C at a frequency f of about 1 Hz. Two possible mechanisms of this
peak are discussed: it is suggested that the peak origin is the grain boundary relaxation.
Study of PPV Polymer Layers on Si Substrates by Mechanical Spectroscopy
Authors: Strahl A. , Schrader Sigurd , Katholy S. , Grimm B. , Neuhäuser Hartmut
Published: March 2009

Thin layers of the OLED related polyphenylene-vinylene (PPV) deposited by a precursor
on micro-fabricated Si cantilevers were studied by applying the vibrating-reed technique during
repeated temperature cycling between 100 and 520 K. By means of the Langmuir-Blodgett method
for film production, the dependence of damping and elastic modulus on well defined values of film
thickness (16 to 69 nm) was determined. Simultaneous measurements of these quantities showed
four damping peaks during heating around 130 K (called γ), 250 K (β), 350 K (β’), and 400 K
(called C). Three of them (γ, β’, C) disappeared after heating to the highest temperature (520 K)
indicating their presence in the precursor only. The activation parameters of the relaxation peaks (γ,
β, β’) were estimated and assigned to specific atomic movements in the molecule. Peak C occurs
during the conversion process of precursor to polymer. Earlier results are essentially substantiated,
indicating only slight differences to those for layers produced previously by spin coating. The observed
thickness dependence of damping for the γ and β peaks suggests a weaker contribution of
molecules in the surface region than of those in the bulk, while the β’ peak is supposed to result
from molecules in the interface region between layer and substrate.
High-Temperature Mechanical Relaxation due to Dislocation Motion inside Dislocation Networks
Authors: Rivière Andre , Gerland Michel , Pelosin Veronique
Published: March 2009

Internal friction peaks observed in single or polycrystals are clearly due to a dislocation
relaxation mechanism. Because a sample observed by transmission electron microscopy (TEM)
often exhibits in the same time various dislocation microstructures (isolated dislocations,
dislocation walls, etc.) it is very difficult to connect the observed relaxation peak with a particular
dislocation microstructure. Using isothermal mechanical spectroscopy (IMS), it is easier to
compare, for instance, the evolution of a relaxation peak with measurement temperature to the
microstructural evolution observed by in-situ TEM at the same temperatures. IMS was used to
study a relaxation peak in a 5N aluminium single crystal firstly 1% cold worked and then annealed
at various temperatures. TEM experiments performed in the same material at various temperatures
equal to the temperatures used for the damping experiments made possible to link this internal
friction peak with a relaxation effect occurring inside dislocation walls. In two other experiments in
a 4N aluminium polycrystal and in a metal matrix composite with SiC whiskers, it is shown that the
observed relaxation peaks are connected to the motion of dislocations inside polygonization
boundaries in the first case and in dislocation pile-ups around each whisker in the second one.
Theoretical models proposed to explain such relaxation peaks due to a dislocation motion inside a
dislocation wall or network are discussed.
Mechanical Spectroscopy of Oil Films on Metallic and Neutral Substrates
Authors: Magalas Leszek B.
Published: March 2009

Characteristic low-temperature mechanical loss peaks are reported in cold-rolled steel
sheets. Similar mechanical loss peaks are observed in both metallic and paper substrates covered
with thin oil films. The surface induced origin of these peaks is elucidated through direct
comparison of mechanical loss peaks observed in the as-received, cold-rolled samples with loss
peaks observed in metallic and paper substrates covered with thin films of the arachis oils. In all of
these instances, similar low-temperature mechanical loss peaks are observed in the temperature
range from 180 K up to 300 K in both low-frequency resonant and low-frequency sub-resonant
mechanical spectrometers. It is concluded that low-temperature mechanical loss peaks are generated
by surface induced effects that arise from the oil film itself.
Structure and Anelasticity of Fe-Ge Alloys
Authors: Golovin Igor S. , Ivleva Tatiana V. , Jäger S. , Jencus P. , Neuhäuser Hartmut , Redfern S.A.T. , Siemers C.
Published: March 2009

Several ternary Fe – Ge - C alloys with Ge contents ranging between 3 and 27 at. % have
been studied. The structure, anelastic, thermodynamic and kinetic phenomena in Fe - 3, - 12, -
19/21 and – 27 Ge have been examined by X-ray diffraction (XRD), heat flow (DSC), vibrating
sample magnetometry (VSM), optical-light and scanning electron microscopy, and internal friction
(IF) methods. The Fe - 3Ge and Fe - 12Ge alloys form b.c.c. solid solutions. A Snoek-type internal
friction (P1) peak is recorded in the Fe - 3Ge alloy with parameters similar to those for α-Fe:
Н = 0.86 eV, Δ = 0.015, β = 0.72 and τ0 = 2 × 10-15 s, showing that Ge atoms have little influence on
the diffusivity of carbon in iron. The Fe - 12Ge alloy, with a Curie point around 1008 K, has several
IF peaks: a broad Snoek-type (P1 and P2), the P3 peak caused by structural changes in as quenched
specimens during annealing, and a P4 (Zener) peak at higher temperature (Tm ≈ 773 K at f = 2 Hz,
β ≈ 0.7). The Fe - 21Ge alloy has bcc or bcc plus hexagonal structure depending on heat treatment.
The structure of the Fe3Ge-type alloy (Fe - 27Ge) consists mainly of hexagonal phases, i.e. hexagonal
ε (D019), β (B81), and cubic ε′ (L12), and exhibits corresponding magnetic ordering transitions
below 873 K which are not well-reflected in the common Fe - Ge phase diagrams. In particular a
high stability of the hexagonal ε phase at room temperature is noted. A broad internal friction relaxation
peak with Δ = 0.0036, H ≈ 1.8 eV and τ
0 = 2 ⋅ 10-17 s is found in Fe – 27 Ge and is classified
as a double Zener peak in the ε and β two-phase mixture.
Snoek-Type and Zener Relaxation in Fe-Si-Al Alloys
Authors: Golovin Igor S. , Jäger S. , Semin V.A. , Serzhantova G.V. , Sinning H.R. , Sokolova Olga A. , Stein F. , Golovin S.A.
Published: March 2009

Carbon-containing Fe - Si and Fe - Si - Al alloys were studied with respect to the carbonrelated
Snoek-type and Zener relaxation using different mechanical spectroscopy techniques. In all
alloys the temperature-dependent profile of the Snoek peak, relative to that in pure iron, is modified
on its high-temperature side by the substitutional atoms. At least two components, an Fe - C - Fe
(which correspond to C atom jumps (diffusion) in areas where it is surrounded by Fe atoms only)
and Fe - C - Me peaks, where Me = Si, Al, can be distinguished in the Snoek-peak profile. In both
binary Fe - Al and Fe - Si and ternary Fe - Si - Al alloys, a higher annealing temperature prior to
quenching leads to an increase in the Fe - C - Fe and a decrease in the Fe - C - Me component of
the Snoek peak. Heating to 1173K and above often lowers the peak height due to thermal vacancies.
Low-temperature (<670K) ageing of quenched Fe - Si - Al and Fe – Si specimens reduces both the
Fe – C - Fe and Fe – C – Al / Si peaks. Ageing at T > 670 K changes the temperature- as well as the
amplitude-dependent parts of internal friction due to a redistribution of carbon between solid
solution and dislocations. Both the Snoek-type peak height and the dislocation mobility – as can be
concluded from the slope of the amplitude-dependent internal friction – increase, and a new peak
appears at temperatures higher than that of the Snoek peak, which probably is a Snoek-Köster peak
resulting from the motion of weakly pinned dislocations. A Zener peak appears if the concentration
of substitutional atoms is > 6 at. %. The Zener peak relaxation strength is much lower in ternary
alloys than in the binary ones probably due to mutual compensation of elastic distortions in
presence of Al and Si atoms which are bigger and smaller, respectively, than Fe atoms.
Nonlinear Correlated Interaction of Mesodefects and Transition to Macrofracturing
Authors: Leksowskij Albert , Baskin B.L. , Tishkin A.P. , Abdumanonov A.
Published: March 2009

The following experimental data are presented and discussed: a) the explosion-like
nucleation of micro- (meso) cracks; b) the dependence of the scale of local “microcatastrophe” on
the relation between the released strain energy and the dissipative properties of the nearest
environment; c) the determinative influence of the dissipative properties on the rate of redistribution
of local stresses. The presented data evidence that every event of defect nucleation that takes place
at either micro- or mesoscale level in the heterogeneous solid examines the energy absorbtion
properties of the whole system. Future localization of the macroscopical failure is of “accidental
type”, that is results from random, active formation of the ensemble of micro- and mesocracks in
different localities as a consequence of the decrease of the dissipative capability of surrounding
volume.
Analysis of Possibilities of Fisher’s Model Development
Authors: Popov Vladimir V.
Published: March 2009

The possibilities of Fisher’s model development and generalization are considered, as this model in its classical form contradicts some experimental results. Particularly, it does not explain such a phenomenon, observed in Mössbauer studies, as the transfer of grain-boundary diffusing atoms into near-boundary crystallite areas at temperatures when the volume diffusion is admittedly frozen. Different models explaining this phenomenon are briefly reviewed, the greatest attention being paid to a model accounting for the presence of equilibrium-composition near-boundary layers. It is demonstrated that based on the results of grain boundaries investigations one can conclude that at relatively low temperatures (< 0.35 – 0.40 Tm) the diffusant pumping from a grain boundary proceeds much faster than volume diffusion, and possible reasons for that are considered.
Effect of Dissolution on the Ni3Sn4 Growth Kinetics at the Interface of Ni and Liquid Sn-Base Solders
Authors: Dybkov Vasil I.
Published: March 2009

The Ni3Sn4 intermetallic layer occurs at the interface of nickel and the saturated or undersaturated Sn-base solder melt at 250-450 °C and dipping times of 300 to 2400 s. Mathematical equations are proposed to evaluate the thickness of the Ni3Sn4 layer formed under conditions of simultaneous dissolution in the undersaturated solder melt.
Vaporization and Thermochemical Study of SrCeO3(s) and SrCe0.95Yb0.05O3(s) by Knudsen Effusion Mass Spectrometry
Authors: Miller Miroslav , Matraszek Aleksandra
Published: March 2009

The vaporization of samples in the SrO-CeO2 system was investigated by the use of
Knudsen effusion mass spectrometry in the temperature range of 1494 K – 1988 K. Partial pressures
of the gaseous species O2, CeO2, Sr, and SrO were determined over the samples investigated. The
partial pressures of the species were used for the evaluation of thermodynamic activities of CeO2
and SrO in the samples at 1800 K. The enthalpy of formation of SrCeO3(s) was obtained as
fH°(298 K) = -1644 ± 21 kJ mol-1. The Gibbs energy of formation of SrCeO3(s) from SrO(s) and
CeO2(s) resulted as fG°(1800 K) = -12.5 ± 2.8 kJ mol-1 for the phase field {SrCeO3 + ss of SrO in
CeO2} and fG°(1800 K) = -13.7 ± 2.1 kJ mol-1 for the phase field {SrCeO3 + SrO}. The influence
of the Yb concentration in the perovskite phase SrCe0.95Yb0.05O3 on the CeO2(s) activity was studied
as well. The thermodynamic properties obtained in the present study are discussed on the basis of
the data available in literature.
Calculation of Some Thermodynamic Parameters of Non-Ideal Solutions
Authors: Asadov MirSalim M. , Akhmedly K.M.
Published: March 2009

A computational method has been proposed for calculating the correct interaction parameters
from experimental phase diagrams, despite reports that this problem was believed to be a
"thermodynamically incorrect” one. It has been shown that the presumed difficulties are not of
fundamental importance. An original computer program has been applied to two well-known
systems Bi – Sb (1) and Bi2Te3 – Sb2Te3 (2), and a good agreement between calculated and
observed values has been achieved. The values of interaction parameters s= 7.1 ± 0.4, l= 1.56 ±
0.09 kJ mol-1 for (1) and s = 5.9 ± 2.5, l = 3.9 ± 2.5 kJ mol-1 for (2) have been found. The results
have been analyzed and their statistical reliability has been established. In addition, the possibilities
of calculating the liquidus curve from only the solidus experimental data the solidus from the
liquidus experimental data have been demonstrated. It has been found that the prediction of liquidus
from solidus is much more successful than predicting the solidus from the liquidus.
The results allow one to determine with reliance that the backward problem of modeling regular
solutions for finding thermodynamic interaction parameters can be solved correctly. The calculated
parameters can be used for both the computational restoration of missing pieces of the experimental
phase equilibrium diagrams of binary and multinary systems and for the recognition of the physical
nature of regular solutions.
The Development of “Macroscopic Composition Gradient Method” and its Application to the Precipitate-Nucleation Near the Edge of Miscibility Gap
Authors: Miyazaki Toru
Published: March 2009

A new characterization method, "Macroscopic Composition Gradient (MCG) Method" is
proposed to investigate the phase transformations near the phase boundaries, such as the solubility
limit, order/disorder line and so on. Since the macroscopic composition gradient in the alloy is
prepared so as to step over the phase boundary, the morphological transition of critical phenomena
at the phase boundary can be observed by means of analytical transmission electron microscopy.
By utilizing this method, the critical minimum size of stable precipitate in the vicinity of edge of
miscibility gap is experimentally determined for the Ni3Si in Ni-Si, Ni3Al in Ni-Al, Cu4Ti in Cu-Ti
and Co in Cu-Co binary alloy systems. The results are as follows: The critical nucleus size shows a
steep increase up to several tens of nm in a very narrow composition range less than 0.3at% from
the phase boundary. The Gibbs-Thomson relation and the conventional nucleation theory
statistically rationalize such the composition dependence of nucleus size change. However, the
nucleus formation is kinetically never rationalized by the conventional nucleation theories. The
phase decomposition of supersaturated solid solution progresses by a mechanism of spinodal phase
decomposition, even in the composition range near the solubility limit, i.e. a so-called Nucleation-
Growth region. Such the phase decomposition behavior is never rationalized by the Boltzmann-
Gibbs free energy, which is based on the extensive entropy. The experimental facts obtained here
are explained by Tsallis's non-extensive entropy.
It should be noted that the present experiments can systematically be conducted in the
composition range very near the solubility limit where they has hardly been examined in the past.
The MCG method proposed here is considered to open a new way to investigate the microstructure
evaluation, particularly for the critical phenomena near the phase boundary.
Computer Simulation of Polymer Chains in Confinement
Authors: Sikorski Andrzej
Published: March 2009

Properties of macromolecules confined in a narrow slit, pore or capillary are important due to of their practical importance. Theoretical treatment of such systems is also interesting because the introduction of confinement has an impact on most properties of polymer chains and it gained a longstanding attention. In order to determine the properties of such systems coarse-grained models of confined polymers were designed where macromolecules were represented by united atoms. Lattice approximation was also often introduced. Different macromolecular architectures were studied: linear, cyclic and star-branched chains. Computer simulation techniques (the variants of the Monet Carlo method like the Metropolis algorithm and the Replica Exchange method as well as Molecular Dynamics and Brownian Dynamics methods) applied for studies of such models were reviewed and evaluated. The structure of the polymer film and the dynamic properties were mainly presented and discussed. The influence of the width of the slit, the temperature and the force field on the dimension and the structure of chains were studied. It was shown that a moderate confinement stabilizes folded chains while a strong confinement does not.
Shock Loading of Bone-Inspired Metallic Nanocomposites
Authors: Sen Dipanjan , Buehler Markus J.
Published: March 2009

Nanostructured composites inspired by structural biomaterials such as bone and nacre
form intriguing design templates for biomimetic materials. Here we use large scale molecular
dynamics to study the shock response of nanocomposites with similar nanoscopic structural features
as bone, to determine whether bioinspired nanostructures provide an improved shock mitigating
performance. The utilization of these nanostructures is motivated by the toughness of bone under
tensile load, which is far greater than its constituent phases and greater than most synthetic
materials. To facilitate the computational experiments, we develop a modified version of an
Embedded Atom Method (EAM) alloy multi-body interatomic potential to model the mechanical
and physical properties of dissimilar phases of the biomimetic bone nanostructure. We find that the
geometric arrangement and the specific length scales of design elements at nanoscale does not have
a significant effect on shock dissipation, in contrast to the case of tensile loading where the
nanostructural length scales strongly influence the mechanical properties. We find that interfacial
sliding between the composite’s constituents is a major source of plasticity under shock loading.
Based on this finding, we conclude that controlling the interfacial strength can be used to design a
material with larger shock absorption. These observations provide valuable insight towards
improving the design of nanostructures in shock-absorbing applications, and suggest that by tuning
the interfacial properties in the nanocomposite may provide a path to design materials with
enhanced shock absorbing capability.