bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Noble Metal Particles on Redox Reactions on Uranium Dioxide Surfaces
Authors: Broczkowski M.E. , Goldik J.S. , Noël J.J. , Shoesmith David
Published: March 2009

The influence of rare-earth doping and noble metal inclusions (ε-particles) on H2O2 and O2
reduction and H2 oxidation on UO2 surfaces has been studied electrochemically. These reactions
are important in determining the corrosion behaviour of nuclear fuel inside failed waste containers
under permanent waste disposal conditions. Experiments were conducted on SIMFUEL electrodes
doped with various amounts of non-radioactive elements in proportions appropriate to simulate the
chemical effects of in-reactor irradiation. The results show that ε-particles catalyze all of these
reactions. These results indicate that ε-particles can act as catalytic anodes and cathodes depending
on the redox conditions prevailing within a failed container.
Direct Oxidation of Dry Methane by Pd-Ni Synergy Catalyst Supported on Lanthanum Chromite Based Anode
Authors: Yamanaka Ichiro , Nabae Yuta
Published: March 2009

Steady generation of electricity (360 mW cm-2 at 1173 K) with dry methane fuel was
successfully performed in solid oxide fuel cells (SOFC) by Pd-Ni bimetallic catalyst on porous
composite anode prepared from La0.8Sr0.2CrO3 (LSCr) and Ce0.8Sm0.2O1.9 (SDC) (50:50 wt%). The
amounts of carbon deposition were quite small under the open and closed circuit conditions. Synergy
of Pd and Ni electrocatalysts was observed on the LSCr-SDC anode for the oxidation of dry methane.
A small amount of carbon deposition over the anode during the open circuit conditions could be
easily and quickly removed by gasification with steam. Data of detailed kinetic studies and
electrochemical analysis strongly suggest that (i) methane decompose to hydrogen and carbon over
the Pd-Ni catalyst, (ii) hydrogen is electrochemically oxidized with O2- to water, and (iii) carbon is
quickly reformed with water to hydrogen and carbon oxides.
Methane Reforming Deposit by Suspension Plasma Spraying
Authors: Guénadou David , Bianchi Luc , Puzenat Eric
Published: March 2009

Suspension plasma spraying consists in the injection of liquid/nanopowder mixture into a
plasma jet. The interest of this technique is to create nano-structured and thin coatings. The porous
structure made has a wide specific surface area and is very attractive for catalytic application. This
article is devoted to present our works on La0.75Sr0.25Cr0.5Mn0.5Ox doped rhodium deposits used for
reforming methane. The first part presents the spraying operation and the second part, the results in
term of microstructure and reforming performance.
Ceramic Brick with High Water Retentivity Prepared from Ceramic Waste and by Products
Authors: Sugiyama Toyohiko , Nagae Hajime , Suzuki Kazuo , Nakano Kenichi
Published: March 2009

Many kinds of industrial waste were examined as potential constituents of ceramic bricks
or tiles. The basic physical properties of these materials were measured, such as sintering
temperature, water absorption, porosity, density, color, chemical stability and bending strength.
Several kinds of sintered ceramics containing large amounts of waste materials were obtained by
adjusting the amount of the waste materials added to the ceramics. These were fired at temperatures
lower than 1000°C. A lowering of firing temperature results in a reduction of discharge of CO2 on
the production process. Ceramic brick with high water retention is expected to mitigate the heatisland
phenomenon by the latent heat of evaporation. Porous ceramics were prepared using
industrial waste, burned ash and recycled roofing tile as raw materials. The permeability, water
retentivity, water absorption, and other properties of the porous recycled ceramics were investigated.
The pF value of the ceramics was measured as an indicator of water retentivity. An appropriate
method of characterizing water retentive ceramic materials was also discussed based on results of
fundamental examination of the ceramics under practical conditions.
Next Generation Carbon-Containing Refractory Composites
Authors: Zhang Shao Wei
Published: March 2009

Carbon-containing refractory bricks are used extensively in the
steel industry worldwide. Since the first generation became commercially
available in the 1970’s, their processing, microstructures and properties have
been improved dramatically, and the service lives of industrial furnaces have
thus been extended substantially. In addition to the work on carboncontaining
refractory bricks, much effort has been, and is being, made
worldwide towards the development of carbon-containing refractory
castables. In this paper, the latest R & D towards new generation carboncontaining
refractory bricks as well as carbon-containing refractory castables
have been highlighted. In the first part, current techniques used to improve
mechanical properties of carbon-containing refractory bricks are
summarised. A new concept using a catalytic-growth technique to create insitu
oxide nanofibres and/or carbon nanotubes in carbon-containing
refractory bricks is introduced. The second part addresses some important
technical issues of low carbon carbon-containing refractory bricks. Besides
the concern about thermal shock resistance, other new problems arising
from the use of nanosized carbon, such as the accelerated MgO-C reaction
and carbon oxidation, are discussed. In the final part of the paper, technical
difficulties hindering the development of carbon-containing castables as
well as measures to overcome them are discussed. A novel molten salt
synthesis technique developed recently at Sheffield to prepare high quality
carbide coatings on graphite is introduced.
Research on the Fabrication of BaTiO3-Based PTCR Materials and Thermistors by Polyacrylamide Gel Process
Authors: Zheng Zhi Ping , Gong Shu Ping , Zhou Dong Xiang
Published: March 2009

BaTiO3-based powders used for positive temperature coefficient of resistance (PTCR)
were synthesized by polyacrylamide gel process. The effect of synthesis conditions such as the pH of
the citrate solutions and the reticulation of the polyacrylamide gel on the objection phase was
investigated. The results showed that when the citrate solutions had a neutrality pH of 7~8 and the
polyacrylamide gel was hard reticulated, precursor powder with pure and completely crystallized
objection phase was obtained at calcination temperature of more than 700°C. The results of XRD and
TEM revealed that precursor powder had an average grain size of about 50 nm. Compared with those
prepared by solid-state reaction, PTCR ceramics prepared by polyacrylamide gel process have one
magnitude higher ratio of maximum to minimum of resistance and low sintering temperature, which
provides a practical and theoretical foundation for preparing multilayer PTCR thermistors by
co-firing of semiconducting BaTiO3 ceramics and electrode.
Relaxor Single Crystals with Giant k31 Mode
Authors: Ogawa Toshio
Published: March 2009

Giant electromechanical coupling factor of k31 mode over 86% was found for (100)
Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 and (110) Pb[(Mg1/3Nb2/3)0.74Ti0.26]O3 single-crystal plates poled in the
[100] and [110] directions, respectively. The P-E hysteresis loops in the single-crystal plates with
giant k31 became asymmetric. Furthermore, the frequency response of impedance in these plates with
giant k31 consisted of a single vibration in the length direction. A mechanism to realize giant k31 can
be explained by the relationship between the crystal plane and poling direction. In addition, the
existence of giant piezoelectric d31 constant was proven by the strain measurement as well as by the
impedance measurement.
Piezoelectric Ceramics Based on Perovskite Solid Solutions with MPB - Mechanochemical Activation and Texturing for High Sensitivity and Power
Authors: Algueró Miguel
Published: March 2009

Ceramics of morphotropic phase boundary (MPB) Pb(Mg1/3Nb2/3)O3-PbTiO3 have been
processed from powders synthesized by mechanochemical activation of oxides. Their properties
have been characterised and are compared with those of a MPB Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramic
material by the columbite route. Current experiments on texturing by templated grain growth from
the powders synthesised by mechanochemical activation are briefly described. MPB
Pb(Zn1/3Nb2/3)O3-PbTiO3 has also been mechanosynthesised, though perovskite is not stable under
heating and ceramics cannot be processed. Pb(Fe1/2Nb1/2)O3 is being investigated as a means of
stabilising the perovskite, and MPB ceramic materials of the ternary system have been successfully
prepared.
Characteristics of (1-y)[(Na0.5Bi0.5)1-xBax]O3-yBa(Cu1/2W1/2)O3 Ceramics Prepared by Hydrothermal Synthesis Route
Authors: Zhou Dong Xiang , Li Hui , Deng Yi Hua
Published: March 2009

(Na0.5Bi0.5)TiO3 (Abbreviated to BNT) was synthesized by hydrothermal process and the
average gain size was 15 nm with narrow size distribution. Pure perovskite structure of BNT particles
was identified by XRD analysis. The nanoscale BNT powder was selected as raw material to fabricate
BNT based ceramics with BaTiO3 (Abbreviated to BT) and Ba(Cu0.5W0.5)O3 (Abbreviated to BCW)
doping. SEM images show that the ceramic using nanoscale BNT powder as raw material has a high
dense body with the average gain size from 0.5 μm to 1 μm. The experimental results show that with
increasing amount of BCW, d33 and Kp of (0.94-x)BNT-0.06BT-xBCW increase initially, then reach
the maximum values of 130 pC/N and 0.32 when 5mol% of BCW was added. Further increasing
amount of BCW leads to decreasing d33 and Kp. The optimal piezoelectric and dielectric properties
were obtained as d33 = 130 pC/N, Kp = 0.32, εr = 800, tgδ = 0.06.
Sol-Gel Bonded Piezoelectric Lead Zirconate Titanate Ceramics
Authors: Sangsubun Chontira , Watcharapasorn Anucha , Naksata Manoch , Tunkasiri Tawee , Jiansirisomboon Sukanda
Published: March 2009

The sol-gel bonded lead zirconate titanate, PbZr0.52Ti0.48O3 (PZT), ceramics were
prepared by calcining and sintering at high temperatures the mixture between a conventional mixedoxide
powder and a sol from a triol sol-gel method. The effects of sintering condition on phase
formation, microstructures and dielectric properties were investigated and compared with the
conventional and sol-gel PZT ceramics. X-ray diffraction analysis indicated that, in the ceramics
containing sol-gel powder, the crystal structure changed from tetragonal to rhombohedral phase as
the sintering temperature increased from 1150°C to 1200°C. This change in crystal structure also
affected the microstructure of the ceramics. The dielectric constants at Tc of the sol-gel ceramics
were found to be greatest and this suggested a possible use of sol-gel powder to produce PZT
ceramics for high temperature applications.
Novel Synthesis for Ultrafine Barium Titanate Powders Using Peptized Titania Nano-Sol
Authors: Lee Jai Joon , Kim Jun Tae , Park Kum Jin , Hur Kang Heon , Koo Sang Man
Published: March 2009

We have investigated a novel synthesis for highly spherical and ultrafine barium titanate
(BaTiO3) powders using a peptized titania (TiO2) nano-sol as a precursor. The obtained TiO2
nano-sol had the size less than 10 nm, which could be easily converted to BaTiO3 under 100 °C. The
size of the resulting BaTiO3 powder could be controlled from 42 to 167 nm by lowering the solution
concentration from 1.00 M to 0.15 M. BET analysis indicated that the as-prepared BaTiO3 powders
had some porosity which was increased with the particle size. It was also found that the as-prepared
BaTiO3 with smaller size had higher tetragonality and less intra-granular pores after annealing.
Complex Permeability of Ferrites Correlated with their Microstructure
Authors: Jankovskis Janis
Published: March 2009

The totality of spinel and garnet polycrystalline ferrite (PF) samples is divided in two
subgroups in process of their complex initial permeability (including the static value) relating to
their microstructure (MS). The analysis for the first, including PF of rather perfect MS brings to
explicit relations showing the effects of grain size distribution. For the other, the group of typical
PF, the observed effects is possible to evaluate basing on the results gained for the first group.
Development of a Super Broadband RF Splitter Using Bead Type Ferrite Core Transformers
Authors: Kanie Takahito , Kato Hiroaki , Noro Y. , Takeo T.
Published: March 2009

We report on the broadening of the operating frequency of a RF splitter widely used in
CATV systems. In order to realize this, the relationship between the splitter’s transmission
characteristics and design parameters has been investigated using computer-aided engineering.
Based on the calculations, a sample device has been fabricated to confirm the theoretical results. It
has been found that by selecting the parameters appropriately, excessive loss can be suppressed to
less than 1.6dB and 3dB in a frequency range of 20MHz to 2,600MHz in the cases of 2-way and
4-way splitters, respectively.
Size and Surface Control of Optical Properties in Silicon Nanoparticles
Authors: Fabbri F. , Borsella Elisabetta , Carpanese M. , Fantoni Roberta , Caterino R. , D'Amato Rosaria , Falconieri Mauro , Serra Emanuele
Published: March 2009

Si-nanoparticles (NP) are attracting steadily growing interest due to their intriguing sizedependent optical properties. The most challenging task in preparing Si-NP is to succeed in controlling the particle size and size distribution and the surface properties. To this respect, the method of laser synthesis of Si-NP from gas phase reactants appears as an ideal tool, being a very versatile and controllable synthesis technique, but the collected Si-NP are strongly agglomerated. Here we report on attempts to decrease the agglomeration of the Si NP by following two complementary strategies: - investigation and control of nanoparticle formation and growth during the synthesis process; - dispersion of the agglomerates and termination of the particle surfaces by controlled chemical etching followed by surface passivation and stabilization treatments. The properties of as-prepared and processed Si NP will be presented and discussed.
Magnetization Reversal by Spin-Polarized Current in Magnetic Tunnel Junctions with MgO Barriers
Authors: Kubota Hitoshi , Fukushima A. , Ootani Y. , Yuasa S. , Ando K. , Maehara H. , Tsunekawa K. , Djayaprawira D.D. , Watanabe N. , Suzuki Y.
Published: March 2009

Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions were fabricated using UHV magnetron
sputtering. Magnetoresistance and spin-transfer switching properties were investigated as a function
of Co-Fe-B free layer thickness, between 1.5 nm and 3 nm. The intrinsic switching current and
the thermal stability were derived from the pulse duration dependence of the switching current,
analyzed based on the thermally activated switching model. Both switching currents, corresponding
to parallel (P) to antiparallel (AP) (Ic0
+) and AP to P (Ic0
–) magnetization reversal, were found
to be roughly proportional to the free layer thickness. The averaged intrinsic switching current
density Jc0
av = (Ic0
+–Ic0
–)/(2A) (where A is the cell area) was in the range of 1–2×107 A/cm2. The
experimental values of Jc0
±
agreed with theoretical values, determined taking into account the spintransfer
efficiency for the case of magnetic tunnel junction. The thermal stability of the P and AP
states was different, but roughly proportional to the free layer thickness in both cases. We attribute
this difference to a disparity in the net magnetic field acting on the free layer magnetization in the P
and AP states. The average of the thermal stability in the two states varied from 30 to 60 when the
free layer thickness was increased. According to our findings, to guarantee the non-volatility of an
MRAM device for about 10 years, the Co-Fe-B free layer should be thicker than 2 nm.
Growth and Property Characterization of Epitaxial MAX-Phase Thin Films from the Tin+1(Si, Ge, Sn)Cn Systems
Authors: Högberg H. , Emmerlich J. , Eklund P. , Wilhelmsson Ola , Palmquist Jens Petter , Jansson Ulf , Hultman L.
Published: March 2009

Epitaxial Mn+1AXn phase (n=1, 2 or 3) thin films from the chemically related Ti-Si-C, Ti-Ge-C, and
Ti-Sn-C systems were grown on Al2O3(0001) substrates at temperatures in the region of 700-1000
oC, using d.c. magnetron sputtering from individual sources. In addition to growth of the known
phases Ti3SiC2, Ti3GeC2, Ti2GeC, and Ti2SnC the method allows synthesis of the new phases
Ti4SiC3, Ti4GeC3, and Ti3SnC2 as well as the intergrown structures Ti5A2C3 and Ti7A2C5 in the Si
and Ge systems. Characterization by XRD, TEM and nanoindentation show similarities with respect
to phase distribution, mechanical, and electrical properties, particularly pronounced when
comparing Si and Ge. The Ti-Sn-C system is, however, the most liable system with respect to
surface segregation of the A-element. This causes less favorable growth of MAX phases as seen by
a preferential growth of the binary carbide TiC and metallic Sn. Nanoindentation on films from the
Ti-Si-C and Ti-Ge-C systems shows large plastic deformation with extensive pile up. The typical
thin film hardness is 20 GPa, and the Young’s modulus in the region of 320 GPa. The four-point
probe resistivity is low for all systems, but differs depending on materials system and phase, with
values of 25 μcm for Ti3SiC2, and 17 μcm for Ti2GeC.
Thermal Plasma Processing of Functional Ceramic Materials
Authors: Ishigaki Takamasa , Li Ji Guang , Moriyoshi Yusuke
Published: March 2009

Fe- and Eu-doped TiO2 nanocrystals were synthesized via Ar/O2 thermal plasma oxidation
of liquid precursor mists. The use of mists ensures atomic level mixing of the elements and high
supersaturation of the evaporated species upon plasma oxidation, which favors nanocrystal formation
upon condensation. Iron-doped TiO2 nanopowders with controlled iron to titanium atomic ratios
(RFe/Ti) ranging from 0 to 20%, were synthesized by oxidative pyrolysis of liquid-feed metallorganic
precursors containing titanium tetra-n-butoxide (TTBO) and ferrocene. Europium doped TiO2
luminescent nanocrystals were also synthesized via RF thermal plasma oxidation of liquid precursor
mists containing TTBO and europium nitrate.
Electrohydrodynamics and Electrokinetics of Colloidal Ceramic Gels: Fundamentals and Applications
Authors: Falk G.
Published: March 2009

Processing of colloidal gels with electrified interfaces to form ceramic bulk and composite materials
as well as coatings of complex shapes with well definded structures in the nanoscale requires the
understanding of fundamental role of the coupling between hydrodynamic and electric interactions
in colloidal deposition and colloidal arrangement.
In this article, fundamental equations of electrohydrodynamics of membrane supported electrophoretic
deposition (EPD) as well as exemplary numerical FEM-simulations of electrophoretically
deposited colloidal gels are presented. Based on microfluidic physics a model is then used to study
electrohydrodynamic EPD phenomena, especially electroosmotic flow incorporated with modulated
surface potentials, particle interactions and electrostatic potentials. Some practical applications of
EPD as well as visions of general purpose of the computational modelling results were given.
Self-Propagating High-Temperature Synthesis: Non-Equilibrium Processes and Equilibrium Products
Authors: Merzhanov A.G.
Published: March 2009

The nature of SHS process was studied, and conditions under which equilibrium and
non-equilibrium regimes take place for wave propagation and structure formation of SHS products
are under consideration. The important role of cooling down time is shown. Depending on its
magnitude, either autoannealing or autoquenching processes can take place in the products after
combustion front propagation. The correlation between transition from non-equilibrium to
equilibrium state of the product with prolongation of cooling time was examined as well as
character of products and processes was indicated in dependence on relationship between the
characteristic times of combustion, time of cooling down, and structure formation in SHS product.
3-D Structures via Tape Casting and Lamination
Authors: Roosen Andreas
Published: March 2009

Miniaturisation and multi-functionality are the driving forces in the field of many
technical market segments. Ceramic multilayer technology via tape casting and lamination is
one of the key technologies to generate complex, highly integrated devices for future applications.
The technique offers a tremendous potential for the integration of different materials
combined with the possibility to form complex 3-D structures by layered object manufacturing.
The ceramic multilayer technology is based on shaping, screen-printing and stacking of individual
ceramic green tapes, which are laminated and co-fired. The tapes can offer ferroelectric,
piezoelectric and magnetic behaviour, insulating and semi-conducting properties, voltage-,
temperature- and atmosphere-dependent resistances, high thermal conductivity, corrosion
resistance, or bio inert behaviour. For the integration of additional features like reactors or sensors,
the described layered manufacturing method allows to introduce simultaneously microchannels
and other cavities. - New developments in processing and in materials concepts are
addressed to overcome limitations and to take maximum advantage of this technique. The
technique is illustrated considering e.g. microwave circulators for communication, sensors for
automotive applications, and piezoelectric actuators as examples, which demonstrate the
potential of the technology for the manufacture of highly integrated multifunctional systems.
Development of High-Speed Centrifugal Compaction Process of Alumina
Authors: Suzuki Hiroyuki Y. , Kuroki Hidenori
Published: March 2009

High-Speed Centrifugal Compaction Process (HCP) is one of slip-using compacting method in
which the compacts are obtained as sediments under huge centrifugal force. Compacting mechanism of the
HCP differs from other slip using compacting methods. The unique compacting mechanism of the HCP leads
a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, etc.
Moreover, the most outstanding characteristics of the HCP can be found in homogeneous and flawless
microstructure of the green compacts, because the process possesses an intrinsic defect removing function.
That is, the defect inducing matters in slips (powder aggregates, inclusions, bubbles) are removed from the
main part of the compact by the classification effect of centrifuge, and therefore the HCP alumina exhibits
superior sinterabiliy and higher strength and hardness than most other aluminas. Many of the advantageous
characteristics of the HCP can be improved with a higher centrifugal force.
Shape Forming of Alumina-Silica of High Thermal Stability for Space Propulsion Applications
Authors: Amariei Daniel , Rossignol Sylvie , Kappenstein Charles
Published: March 2009

The replacement of toxic hydrazine used for catalytic propulsion by less toxic
propellants such as ionic liquids is of hot interest. The challenge for this replacement is the
formulation, development and shape forming of new catalysts. Efficient catalysts for the
decomposition of aqueous 79 wt.-% HAN solutions (hydroxylammonium nitrate NH3OH+NO3
-)
contain 10 wt.-% Pt active phase deposited on a support. Laboratory-made powder catalysts
contain platinum supported on Si-doped alumina and display a good activity at low temperature.
But, for industrial applications in propulsion thrusters, the pressure drop due to a powder is too
high and consequently shape formed supports and catalysts must be prepared and investigated.
Two catalyst types have been prepared (i) from shaped supports obtained at the laboratory level
using the “oil-drop” method and (ii) from supports formed through an industrial procedure. Both
shape formed samples display comparable properties as the powder support, such as high thermal
stability linked to the presence q and d aluminas and similar BET surface area. Catalysts based
on these supports show efficient catalytic activities.
Rheology of Ceramic Suspensions with Biopolymeric Gelling Additives
Authors: Gregorová Eva , Pabst W. , Štĕtina Jiri
Published: March 2009

An overview is given of the rheological behavior of biopolymers in aqueous suspensions
and of their role in new ceramic shaping processes (starch consolidation casting and carrageenan gel
casting). In particular, we give a state-of-the-art account of the viscometric behavior, measured via
rotational viscometry (apparent viscosity, including its shear-rate and concentration dependence),
and the viscoelastic properties characterized via oscillatory shear rheometry (storage modulus, loss
modulus and phase angle, including their temperature dependence), of starch-water systems, starchcontaining
alumina suspensions, carrageenan-water systems and carrageenan-containing zirconia
suspensions.
An Experimental Validation of a 3D Kinetic, Monte Carlo Model for Microstructural Evolution during Sintering
Authors: Tikare Veena , Braginsky Michael V. , Bouvard Didier , Vagnon Alexander
Published: March 2009

An experimental validation of a 3D kinetic, Monte Carlo model for simulation of
microstructural evolution during solid state sintering will be presented. The model – a statistical
mechanical model, which can simulate curvature-driven grain growth, pore migration, and vacancy
formation, diffusion and annihilation – is validated by comparing microstructural evolution
obtained experimentally for a copper powder compact. The 3D microstructural evolution of copper
powder particles sintering was imaged in-situ by microtomography. The images show particles with
internal porosity percolating through the particles. Microstructural features – e.g., neck formation
and growth – from the experimental images as well as the overall densification rates are compared
to the simulations.
Influence of Co-Doping on the Sintering Map of an Ultra Fine and Ultra Pure Alpha Alumina Powder
Authors: Bernard-Granger Guillaume , Guizard Christian
Published: March 2009

The sintering map of an ultra fine and ultra pure α-alumina powder, doped with MO and
DO2 (M for mono-valence cations, D for bi-valence cations), has been built from isothermal
sintering experiments. It has been compared with the one obtained in a previous study with the
same un-doped α-alumina raw powder. It seems that a transient liquid phase appears above a
critical temperature in the co-doped material during sintering. It is proposed that this transient liquid
phase is promoting densification and minimizing grain growth, as confirmed by transmission
electron microscopy (TEM).
Microstructure Evolution in Samples Prepared by Filter Pressing and Sintering of Zirconia Nanopowder
Authors: Zych Łukasz , Haberko Krzysztof
Published: March 2009

The aim of this work was the investigation of microstructure evolution during sintering of
zirconia nanopowder. The powder containing 97 mol. % ZrO2 and 3 mol. %Y2O3, with particle size
about 8 nm was prepared by the hydrothermal method. The flocculated and dispersed water
suspensions of the powder were filter pressed under 5 MPa, which led to green bodies of relative
density about 40%. Samples prepared from the suspensions showed distinct differences in
densification behaviour. The observation of the microstructure evolution (i.e. density, fracture
surface) in samples heat-treated at different temperatures, and detailed analysis of open porosity
evolution were performed.
Hot-Pressing and Hot-Forging of Polycrystalline Powder Particles with Unique Microstructures
Authors: Cannon W.R. , Petersson Anders , Auechalitanukuı Chira , Keshavan H. , Cuitino A.
Published: March 2009

The kinetics of hot pressing and the resulting microstructure of two types of
polycrystalline spherical powders (beads) were studied. The first were spherical ZrO2 beads
synthesized by sintering TOSOH spray dried ZrO2 powder loose in a crucible. The average bead
diameter was 51 μm and contained 0.3 μm grains. The second were Al2O3-ZrO2(1%Y2O3)
synthesized by plasma spraying spray dried powders into water to quench-in a partially amorphous,
partially nanocrystalline structure. The particle size was <25μm. Densification in both cases
depended on creep of the beads and densification rates at 1350°C were predicted well both by
equations from Helle et al.[1] for hot isostatic pressing and a finite element analysis method. The
microstructure of the Al2O3-ZrO2(1%Y2O3) was much more complex but densification kinetic also
followed the Helle et al.[1]equations if creep data from hot pressed specimens of the same powder
were substituted into the equations rather than literature values.
Sintering of Mechanically Activated Powders
Authors: Sreckovic Tatjana
Published: March 2009

Mechanical activation (MA) is used extensively as a relatively no expensive method for
the modification of physico-chemical properties of dispersed systems in technologies for obtaining
powders and ceramics. Different processes that occur during MA of powders lead to the formation
of specific structures that promote and accelerate solid-state reactions, as well as densification
during sintering. Changes of particle size and structure during MA of the ceramic parent material
are the sources of the morphological and structural metastability of the starting powders and they
can affect the sintering process, positively or negatively. Many properties of final polycrystalline
ceramics strongly depend on a green body microstructure and on conditions under which the green
body is sintered. From the other side green body microstructure depend on a powders
characteristics such as morphology, particle and pore size distributions. Regarding above mentioned
activation and sintering must therefore be carried out under strictly controlled conditions in order to
avoid influences that might cause a deterioration of the final properties of the ceramic materials.
The present study is focused on the processes of sintering that occurred in mechanically activated
single and multiphase oxide powders.
Pressureless Sintering of AIN
Authors: Fesenko Igor , Novikov Mykola , Kisly Pavlo
Published: March 2009

Pressureless sintering AlN ceramics of high density, high level of mechanical,
electrical and thermal properties, of predetermined level of microwave absorption was
achieved by the activation of the densification process as a result of simultaneous action of
high temperatures, developed surface of nanopowder particles, increased defects density and
fragmentation of nanopowder particles caused by the hydrodynamic treatment, action of
sintering aids in submicron-powder systems, as well as based on formation of grains with
high dislocation density and multilayer polytypes in nanopowder material, on
selfstrengthening of the material by plate-like grains, and besides based on altering the
dielectric properties of the materials via incorporating particles of high-melting-point metals
and metal-like refractories into the ceramic matrix. Optimal technological routes are
presented to manufacture either structural or functional components from ceramic AlN-based
materials. Material from AlN nanopowder is used in components operating in shock and
abrasive wear environment. Designed ceramic matrix composites with special thermal,
mechanical and dielectric properties based on submicron AlN powder are used in vacuum
microwave devices increasing mean power, widening the transmission band and enhancing
the effectiveness of amplifiers and oscillators.
Enhancement of Calcia Doped Ceria Nanoparticles Performance as UV Shielding Material
Authors: El-Toni Ahmed Mohamed , Yin Shu , Sato Tsugio
Published: March 2009

Calcia-doped ceria is of potential interest as an ultraviolet (UV) radiation blocking
material in personal care products because of its excellent UV light absorption property and low
catalytic ability for the oxidation of organic materials superior to undoped ceria. The performance of
calcia doped ceria needs more enhancement through further control of its oxidation catalytic activity
and improvement of its covering ability. In order to reduce the oxidation catalytic activity further,
calcia-doped ceria was coated with amorphous silica by means of seeded polymerization technique.
Generally, nanoparticles of calcia doped ceria do not provide a good coverage for human skin
because of the agglomeration of the nanoparticles. The platy particles are required to enhance the
covering ability of calcia doped ceria. This can be accomplished by synthesis of calcia-doped
ceria/plate-like material (e.g., potassium lithium titanate (K0.8Li0.27Ti1.73O4) and mica)
nanocomposite with subsequent silica coating. Calcia-doped ceria/plate-like material was prepared
by soft chemical method followed by silica coating via seeded polymerization technique. Silica
coated calcia-doped ceria/plate-like material nanocomposite was characterized by X-ray diffraction,
SEM, TEM, XPS and FT-IR.
Near-Net-Shape Ceramics by Reactive Processing
Authors: Snijkers Frans M.M. , Snel Marcel D. , Cooymans J.F.C. , Mullens Steven , Kodentsov A.A. , de With G. , Luyten Jan
Published: March 2009

Since conventional production of high-temperature materials involves high
investments and costly consumption of both energy and time, reaction engineering
methodology combined with near-net shaping is often the answer to problems associated
with the fabrication of advanced materials. Over the last decades, the number of different
reaction–based processing methods for near-net-shaped ceramics has gradually increased.
In this review, different reactive processing techniques and their potential for near-netshaping
are treated, e.g. SHTS (self-supporting high temperature synthesis), the Lanxide
method DIMEX®, reaction bonding (RB), reactive processing of Alumina-Aluminide Alloys
(3A) and Al2O3-Al alloyed metal composites (3AMC).
In addition to their potential for near-net shaping, other advantages to reactive processing
routes are recognized to be reduced processing temperatures, reduced glassy phase
formation at the grain boundaries, fine grained microstructures and improved mechanical
strength. Since the exothermic reactions constitute the base for reactive processing of high
quality materials in an economic way, control of these reactions is essential.
The process flows are described together with characteristic features of process and
materials. In addition, specific aspects of reaction-based synthesis will be illustrated with
examples from own work in the area of reaction bonding of silicon nitride and alumina.
Design of Nanohybrids from Well Defined NanoBuilding Blocks
Authors: Rozes L. , Fornasieri G. , Sanchez C.
Published: March 2009

Titanium-oxo clusters are employed as inorganic nanobuilding blocks in order to obtain
new organic-inorganic hybrid materials. Nanobuilding blocks are well-defined preformed entities
which allow a better control of the inorganic domains for the elaboration of hybrid nanocomposites.
The oxo-alcoxo cluster Ti16O16(OEt)32 presents a shell of labile ethoxy groups which can be
selectively exchanged with preservation of the oxo-core. Both the kinetics of the solvolysis and the
number of substituted titanium atoms are strongly dependent on the nature of the reactants. The
post-modification of the cluster lead to the elaboration of new oxo-alcoxo clusters Ti16O16(OEt)32-
x(OR)x (R : alkyl, phenyl… groups) and when polymerizable ligands, such as methacrylate or
styrenic ligands, are introduced at the surface of the nanobrick, new functional nanobuilding blocks
can be obtained. These functional clusters are then copolymerized with organic monomers leading
to 3D networks where the inorganic nano-fillers are covalently linked to the organic polymer and
act as very effective nano-cross-linker. These nanobricks can be considered as good models to
correlate the structure of hybrid materials and their physical properties especially their mechanical,
thermal, and optical properties.
Microwave Hybrid Sintering of Nanostructured YSZ Ceramics
Authors: Binner Jon , Vaidhyanathan Bala , Carney Tony
Published: March 2009

Radiant and hybrid sintering experiments have been performed on dry and wet processed
nanocrystalline 3-YSZ using both a conventional single stage and a new two stage sintering cycle.
Whilst densities >98.5% of theoretical were achievable by all combinations, a nanostructure could
only be retained using the two stage sintering approach. With hybrid heating the average grain sizes
for die pressed samples were in the range 70 – 80 nm whilst for the more homogeneous slip cast
samples a final average grain size of just 64 nm was achieved for a body with a final density of
>99%. It is believed that the primary advantage offered by hybrid heating is the ability to use a
much faster initial heating rate, 20 versus just 7oC min-1, without risking damage to the samples.
Whilst detailed characterisation of the properties of these nanostructured ceramics is still underway,
preliminary results have suggested that neither the hardness or toughness has been improved
compared to conventional, submicron-sized 3-YSZ. As a result of detailed crystallographic
characterisation this is believed to be due to a grain size dependent shift in the phase boundary
composition for nano YSZ ceramics leading to ‘over stabilisation’ at any given yttria content.
Equilibrium and Non Equilibrium Vaporization Processes of Ceramics
Authors: Heyrman Matthias , Chatillon Christian
Published: March 2009

In many elaboration furnaces, ceramics are used with other materials in vacuum
atmospheres. If temperatures are sufficiently high, vaporizations occur. Depending on the
thermodynamic stability of the investigated oxide, this vaporization can be congruent or not. In this
last case, chemical reactions with the ceramic can take place which can lead to the destruction of it.
One way to study these processes is the use of the High Temperature Mass Spectrometry (HTMS).
This technique allows determining the composition of the gas phase and the partial pressures of the
different gaseous species. By combining the spectrometer to a multiple Knudsen cell furnace, it is
also possible to determine activities by direct comparison of the partial pressures of each gaseous
species in equilibrium with a mixture and with pure components or compounds in the same
experiment.
Another recent development of the above technique is to characterize non equilibrium states by
determining evaporation and condensation coefficients. These coefficients describe the difference
between the real vaporization state of the system and the equilibrium state. To perform such
determinations it is necessary to vary the shape of the Knudsen cell orifices in order to change the
net evaporation process at the surface of the samples. Theses coefficients can be used to obtain
better modeling in processing.
Application of Fibrous TiO2 as a Photocatalyst in Aqueous Media
Authors: Tanaka Hidekazu , Higashio Ikuyo , Watanabe Keiichi , Suyama Yoko
Published: March 2009

Fibrous TiO2 with ca. 0.16 mm in width and 5 - 6 cm in length was prepared by drying a
suspension of monodispersed anatase particles at 363 K in air. The TiO2 fibers thus obtained were
thermally treated at the temperatures ranging from 363 to 1273 K for 1 h in air. Elevating the treating
temperature increases the crystallinity of anatase phase and reduces the specific surface area from 98
to 5 m2/g due to the sintering of particles. The rutile phase appears at 1273 K by transformation of
anatase phase. A photocatalytic activity of the fibers was examined by decomposition of methylene
blue (MB) in water under UV irradiation centered at 365 nm. The fibers decomposed the MB in
aqueous media under UV irradiation, indicating that the fibers possess a high photocatalytic activity.
The catalytic activity is considered to be enhanced on increasing the crystallinity of anatase phase,
nevertheless, that decreased with generation of rutile phase.
Mechanical Activation as a New Method for SHS
Authors: Bernard Frédéric , Paris Sébastien , Gaffet Eric
Published: March 2009

The use of mechanical activation (the elemental powder mixture is milled for a short time
at given frequency and impact energy) as a precursor to self-propagating high-temperature synthesis
(SHS) results in the formation of nanostructured porous materials. The mechanical activation step
was found necessary (i) to modify the thermal parameters of the combustion front (i.e. combustion
front velocity, thermal heating rate…) in the cases of Mo-Si, Fe-Al, Ni-Si (ii) to initiate a
combustion front in the case of systems having a low exothermicity. Nevertheless, the control of the
mechanically activated mixture characteristics and, the understanding of the mechanical activation
role on the SHS parameters are essential to produce end-products with expected microstructure.
Heat Transport in Superlattices and Nanocomposites for Thermoelectric Applications
Authors: Chen Gang
Published: March 2009

Energy transport in nanostructures differs significantly from macrostructures because of
classical and quantum size effects on energy carriers. Experimental results show that the thermal
conductivity values of nanostructures such as superlattices are significantly lower than that of their
bulk constituent materials. The reduction in thermal conductivity led to a large increase in the
thermoelectric figure of merit in several superlattice systems. Materials with a large thermoelectric
figure of merit can be used to develop efficient solid-state devices that convert waste heat into
electricity. Superlattices grown by thin-film deposition techniques, however, are not suitable for
large scale applications. Nanocomposites represent one approach that can lead to high
thermoelectric figure merit. This paper reviews the current understanding of thermal conductivity
reduction mechanisms in superlattices and presents theoretical studies on thermoelectric properties
in semiconducting nanocomposites, aiming at developing high efficiency thermoelectric energy
conversion materials.
Electric Field-Induced Unmixing in Mixed Ferrite Spinel (Co,Fe)3O4
Authors: Hong Jeong Oh , Yoo H.I.
Published: March 2009

Unmixing of a semiconducting ferrite spinel, (Co0.203Fe0.797)3O4 in an electric field was
examined at 1200oC in its disorder regimes of prevailing (cation) vacancies and interstitials,
respectively. It has been found that Co becomes enriched at the cathode in the interstitial-prevailing
regime and at the anode in the vacancy-prevailing regime, but to much smaller a degree than expected.
This confirms that the direction and degree of unmixing is governed by the difference in
electrochemical mobility of the competing cations, and the effective charges of the mobile cations are
appreciably reduced from their formal ones by the cross effect between the mobile ions and electrons.
Periodic Pattern Formation in Metal-Ceramic Reactions
Authors: Kodentsov A.A. , van Loo F.J.J.
Published: March 2009

Formation of diffusion zone morphologies periodic in time and space during metalceramic
reactions is considered as a manifestation of the Kirkendall effect. In a diffusion-controlled
interaction, the Kirkendall marker plane can bifurcate, which is attributed to diverging vacancies
fluxes in the reaction zone. When the Kirkendall plane is present in a phase layer, it attracts in situproduced
inclusions of “secondary-formed phase”, which, in turn, can result in a highly patterned
microstructure.
Growth and Characterization of (012)- and (001)-Oriented Epitaxial Anatase Thin Films
Authors: Lotnyk Andriy , Senz Stephan , Hesse Dietrich
Published: March 2009

Single phase TiO2 thin films of anatase structure have been prepared by reactive electron
beam evaporation. Epitaxial (012)- and (001)-oriented anatase films were successfully obtained on
(110)- and (100)-oriented SrTiO3 substrates, respectively. X-ray diffraction and cross section
transmission electron microscopy investigations revealed a good epitaxial quality of the anatase
films grown on the SrTiO3 substrates.
Diffusion and Defects in Oxides with the K2NiF4Structure Type
Authors: Skinner Stephen
Published: March 2009

K2NiF4 type oxides have received considerable attention in recent years as possible
mixed conducting membranes for technologically important applications such as solid
oxide fuel cells and oxygen generators. Much of this interest has focused on the
oxygen interstitial containing oxides such as La2NiO4+δ. This contribution will review
some of the recent work on these and related materials and will present new data on
the La2MO4+δ (M= Ni, Co or Mn) systems. In particular data on the oxide ion
diffusivity of these systems, as determined by oxygen isotopic exchange and SIMS
analysis highlighting the fast oxide ion diffusion (1 x 10-7 cm2s-1 at 750oC) present,
will be discussed and the significance of these data evaluated in relation to solid oxide
fuel cell systems. A further section of the presentation will consider the oxygen defect
species present and discuss the nature of the mobile oxygen ions. Finally some
preliminary data on the application of these materials as cathodes will be presented
and the performance of the cathodes on intermediate temperature electrolytes
discussed.
Electron Transport and Dielectric Breakdown Kinetics in Pr2O3 High K Films
Authors: Fiorenza Patrick , Lo Nigro Raffaella , Raineri Vito , Lombardo Salvatore , Toro Roberta G. , Malandrino Graziella , Fragalà Ignazio L.
Published: March 2009

Praseodymium based dielectric thin films have been deposited by Metal-Organic
Chemical Vapour Deposition (MOCVD). Special emphasis has been placed upon deposition
parameters crucial to obtain Pr2O3 phase and upon interfacial characterization. In addition, dielectric
properties have been correlated to structural and compositional characteristics of praseodymium
containing films.
The breakdown (BD) characteristics of Pr2O3 films have been investigated by an innovative and
handling approach based on C-AFM. Moreover, the BD kinetics have been elucidated considering
the role of defects in the conduction mechanisms.
Phase Transformations and Interstitial Atom Diffusion in Iron-Nitride, Iron-Carbonitride and Iron-Carbide Layers
Authors: Leineweber Andreas , Liapina Tatiana , Gressmann Thomas , Nikolussi Marc , Mittemeijer Eric Jan
Published: March 2009

α-Iron foils were exposed to various gas atmospheres containing all or a number of the components
NH3, CO, H2 and N2 for different periods of time at 550°C. In this way surficial compound layers were
generated which contain different iron nitrides (ε, γ’), iron carbonitride (ε) and/or iron carbide (cementite,
Fe3C). These compound layers were used to study phase transformations associated with N- and/or Cdiffusion
processes in the corresponding phases. These studies involved (a) the layer-growth kinetics of
cementite and (b) various solid-state phase transformations occurring in compound layers upon annealing in
vacuum.
Contribution to the Theory of Demixing of Yttrium in Yttria-Stabilized-Zirconia in an Electric Field
Authors: Belova Irina V. , Murch Graeme E. , Samuelis D. , Martin Manfred
Published: March 2009

In this paper, the nature of steady state demixing of yttria-stabilized
zirconia in an electric field is examined for the case of open system conditions (very
fine grain material) wherein the defects are everywhere close to internal surfaces
which allow the Schottky defect reaction to occur. It is shown that under such
conditions the applied force needs to be some 20 -25 times larger than for the case of
closed system conditions (Schottky defect reaction occurs only at the external
surfaces) in order to achieve the same degree of demixing of the cation components.
The effect of the constant electric field assumption as a substitute for the constant
current condition is also analyzed for a wide range of applied electric fields. It is
shown that in most cases, the assumption of a constant electric field provides only a
moderate correction to the shape of the concentration profile.