bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer Modelling of Oxygen Mobility at Ceria Surfaces and the Construction of Ceria Nanotube Models
Authors: Martin P. , Parker S. C. , Sayle D.C. , Watson G.W.
Published: March 2009

The aim of this paper is to describe the recent progress in using atomistic simulation techniques to develop simulation models of ceria nanotubes and to model oxygen ion transport at ceria surfaces. The basis of these atomistic techniques is to use the Born Model of Solids where parameterized analytical equations are employed to describe the interactions between atoms. Once these interatomic forces are specified energy minimization and molecular dynamics techniques can be applied to the models.
Extraction of Diffusion Correlation Information from Tracer, Interdiffusion and Ionic Conductivity Data
Authors: Belova Irina V. , Murch Graeme E.
Published: March 2009

In this paper, the current understanding about the relationships between
tracer diffusion coefficients, interdiffusion coefficients and d.c. ionic conductivities in
metallic alloy and ionic systems is reviewed with emphasis on recent progress. Quasione
component systems are analyzed in terms of the Haven Ratio (and tracer and
collective correlation factors). Two and three component alloy systems are analyzed
in terms of the Darken-Manning equation and vacancy-wind factors (and tracer and
collective correlation factors). Ionic systems with two mobile components are
analyzed in terms of a corrected Nernst-Planck Equation.
Electric-Field-Enhanced Thermal Emission from Osmium-Related Deep Level in n-GaAs
Authors: Zafar Iqbal M. , Majid A. , Dadgar Armin , Bimberg D.
Published: March 2009

Deep-level defects related with 5d transition metal, osmium (Os) have been studied in ntype
GaAs. Os has been incorporated in epitaxial n-GaAs layers in situ, during growth by lowpressure
metal-organic chemical vapour phase epitaxy (MOVPE) technique. Mesa p+nn+ junction
diodes are fabricated for investigations by deep level transient spectroscopy (DLTS). Two deeplevel
peaks, observed in majority carrier (electron) emission spectra, Os1 and Os2, show a
significant shift in peak positions to lower temperatures with the applied junction reverse bias,
demonstrating enhancement of the thermal emission rate by the junction electric field. Doublecorrelation
DLTS (DDLTS) measurements have been employed for accurate quantitative
investigations of the observed field dependence. However, in view of the relatively small
concentration of the deep level Os1, this technique is found to yield reliable data only for the deep
level corresponding to the dominant peak, Os2. Detailed data have been obtained on the field effect
for Os2, extending over junction electric field values 3 x 106 V/m - 1.2 x 107 V/m. The measured
emission rate signatures show a reduction of the thermal activation energy from 0.48 eV to 0.21 eV
for Os2 over this electric field range. Analysis of the data in terms of the recent theoretical work on
field dependence indicates that Os2 is associated with a substitutional Os donor.
Influence of Elasticity of Dislocations on Thermal Motion of Trapped Liquid Pb Inclusions in Al
Authors: Prokofjev S.I. , Johnson Erik , Zhilin V.M. , Dahmen U.
Published: March 2009

Thermal motion of nanoscale liquid Pb inclusions attached to fixed dislocations in thin Al foils is investigated using in-situ TEM. In contrast with 3D random motion of free inclusions, the attached inclusions demonstrate oscillations in the close proximity of the dislocations. This is due to the elasticity of the dislocations. It is found that inclusions captured by one dislocation repulse at small separations, and attract at large ones and this is also caused by the dislocation elasticity. Such behaviour of trapped inclusions can be considered as a motion in a potential well or in coupled potential wells in the case of motion of several trapped inclusions on one dislocation. The potential of interaction of an inclusion with a dislocation and the potential of mutual interaction between inclusions are determined.
Sol-Gel Ink-Jet Printing Technique for Synthesis of Buffer Layers of Coated Conductors
Authors: Cloet V. , Cordero-Cabrera M.C. , Mouganie T. , Glowacki Bartek A. , Falter M. , Holzapfel B. , Engell J. , Bäcker M. , Van Driessche Isabel
Published: March 2009

In this present work, two buffer layers (La2Zr2O7 and CeO2) were deposited by a non-contact
computer-controlled ink-jet coating technique with sol-gel precursors on highly textured Ni-5%W
Rolling Assisted Biaxially Textured substrates (RABiTS). Lanthanum acetate and cerium
acetylacetonate were used as precursors for the LZO and CeO2 sol respectively. After a high
temperature heat treatment (heating at 900°C for LZO and at 1100°C for CeO2) under reducing
atmosphere, epitaxial textured buffer layers were obtained. XRD and pole figures were used to
analyse the texture of the films, the microstructure was analysed by SEM.
Fabrication of Bi2Sr2Can-1CunOy / Al2O3-Particles on MgO Films by rf Magnetron Sputtering Method
Authors: Yamane T. , Kishida Satoru , Tanaka H. , Yoshikawa Hideki , Imao Hiroya
Published: March 2009

We deposited Bi2Sr2Ca1Cu2Oy (Bi-2212) superconducting thin films on MgO
substrates with or without Al2O3 particles by the rf magnetron sputtering method. From
the results, we found that optimum target-substrate distance, rf powers and substrate
temperature for obtaining the Bi-2212 films on the MgO substrates were 5mm, 150W
and 830°C, respectively. The Bi-2212 films were Bi-2212 single-phase and had the Tc
of about 54K . The particle size and the distribution density of Al2O3 were controlled by
annealing temperature. The Bi-2212/Al2O3/MgO film showed Bi-2212 single-phase,
whereas did not show zero-resistance.
Progress in the Continuous Depostition of YBCO Coated Conductors by Thermal Co-Evaporation
Authors: Gilioli E. , Gauzzi Andrea , Bindi Massimiliano , Rampino S. , Pattini F. , Bissoli F. , Ginocchio Stefano , Baldini M. , Zannella Sergio
Published: March 2009

We report on recent progress towards the continuous deposition of YBCO Coated
Conductors (CC) by thermal co-evaporation. This is an attractive vacuum technique thanks to the
simplicity, low cost and intrinsic uniformity over large areas. Recently, we published the in situ
preparation route of 1 μm thick superconducting YBCO films deposited onto CeO2 buffered Ni
biaxially textured tapes using a reel-to-reel system; end-to-end critical current densities Jc's at 77 K
and self-field, measured by transport measurements are in the 1-2 MA/cm2 range for 1 m. long
samples, with zero-resistance Tc= 87 K and transition widths DTc<3 K.
In spite of the very good CC’s performances reported by a number of laboratories all over the
world, several steps must be optimized in order to limit the CC production costs, in particular
concerning the complexity of the CC architecture and the choice and optimization of the YBCO
deposition technique.
We specifically address the following critical points regarding: 1) the in situ oxidation of the YBCO
layer using a novel supersonic nozzle, 2) the deposition by thermal or e-beam evaporation of thick
crack-free CeO2 buffer layers and 3) the scaling-up of the deposition process using a new multichamber
system.
Recent Progress in Rapid-Single-Flux-Quantum Circuits
Authors: Fujimaki Akira , Yamada Takahiro , Tanaka Masamitsu , Akaike Hiroyuki , Yoshikawa Nobuyuki , Terai Hirotaka , Yorozu Shinichi
Published: March 2009

We describe recent topics of rapid-single-flux-quantum (RSFQ) circuits. Much higher
integration and higher-speed operation are required for commercializing the RSFQ circuits in any
application. To satisfy this requirement, we measure several kinds of time fluctuations that possibly
limit the integration level and operating speed, and introduce the flexible passive transmission line
technology including a multicasting transmitter. In addition, we describe our ongoing applications. A
multiple-detectors-system is expected to open a new application field of an RSFQ-based
analog-to-digital converter and a digital signal processor. As for a microprocessor application,
increased number of arithmetic logic units may be effective for enhancing the computing
performances.
Concepts for HTS and MgB2 in Transformers
Authors: Tixador Pascal
Published: March 2009

After the emergence of AC NbTi strands, superconducting transformers were successfully
built. But the very high cost of 4 K cryogenics made these transformers economically not attractive.
The high Tc superconductors (HTS), operating at much higher temperatures, change these
conclusions with low cost HTS conductors. The high cost of PIT tapes and the relatively large AC
losses remain issues. The second generation HTS wires, the REBCO coated conductors, are under
development and achieved substantial progress recently. They operate at higher temperatures and
intrinsically show lower AC losses especially for transformers. MgB2 is the third option. The
magnetic flux density conditions make possible the operation at 27 K and they show low costs.
This paper provides a preliminary design for an on-board 40 MVA transformer using YBCO coated
conductors and MgB2 wires. Both superconducting transformers show similar volume and weight.
The power density per unit mass and volume is improved by a factor about two, cryogenic
included, compared to resistive systems. This makes them very attractive for on-board mobile
systems. The economical point of view will be discussed based on some targets price/performance
for superconductors and cryocoolers. MgB2 is penalized by its operation at lower temperature
(27 K / 77 K), which makes cryogenics very expensive. The advantage of the low cost of MgB2
compared to REBCO may be lost except with very low AC loss MgB2 tapes.
High-Pressure High-Temperature Synthesis of Nanostructural Magnesium Diboride for Electromotors and Devices Working at Liquid Hydrogen Temperatures
Authors: Prikhna Tatiana , Gawalek Wolfgang , Savchuk Yaroslav , Sergienko Nina , Moshchil Viktor , Dub Sergey N. , Sverdun Vladimir , Kovalev Leo , Penkin Vladimir , Rozenberg Oleg , Zeisberger Matthias , Wendt Michael , Fuchs Gunter , Grovenor Chris , Haigh Sarah , Melnikov Vladimir S. , Nagorny Peter
Published: March 2009

Addition of Ti and Zr to high-pressure (HP) synthesized MgB2 results in an increase of
critical current density of the material due to the absorption of impurity hydrogen coming most
likely from the materials of a high-pressure cell. The results of the studies of structure, critical
current density, trapped field and mechanical characteristics are discussed. High-pressure
synthesized MgB2 (with Ti additions) blocks were for the first time used in a SC electromotor at
20 K and demonstrated the efficiency similar to that of MT-YBCO bulk (at the same working
temperature).
Synthesis of YBa2Cu3O7-δ Using Oxalate Precursors and Sol-Gel Method
Authors: Bustamante D. Angel , Osorio A. Ana M. , De Los Santos V. Luis , Carhuancho A. Hilda , González G. J.C. , Cernicchiario Geraldo R.C. , Feijoo L. Juan Augusto
Published: March 2009

In this work we present the results about the preparation of the superconductor
YBa2Cu3O7-δ (Y123) by sol-gel method using oxalate precursors. Samples were prepared by
dissolving stoichiometric mixtures of Y(OOCCH3).4H2O, Ba(OOCCH3)2 and Cu(OOCCH3)2.H2O
acetates in aqueous solution of oxalic acid, HCOO-COOH. The particulate sols obtained (2g.) were
divided in two parts (1g. each one), from which the first one (sample A) was grinded, pellet,
calcined (860°C) and sinterised at 860°C in oxidizing atmosphere, the second part (sample B) was
grinded, pellet, calcined at 880°C and finally sinterized at 880°C in the same conditions, the XRD
revels the superconductor Y123 is formed in the first sample, but coexisting with remarkable
presence of the secondary phases: CuO, BaCu3O4, BaCO3 and BaCuO2, while in sample B the XRD
reveals the obtention of high purity monophase Y123, the ac susceptibility measurement using a
Quantum Design (SQUID) magnetometer indicates TC(onset)=92K for this sample, moreover the
Rietveld refinement was done taking the orthorhombic Pmmm Y123 spatial group as a model, this
suggest the cell´s parameters a=3.839Å, b=3.899 Å and c=11.702Å as reported in the literature.
Therefore for the preparation of Y123-superconductor using oxalate precursors, the optimus
sintering temperature is 880°C.
Change of Superconducting Parameters of Y-Ba-Cu-O Slabs and Rings due to High-Energy Ion Beams
Authors: Kirschner I. , Balogh A. , Mészáros Cs. , Laiho R. , Kovács Gy. , Leppävuori S.
Published: March 2009

Different high-Tc superconducting Y-Ba-Cu-O samples of slabs and rings have been
investigated. Using differently prepared Y1Ba2Cu3O7-d materials, significant deviations between
irradiated and unirradiated specimens have been detected in their properties. These investigations
demonstrate that unlikely prepared superconductors are differently sensitive to the external
irradiation, although they have the same composition. The irradiation applied during these
experiments consisted of high-energy Bi-ions with the flux of 5x1010 ions/cm2 and with the energy
of 720 MeV. As is experienced, a considerable variation of the magnetic moment in the extent of
19-44% and a significant increase of the critical current density up to 41% can be detected. These
originate from the change of the properties of materials due to the irradiation. For the evaluation of
the experiments a new fitting method is elaborated for the temperature dependence of the critical
current density, providing fully correct results for the whole temperature interval. The A.C.
magnetic measurements show, that the irradiation causes to reach the state of the perfect
diamagnetism at higher temperatures, than in the case of unirradiated samples. Similarly, the
irradiated specimens have much lower losses, than the unirradiated ones and even these smaller
values disappear at low temperatures.
Highly Densified MgB2 Bulks by Reactive Mg Liquid Infiltration
Authors: Giunchi Giovanni , Ripamonti Giovanni , Perini Elena , Ginocchio Stefano , Bassani Enrico , Cavallin Tommaso
Published: March 2009

The issues in the conventional sintering of the MgB2 superconductors have conducted to
the discovery of a new way to densify this material. The new process is an “in situ” method that
relies on the reactive liquid infiltration (RLI) of liquid Magnesium into Boron powders packed
preform. The RLI process allows to obtain highly dense manufacts without the use of hot pressing
apparatus and can be applied to the manufacture of large superconducting pieces. One of the
peculiarities of the MgB2 superconductivity, that withstand up to 39 K, is represented by the
relative insensitiveness of the supercurrent percolation to the orientation of the grain boundaries.
This property allows to use polycrystalline material without loosing superconducting performance,
granted that a good connectivity between the crystalline grains must be realized, as the RLI process
allows to do. The microstructure of the bulk material obtained by RLI shows a variety of
morphologies, according to the kind of the used Boron powders and to the process variables. A
detailed analysis of the microstructure of the MgB2 obtained by RLI will be presented, as well as
its analytical description and the correlation with the superconducting characteristics.
Point-Contact Spectroscopy in Doped and Irradiated MgB2
Authors: Daghero Dario , Gonelli R.S. , Calzolari A. , Ummarino G.A. , Tortello M. , Stepanov V.A. , Zhigadlo N.D. , Rogacki K. , Karpinski J. , Putti M.
Published: March 2009

We review recent results of point-contact spectroscopy (PCS) in doped (with Al, C or
Mn) and neutron-irradiated samples of the two-band superconductor MgB2. The aim of these
measurements was to clarify the role of inter- and intra-band scattering, and to test the theoretical
expectations about the effects of substitutions and disorder on two-band superconductivity. The gap
amplitudes, Δπ and Δσ, were obtained as a function of the critical temperature of the junctions (or of
the doping content) by fitting the conductance curves with the two-band BTK model. The analysis
of the resulting curves within the Eliashberg theory allowed us to extract information on the partial
DOSs, as well as on the scattering rates within and between the two bands. The results are discussed
and compared to theoretical expectations.
Fluctuating Diamagnetism in the Critical Region of the Superconducting Transition in Lead Nanoparticles
Authors: Bernardi E. , Lascialfari A. , Rigamonti A. , Romanò L. , Iannotti Vincenzo , Ausanio G. , Luponio Carlo
Published: March 2009

High resolution SQUID magnetization measurements in Lead nanoparticles are presented
and discussed in terms of the fluctuation-related diamagnetism in the critical region of the transition
to the superconducting state, where the first-order fluctuation theory breaks down. Exact
expressions of the magnetization are derived from the Ginzburg-Landau functional in zerodimensional
condition (i.e. for grain size lesser than the coherence length) and are used to achieve
insights on the properties of the critical fluctuating diamagnetism.
Growth of Phosphorous Doped n-Type Diamond and the Electrical Properties
Authors: Koizumi Satoshi
Published: March 2009

We have succeeded to grow high quality phosphorus doped n-type diamond thin films on
{111} diamond substrates. Although the ionization energy of phosphorus donor is large (0.57 eV),
the n-type conductivity is clearly observed by Hall measurements. The Hall mobility is as high as
660 cm2/V-sec at room temperature. In this paper, current status of n-type diamond research are
mentioned mainly focused on the growth of high mobility n-type diamond and its electrical
properties. High quality diamond growth has been carried out by surface pre-treatment of diamond
substrate. The Hall measurements performed in a wide temperature range gives detailed information
about the n-type conductivity nature.
Growth and Characterization of Tungsten Oxide for Applications in Nanoelectronics
Authors: Sridharan Karthikk , Roberts Kenneth P. , Mitra Saibal
Published: March 2009

Tungsten oxide nanorods were prepared in a hot filament chemical vapor deposition
(HFCVD) reactor. A mixture of gases containing hydrogen, oxygen or hydrogen and methane
mixed with water vapor were passed into a quartz glass jar reactor and activated using a heated
tungsten filament. The resulting deposits were characterized by transmission electron
microscopy (TEM), x-ray diffraction (XRD), and Raman Spectroscopy. The deposit consisted of
tungsten oxide nanorods (5 – 10 nm diameter and 50 – 75 nm long) and tungsten nanospheres
with diameters of ~50nm. The tungsten oxide is then reduced to metallic tungsten by annealing
in a hydrogen environment.
Diamond Loudspeaker Cones for High-End Audio Components
Authors: Wörner Eckhard , Wild Ch. , Müller-Sebert W. , Koidl P. , Bankewitz A.
Published: March 2009

Conventional loudspeaker membranes made of metal or synthetic material such as fabric, ceramics
or plastics suffer from nonlinearities and cone breakup modes at fairly low audio frequencies. Due
to their mass, inertia and limited mechanical stability the speaker membranes made of conventional
materials cannot follow the high frequency excitation of the actuating voice-coil. Low sound
velocity causes phase shift and sound pressure losses due to interference of adjacent parts of the
membrane at audible frequencies.
Therefore, loudspeaker engineers are searching for lightweight but extremely rigid materials to
develop speaker membranes whose cone resonances are well above the audible range. With its
extreme hardness, paired with low density and high velocity of sound, diamond is a highly
promising candidate for such applications.
We report on the realization of dome shaped CVD diamond membranes by deposition on curved
silicon substrates. Domes with diameters between 20 and 65 mm and with a thickness ranging from
50 to 120 μm were prepared. After deposition, the substrate is dissolved and the rim of the diamond
dome is cut by laser scribing. Free standing diamond membranes are mounted onto dynamic voice
coils and integrated into tweeter and/or midrange driver chassis. Extended tests and optimisations
led to loudspeaker systems that show a second and third harmonic distortion behaviour in the
important frequency range between 3 to 10 kHz that is reduced by 40% in comparison to already
excellent established values obtained with sapphire membranes. Cone resonance frequencies of
CVD diamond membranes are increased by a factor of two, as predicted by simulations.
Nanocrystalline Diamond Films by Bias Enhanced Nucleation and Argon Assisted Growth in a HFCVD System
Authors: Dikonimos Makris Th. , Falconieri Mauro , Gianoglio Stefano , Giorgi L. , Giorgi R. , Lisi Nicola , Salernitano Elena
Published: March 2009

The achievement of nanosmooth, ultrathin diamond coatings with nanosized grains is mandatory for the successful utilization of diamond in areas such as microelectromechanical systems, field emission and surface acoustic waves devices. The bias enhanced nucleation technique (BEN) allows to achieve high nucleation density diamond films, where the average distance between diamond nuclei can be as low as 10-20nm. Moreover by diluting the gas precursors (H2 and CH4) into noble gas (Ar, He) during growth, the formation of larger crystals can be inhibited, giving rise to nanocrystalline films without a degradation of the film quality, such as the presence of more graphitic bonds. In this paper we report the growth of ultrathin, smooth, high quality nanodiamond films obtained by combining the two techniques in a HFCVD reactor. A variety of nanocrystalline diamond films with a grain size as low as 10nm and thickness up to 1μm were obtained. The nucleation process and ensuing growth of the film were monitored by SEM observation. Spectroscopic measurements were also performed to study the microstructure and to assess the quality of the deposited material.
Influence of Temperature on Nano-Graphene Structuring of PLD Grown Carbon Films - An X-Ray Diffraction Study
Authors: Scilletta Claudia , Servidori Marco , Barba L. , Cappelli E. , Orlando S. , Ascarelli P.
Published: March 2009

The physical properties of graphene nano-structures are highly anisotropic and generally
correlated to the graphene sheet orientation. We investigated the capability to grow nano-graphene
structured carbon films and to control their texturing by pulsed laser ablation of a pyrolytic
graphite target (Nd:YAG laser, 2nd harmonic: λ=532 nm, hν=2.33 eV, τ=7 ns, ν=10 Hz, φ=7
J/cm2), operating at different temperature conditions. Carbon films were deposited on Si <100>
substrates. Detailed characterisation by synchrotron X-ray measurements were performed on
samples deposited in vacuum (~10-3 Pa) at high substrate temperatures (>800°C) and at room
temperature followed by post-annealing at high temperature (>800°C). The X-ray measurements
established the formation of nano-sized graphene structures for both sample sets. In the first set, the
nano-particles are correlated among them, their size increases with substrate temperature and a
longitudinal growth of parallel graphene layers occurs, with the ˆc axis parallel to the substrate. In
post annealed sample set, on the contrary, the nano-particles size is smaller and depends weakly on
annealing temperature. The graphene ˆc axis results to be randomly oriented up to ~850°C. Above
this temperature it seems that a transition phase occurs and the c axis results to lie parallel to
substrate plane.
Microplasma Synthesis of Carbon Nanostructured Materials
Authors: Terashima Kazuo , Tomai Takaaki , Ishihara Daisuke , Shimizu Yoshiki , Sasaki Takeshi , Koshizaki Naoto , Sakurai Takeki
Published: March 2009

In this study, we present our recent work on microplasma synthesis in liquid (or liquid solution)
and supercritical fluid (SCF) for carbon nanostructured materials. For microplasma synthesis in
liquid (or liquid solution), we easily fabricated graphites, carbon nano-onions, carbon nanotubes
(CNTs) and distinctive self-organized carbon nanostructures. On the other hand, for microplasma
synthesis in supercritical CO2 (scCO2), carbon nanostructured materials, such as CNTs and carbon
nanopolyhedrons, were synthesized with the arc plasma using sc CO2 as a processing medium and
raw starting material. Additionally, we showed the film deposition of carbon nanostructured
materials by using a dielectric barrier discharge under scCO2 environments.
In Vitro Reactivity of Bioactive Glass Fibers
Authors: Arstila Hanna , Tukiainen Mikko , Hupa Leena , Ylänen Heimo O. , Kellomäki Minna , Hupa Mikko
Published: March 2009

Implants with long lasting bioactivity and mechanical sustainability would be of interest
in several novel clinical applications. By processing bioactive glass fibers and biodegradable
polymers into 3D structures, bone formation ability of glasses and flexibility of polymers can be
combined. In order to achieve desired physiological response, reactivity of bioactive glass fibers
must be specified. Bundles of fibers within the range of bioactivity were soaked in the simulated
body fluid at stationary conditions for several time intervals after which the cross-sectional surfaces
of the fibers were studied with SEM-EDXA. The reaction layers and precipitations formed on the
fiber surfaces suggest that the fibers react according to three mechanisms depending on the glass
composition. Fibers with a high in vitro bioactivity showed the formation of distinct and thick silica
–rich and calcium phosphate –rich layers already at one day’s immersion. Fibers of medium
bioactivity did not show any clear silica –rich layer but a formation of calcium phosphate
precipitations or layers at one day’s immersion. Slow glasses showed sporadic calcium phosphate
precipitation only after the longest immersion times. The results indicate that the medium and slow
glasses are interesting alternatives for applications where a long term mechanical durability
suggested by their slow reactivity in combination with their osteoconductive tendency is desired.
Chemical Diversity of Apatites
Authors: Rey Christian , Combes Christèle , Drouet Christophe , Sfihi Hocine
Published: March 2009

Apatites can accommodate a large number of vacancies and afford multiple ionic
substitutions determining their reactivity and biological properties. Unlike other biominerals they
offer a unique adaptability to various biological functions. The diversity of apatites is essentially
related to their structure and to their mode of formation. Special charge compensation mechanisms
allow molecular insertions and ion substitutions and determine to some extent their solubility
behaviour. Apatite formation at physiological pH involves a structured surface hydrated layer
nourishing the development of apatite domains. This surface layer contains relatively mobile and
exchangeable ions, and is mainly responsible for the surface properties of apatite crystals from a
chemical (dissolution properties, ion exchange ability, ion insertions, molecule adsorption and
insertions) and a physical (surface charge, interfacial energy) point of view. These characteristics
are used by living organisms and can also be exploited in material science.
Haemocompatible Coatings of Coronary Stents
Authors: Bognár Eszter , Ring György , Albrecht Katalin , Dobránszky János , Ginsztler János
Published: March 2009

The main goal of the present study was to determine the surface features, surface failures
and fatigue properties of coated coronary stents. The quality and the changing of the coatings were
examined by different methods. In this paper, the results of the examinations with different coated
coronary stents are introduced and the results of the coating experiments are shown as well.
Biphasic Calcium Phosphate Granules Concept for Injectable and Mouldable Bone Substitute
Authors: Daculsi Guy
Published: March 2009

The development of calcium phosphate ceramics and other related biomaterials for bone graft
involved a better control of the process of biomaterials resorption and bone substitution. The
biphasic calcium phosphate ceramics (BCP) concept is determined by an optimum balance of
the more stable phase of HA and more soluble TCP. The material is soluble and gradually
dissolves in the body, seeding new bone formation as it releases calcium and phosphate ions
into the biological medium
The main attractive feature of BCP ceramic is their ability to form a direct bond with the host
bone resulting in a strong interface. The formation of this dynamic interface is the result of a
sequence of events involving interaction with cells; formation of carbonate hydroxyapatite
CHA (similar to bone mineral) by dissolution/precipitation processes. At the present time,
BCP is commercially available in blocks, particulates, customized design. The need of
material for Minimal Invasive Surgery (MIS) induced the development of a concept of
granules combination with polymer or calcium phosphate cement for injectable/mouldable
bone substitutes. Four types of injectable/mouldable bone substitutes have been developed by
INSERM Nantes University.
Composites in Aerospace Industry
Authors: Cavalier Jean Claude , Berdoyes Isabelle , Bouillon Eric
Published: March 2009

Since more than twenty five years, composite materials have been with continuously
increasing spatial and aeronautical applications requirements. The thermostructural composites
materials are of utmost importance for satisfying the needs of mechanical and thermal characteristics
at very high temperature and in severe environments. This paper deals with a large variety of
applications concerning the aerospace and nuclear applications like nozzles and hot gas valves for
Solid Rocket Motor (SRM), brake disks for planes, aerospace turbine engine exhaust nozzles,
thermal protection system for reentry vehicles, but also Divert and Attitude Control System (DACS)
for interceptors, heat exchangers for hypersonic propulsion systems, plasma facing components for
nuclear fusion applications and special components for nuclear fission applications. We will see that
Carbon/Carbon and Ceramic Matrix Composites are leading candidate materials for these hightemperature
structural applications. This lecture will identify the current state-of-the-art and new
technological developments. A description of the main steps of the manufacturing processes will be
made.
Lightweight Engineering with Advanced Composite Materials - Ceramic and Metal Matrix Composites
Authors: Gadow Rainer
Published: March 2009

Light weight engineering by materials and by design are central challenges in modern
product development for automotive applications. High strength structural ceramics and
components were in the focus of R & D in automobile development since the 1970's and CMC have
dominated advanced materials engineering in aerospace applications. The limiting factor for their
market acceptance was the high processing and manufacturing cost. The automotive industry
requires technical performance and high economic competitiveness with tough cost targets. The
potential of ceramic matrix composites can be enhanced, if new fast and cost effective
manufacturing technologies are applied. This is demonstrated in the case of SiC composites for
high-performance disk brake rotors for passenger cars.
Light metal composites are promising candidates to realize safety relevant lightweight
components because of their high specific strength and strain to failure values, if their stiffness and
their thermal and fatigue stability is appropriate for the application, i.e. in power train and wheel
suspension of cars. Tailor-made fiber reinforcements in light metal matrices can solve this problem,
but the integration of fibers with conventional manufacturing techniques like squeeze casting or
diffusion bonding leads to restrictions in the component's geometry and results in elevated process
cost mainly caused by long cyc1e times and the need of special tools and additional fiber coatings.
A new manufacturing method for metal matrix composites (MMC) made by fast thixoforging is
introduced. Thereby, prepregs consisting of laminated fiber woven fabrics and metal sheets or,
alternatively, thermally sprayed metal coatings on ceramic fiber fabrics are used as preforms for an
advanced thixoforging process for the manufacturing of Al-Si MMC components in mechanical
engineering.
Advances in SiC Fibers for High Temperature Applications
Authors: Ichikawa Hiroshi
Published: March 2009

The oxygen free SiC fiber (Hi-Nicalon) has been commercially produced by an electron
beam curing process. And then the SiC fiber (Hi-Nicalon Type S) having stoichiometric SiC
composition and high crystallinity has been developed.
Hi-Nicalon fiber has higher elastic modulus and thermal stability than Nicalon fiber. The Type S
fiber has the highest elastic modulus and thermal stability and excellent creep resistance in three
types of Nicalon fibers.
Recently，Type S fibers as industrial products have been developed and put on the market.
The Type S fibers have a high tensile strength of 2.8 GPa, a high elastic modulus of 390 GPa.
Against thermal exposure, Type S retains a tensile strength of 2.3 GPa and hardly changes its elastic
modulus even at 1873K. Moreover, Type S has outstanding creep resistance. Type S shows higher
stress relaxation ratio than many other ceramic fibers after thermal exposure over 1673K.
Now, Hi-Nicalon Type S fiber/BN/SiC composites are being developed as the components of gas
turbine for aerospace and land based power generation such as shrouds and combustors.
Type Hi-Nicalon S can be supplied about 30 kg per a month at present.
Advanced Composite Materials for Current and Future Propulsion and Industrial Applications
Authors: Beyer Steffen , Schmidt Stephan , Maidl Franz , Meistring Rolf , Bouchez Marc , Peres Patrick
Published: March 2009

Various technology programmes in Europe are concerned with preparing for future propulsion
technologies to reduce the costs and increase the life time of components for liquid rocket engine
components. One of the key roles to fulfil the future requirements and for realizing reusable and
robust engine components is the use of modern and innovative materials. One of the key
technologies which concern various engine manufacturers worldwide is the development of fibrereinforced
ceramics – CMC's (Ceramic Matrix Composites). The advantages for the developers are
obvious – the low specific weight, the high specific strength over a large temperature range, and
their good damage tolerance compared to monolithic ceramics make this material class extremely
interesting as a construction material.
Different kind of composite materials are available and produced by EADS ST, the standard
material SICARBON® (C/SiC made by Liquid Polymer Infiltration) and the new developed and
qualified composite materials SICTEX® (C/SiC made by Liquid Silicon Infiltration) and
CARBOTEX® (C/C made by Rapid Chemical Vapour Infiltration). The composites are based on
textile techniques like weaving, braiding, stiching and sewing to produce multiaxial preforms, the
SICTEX® material is densificated by the cost effective Liquid Silicon Infiltration (LSI).
Over the past years, EADS Space Transportation (formerly DASA) has, together with various
partners, worked intensively on developing components for airbreathing and liquid rocket engines.
Since this, various prototype developments and hot firing-tests with nozzle extensions for upper and
core stage engines and combustion chambers of satellite engines were conducted. MBDA France
and EADS-ST have been working on the development of fuel-cooled composite structures like
combustion chambers and nozzle extensions for future propulsion applications.
Micromechanics-Based Evaluation of Interfaces in Ceramic Matrix Composites
Authors: Lamon Jacques , Pompidou Stephane
Published: March 2009

Interfaces are a key element in ceramic matrix composites, but also in several material
assemblies, such as, for instance, multilayers. This is not only because they can cause crack
deflection and make materials damage tolerant, but also because they can be tailored with regard to
material performances.
An approach to crack deflection at interfaces or within interphases is proposed on the basis of
the following Cook and Gordon’s mechanism: a crack is nucleated along an interface, ahead of a
propagating crack; deflection of this crack then results from coalescence with the interface crack.
The stress state induced by a crack was computed in a cell of bimaterial using the finite element
method. The cell represents a matrix and a fiber, or an interphase and a fiber or two layers in a
multilayer. A master curve was established. It represents the debonding condition based on
strengths and elastic moduli of constituents. Then a deviation potential was defined. Deviation
potentials were calculated for various fibre/matrix or layer combinations.
Thixoforged Al-Si Metal Matrix Composites Made from Thermally Sprayed Ceramic Fiber Laminates
Authors: von Niessen Konstantin , Wenzelburger Martin , Gadow Rainer
Published: March 2009

Advanced continuous fiber reinforced light metal matrix composites (MMC) are
manufactured using thermally sprayed prepregs and subsequent semi-solid forming. The prepregs
consist of fiber woven fabrics, which will serve as reinforcement, and a thick metal alloy coating on
top of the fabrics as the final matrix material. The coated fabrics are trimmed to the shape of the
component and laminated in packages of 40 to 80 prepregs to form a component. The prepregs are
reheated into the semi-solid state of the alloy and solidified to a dense, complex shaped MMC with
no residual porosity by semi-solid forging (thixoforging). The deposited alloy infiltrates the fabrics
with 40 % vol. to 60 % vol. liquid fraction. The fine-grained structure of the thermally sprayed
metal coatings allows the required formation of globular grains during remelting and improves the
impregnation behavior. The semi-solid forming and simultaneous infiltration in short cycle times
offer the possibility to realize complex near net-shape geometries and make additional fiber coating
not obligatory. A pilot plant was developed to provide the MMC production with prepregs
consisting of various reinforcement fiber materials and a wide range of metal matrix alloys capable
for thixoforging densification.
CMC-Processing from Powders by Hot-Pressing
Authors: Dong Shao Ming , Ding Yu Sheng , Wang Zhen , Zhou Qing , Zhang Xiang Yu , Jiang Dong Liang , Kohyama Akira
Published: March 2009

Hot pressing is an effective way to densify powder compacts, especially during the
inclusion of a second phase, such as particles, whiskers or fibers. In the present study, SiC/SiC and
C/SiC composites were prepared by hot pressing via liquid phase sintering. Nano-SiC powder was
used for matrix formation with sintering additives. The effects of preparation conditions such as
sintering temperature, pressure and matrix composition, on the microstructural evolution and
mechanical behaviors were discussed. Using micro-SiC powder and nano-SiC powder for matrix
formation, the interaction between fiber and matrix was characterized. Because the matrix
compositions can be easily modified in the CMC-processing from powders by hot pressing, the
SiC-BN matrix was also studied in the present experiment. The inclusion of BN can either improve
the machinability or provide oxidation resistance to the composite. BN was derived through an in-situ
reaction between boron acid and urea by hot-pressing. Boric acid and urea were solved into the
ethanol and mixed with nano-SiC particles, and then infiltrated into the fiber bundles. Correlations
among microstructures, properties and compositions will be discussed.
Patterned 2D and 3D Assemblies of Nanoparticles on Molecular Printboards
Authors: Huskens Jurriaan
Published: March 2009

Functionalized nanoparticles have powerful applications as intermediates between
solution and surface chemistry and as tools for nanofabrication. Two main examples of these have
been shown. The functionalization of 3 nm gold and 55 nm silica nanoparticles with cyclodextrin
(CD) host sites has been achieved, which allows: (i) the controlled aggregation with guestfunctionalized
dendrimers in solution, (ii) the specific adsorption onto dendrimer-patterned
substrates, and (iii) the fabrication of larger architectures using the layer-by-layer methodology.
Aggregation in solution was shown to proceed through specific host-guest recognition. The
adsorption onto surfaces employed so-called “molecular printboards”, which are self-assembled
monolayers with the same cyclodextrin host recognition sites which allow the stable assembly of
molecules and nanoparticles through multivalent host-guest interactions. CD silica nanoparticles
were shown to adsorb specifically onto areas of such molecular printboards which were patterned
with adamantyl-functionalized dendrimers. The layer-by-layer (LBL) assembly of such dendrimers
and CD gold nanoparticles led to a controllable multilayer architecture with a thickness increase of
about 2 nm per bilayer. The combination of the (bottom-up) particle LBL assembly and top-down
surface structuring, in particular nanoimprint lithography, was shown to result in the formation of
3D objects down to sub-100 nm in all three dimensions.
Some Investigations on Gallium Arsenide MEMS. Simulation of Microstructure Shapes
Authors: Tellier C.R. , Huve G. , Leblois Therese G.
Published: March 2009

A study was made on the micromachining of GaAs in a H3PO4:H2O2:H2O solution with
composition 1:9:1. In the first part etch rates and morphologies of etched structures were evaluated
in order to characterize the anisotropy. The second part was devoted to numerical simulations of 3D
etching shapes. For this purpose the database of the simulator TENSOSIM was determined.
Comparison of theoretical 3D etching shapes with experimental shapes of micromachined structures
supports the validity of the proposed database. So the simulator TENSOSIM is a convenient CAO
tool for the design of new GaAs MEMS.
Dependence of Adhesion and Reflection on Orientation in Nanocluster Deposition
Authors: Hendy Shaun C. , Awasthi Aruna
Published: March 2009

We consider the deposition of icosahedral clusters on a weakly adhesive substrate using
molecular dynamics. We identify three characteristic orientations that lead to distinct collision
behavior: vertexfirst,
edgefirst
and facetfirst.
At low velocities, the collision depends strongly on
cluster orientation with vertexfirst
collisions leading to reflections and edgefirst
collisions leading
to adhesion. At high velocities, the collisions depend only weakly on orientation with the majority of
collisions leading to reflection.
In Situ Observation of Quantized Growth of Titanium Silicide in Ultra High Vacuum Transmission Electron Microscope (UHV-TEM)
Authors: Hsin Cheng Lun , Wu Wen Wei , Hsu Hung Chang , Chen Lih Juann
Published: March 2009

Dynamic study of the growth of TiSi2 nanorods on Si bicrystal was conducted in
an ultrahigh vacuum transmission electron microscope. The growth of the nanorods
was affected by the underlying dislocation grids significantly. The dislocation grids
confined the shape of the nanoclusters and nanorods. Compared to the time of the
nanorod remaining at the same length, the elongating time is relatively short. The
dislocation network confined the nanorod to match the dislocation interspacing and
the step-wise growth of the nanorod was found. The growth mechanism is attributed
to the compliant effect. The observation was constructive to the basic understanding
of the stress effect on the initial stage of the reaction of metals on Si.
Nanotubes Based Composites for Energy Storage in Supercapacitors
Authors: Frackowiak Elzbieta
Published: March 2009

Composites based on nanotubes with such active materials as conducting polymers (e.g.
polyaniline, polypyrrole), transition metal oxides (manganese oxide) and carbons enriched in
heteroatoms (e.g. nitrogen) have been considered as electrodes for supercapacitors.
The open mesopores network formed by the entanglement of nanotubes permits the ions to diffuse
easily to the active surface of the composite components, hence, a good charge propagation and
high values of capacitance (100-350 F/g) have been obtained. Since nanotubular materials are
characterized by a high resiliency, the composite electrodes can easily adapt to the volumetric
changes during charge/discharge, that drastically improves the cycling performance of
supercapacitors.
Additionally, it has been proved that combining materials with pseudocapacitance properties in an
asymmetric configuration is a very promising direction for developing a new generation of high
performance supercapacitors.
Nanocrystals in High-k Dielectric Stacks for Non-Volatile Memory Applications
Authors: Fanciulli Marco , Perego Michele , Bonafos Caroline , Mouti A. , Schamm S. , Benassayag G.
Published: March 2009

The possibility to use semiconducting or metallic nanocrystals (ncs) embedded in a
SiO2 matrix as charge storage elements in novel non volatile memory devices has been widely
explored in the last ten years. The replacement of the continuous polysilicon layer of a
conventional flash memory device by a 2-dimensional nanoparticle array presents several
advantages but the fundamental trade-off between programming and data retention characteristics
has not been overcome yet. The main problem is the limited retention time basically due to charge
loss by leakage current through the ultra-thin SiO2 tunnelling dielectric. A longer retention time
can be achieved by increasing the tunnel oxide thickness. This however implies higher operating
voltages and consequently a reduced write/erase speed. Using high-k materials for tunnel and/or
gate oxide it is in principle possible to achieve the goal of a low voltage non volatile memory
device. The high dielectric constant of these materials allows using thicker tunnel oxide reducing
leakage current. Several approaches have been explored to synthesise ordered arrays of ncs in
SiO2 but the transfer of these methodologies to the synthesis of 2-d array of ncs in high-k materials
is not trivial. In this work we address the material science issues related to the synthesis of
metallic and semiconducting ncs in high-k materials using different techniques. A detailed review
of the state of the art in the field is presented and further research strategies are suggested.
LGS and LGN Microresonators: Applications to High Temperature Nanobalances
Authors: Leblois Therese G.
Published: March 2009

New materials such as langasite and langanate crystals present some interesting
perspectives for acoustic wave devices due to strong piezoelectric coefficients and due to the
opportunity to work through a wide range of temperature. Theoretical formulations for temperature
coefficients and electromechanical coupling coefficients of resonators are given in the case of
thickness modes of vibration. Results are computed using two data sets of elastic, piezoelectric and
dielectric constants. Orientations of BAW microresonators which give zero frequency shift versus
temperature at 600°C are determined to serve as high temperature nanobalances.
Humidity Sensors Based on Nanostructured Materials
Authors: Krutovertsev S. , Tarasova A. , Krutovertseva L. , Zorin A. , Ivanova O.
Published: March 2009

Constraction and characteristics of sorption polymeric relative humidity sensors, sorption
SiOx microhumidity sensors, and condensation type (dew point) sensors are compared. The
characteristics of the sensors are examined in dew point range from -80 to +20oC. An integrated
multifunctional humidity sensor, for measurements in wide humidity range at different conditions is
developed. The sensors are intended for use in various branches of industry, and in scientific
researches.