bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of Wastes-Based Extruded Ceramics Formulations
Authors: Raupp-Pereira F. , Ribeiro M.J. , Segadães Ana M. , Labrincha Joao A.
Published: March 2009

This work describes the studies carried out with various industrial wastes and natural byproducts
based on the SiO2-Al2O3-CaO system, aimed at extruding ceramic products of industrial
interest. Four waste materials were selected and characterised, namely, (i) Al-rich anodising sludge
(A-sludge), (ii) sludge from the filtration/clarification of potable water (W-sludge), (iii) sludge
generated in marble sawing processes (M-sludge), and (iv) foundry sand (F-sand).
Two different formulations were prepared and bodies were shaped by extrusion, after its detailed
optimisation. Screw extruded rods were then fired at several temperatures and characterised in
terms of relevant functional properties (shrinkage, density and mechanical strength). Their electrical
insulating properties were assessed by impedance spectroscopy.
The design of interesting technological properties, such as high electrical and mechanical resistance,
refractoriness, etc, was found to be easily achievable by controlling the initial batch formulation
and/or the sintering schedule.
Mineralizing Spinel Formation with Boron-Containing Compounds
Authors: Bhattacharya Goutam , Zhang Shao Wei , Jayaseelan Daniel Doni , Lee William Edward
Published: March 2009

Spinel (MgAl2O4) formation from stoichiometric MgO and Al2O3
is strongly mineralized by B-containing compounds such as boron oxide
(B2O3), lithium tetraborate (Li2B4O7) and sodium tetraborate (Na2B4O7) at
1000°C. TEM confirms that the mineralization with each compound
involves borate glass which is presumably formed on cooling from liquid at
1000°C. EDS shows the boron-containing liquids formed from B2O3 and
Na2B4O7-mineralized samples contain little alumina suggesting a templated
grain growth whereas those in Li2B4O7-mineralized samples dissolve
sufficient alumina to suggest dissolution-precipitation is occurring at this
temperature. XRD shows that Li2B4O7 is the most effective mineralizer
producing single- phase spinel with 3 wt% addition at 1000°C whereas B2O3
produces Mg3B2O6 at 1.5 wt% addition and both B2O3 and Na2B4O7-
mineralized samples show incomplete spinelisation which may be explained
by the composition of the liquids formed with these two mineralizers.
Refractory Materials and Products Based on Natural Wollastonite for Making Ceramic Accessories to be Used in Aluminium Industry
Authors: Vikulin V.V. , Rusin M. Yu. , Rusanova L.N.
Published: March 2009

A new technology has been developed for making refractory products based on the
naturally occurring wollastonite (calcium metasilicate) intended for the aluminum industry.
The application of natural wollastonite requires no hydrothermal treatment in an autoclave,
which considerably simplifies the manufacturing process and reduces its cost. A qualitative
comparative analysis of natural wollastonite from different mineral deposits was made to
choose an optimal modification with consideration for its availability. The articles were made
by using steel-mold pressing, slip casting and vacuum forming methods. For the development
of technology for manufacturing large-sized complex-shaped products the slip casting method
was used and the slip basic composition was determined comprising 80% of wollastonite as a
basic solid phase and 20% of plasticizers. The improvement in the thermal resistance of
wollastonite-based ceramics is assured by applying special techniques, namely by addition of
course-grained fillers. Thus, addition of about 15% of a course-grained fraction into the fine
wollastonite-based slip improves the thermal resistance of ceramics and affords 2-3 times
increase in their service life. The efficient way to increase the wollastonite-based ceramics
thermal resistance is addition of inorganic fibers. With the use of an inorganic fiber, the
materials have been produced with an apparent density ranging from 0.5 to 1.5 g/cm3 and an
ultimate compressive strength of 0.5 to 10 MPa. The study has been made into ceramics
structure comprising inorganic fibers. The developed materials are chemically inert to
aluminum melt. They show no sticking, no mechanical erosion and they are thermal-resistant.
With the above methods, the following products are being made on the basis of the naturally
occurring wollastonite: spouts, lining plates, heat nozzles, stopper-rod devices, pipes and other
articles that have been operating successfully in the aluminum industry of Russia.
Investigation into Hydration Resistance of CaO-Containing Materials
Authors: Lin Wei , Zhao Jian Li , Ommyoji Junji , Yamaguchi Akira
Published: March 2009

In order to develop an ideal material for the nozzle used in steel continuous casting
process, the hydration resistance of some CaO-containing complex oxides and CaO-NiO solid
solutions were investigated systematically. The hydration resistance of the complex oxides was CT
>CZ>CS>CF>CB3BTB2 B>CB2BS>>CB2BF>CB3BA>CAB2B>CaO. CT should be a promising material for the nozzle.
A large number of fine secondary-NiOss particles were separated from the CaOss crystal grains in
CaO-NiO solid solution and improved the hydration resistance.
YAG Powder Synthesis and Characteristics
Authors: Zarzecka-Napierała M. , Bućko Mirosław M. , Brzezińska-Miecznik J. , Haberko Krzysztof
Published: March 2009

Two techniques were applied to prepare single phase YAG powder: i) citrate process
based on complexing properties of citric acid with isopropyl alcohol additive as esterification agent
and ii) co-precipitation from relative nitrates solution with ammonia. At low temperature heat
treatment both techniques lead to the X-ray amorphous bodies. Their calcination at elevated
temperatures results in single-phase YAG powder. Differences in the behaviour of the amorphous
precursors during heat treatment will be shown.
Niobate Complex Perovskite Microwave Dieletric Ceramics Ba(Me1/3Nb2/3)O3 (Me= Zn, Co, Ni and Mg)
Authors: Azough F. , Leach Colin , Freer Robert
Published: March 2009

Ba(Me1/3Nb2/3)O3 (Me=Zn, Co, Ni and Mg) ceramics were prepared using the
conventional mixed oxide route; additives included Al2O3, Ga2O3, SiO2, WO3, B2O3 and V2O5.
Powders were mixed, milled for 18h, calcined at 1100°C, remilled pressed into pellets at 100 MPa,
sintered in air at temperatures in the range 1350-1550°C and then cooled at 360C h–1 to 5°C h–1.
Products were characterised in terms of phase analysis (X-ray diffraction), microstructure (SEM
and TEM) and electrical properties (relative permittivity, εr, dielectric Q value and temperature
coefficient of resonant frequency,τf). The Q values of the Ba(Me1/3Nb2/3)O3 ceramics depend on the
degree of cation ordering and the additives. Slow cooling leads to 1:2 ordering of the B sites and
enhanced dielectric Q values. For samples cooled at 5°C h–1 after sintering the Qxf values are in the
range 28000 to 98000 GHz, and are in the sequence Ba(Ni1/3Nb2/3)O3, Ba(Co1/3Nb2/3)O3,
Ba(Mg1/3Nb2/3)O3 and Ba(Zn1/3Nb2/3)O3. Additions of BaO-4WO3 or V2O5 yield higher Qxf values
than Al2O3. Highly ordered Ba(Zn1/3Nb2/3)O3 has a relative permittivity of 39.4, but most other
Ba(Me1/3Nb2/3)O3 ceramics exhibit εr of 31-32. The temperature coefficient of resonant frequency,
τf, varies from –18 ppm/°C (Ba(Ni1/3Nb2/3)O3) to +32 ppm/°C (Ba(Mg1/3Nb2/3)O3); the sintering
additives (Al2O3 and BaO-4WO3) change τf by typically 10-16 ppm/°C.
Giant Dielectric Response in Perovskite-Derivative CaCu3Ti4O12 Prepared by Polymerized Complex Method
Authors: Masingboon C. , Thongbai P. , Maensiri S.
Published: March 2009

Nano-sized powders of CaCu3Ti4O12 (crystallite size of 44, 58 and 71 nm) have been
synthesized by a polymerized complex method, followed by calcination the synthesized precursor at
600, 700 and 800°C in air for 8h. The CaCu3Ti4O12 powders were then characterized by XRD,
FTIR and SEM. Sintering of the powders was conducted in air at 1100°C for 16h. The XRD results
confirmed a typical perovskite CaCu3Ti4O12 structure in all the sintered ceramics, although the
presence of a second phase of CaTiO3 was observed in the sample sintered using the powders
calcined at 600°C. Microstructure of the sintered CaCu3Ti4O12 ceramics was observed by SEM and
the grain size of the materials evaluated with polished using the line intercept method were found to
be ~ 10-20 μm. A giant frequency-dependent dielectric constant samples (ε ~10000-60000) with
weakly temperature dependence and was observed in the all the samples. The highest dielectric
constant of the material was found to be ~60000 (at 140-160°C, 100 Hz) in the sample sintered
using the powders calcined at 700°C. The origin of the high permittivity observed in these
CaCu3Ti4O12 ceramics is attributed to the Maxwell-Wagner polarization mechanism.
Preparation and Characterization of Indium Tin Oxide for Optical Devices by Chemical Process
Authors: Itthivisit Patcharaporn , Kongtaweelert Samart , Traisak Sakda
Published: March 2009

Indium tin oxide (In-Sn-O, ITO) system is typical widely used as
transparent electrodes for display devices, transparent coatings for solar energy heat
mirrors and window films in p-n heterojunction solar cells because of their’s unique
properties of a high visible transparency, good electrical conductivity, and excellent
adhesion to the substrate, stable chemical property and easy patterning ability.
In this paper, preparation and characterization of Indium tin oxide (ITO) thin
films were studied by deposited dip coating process onto glass substrate. The mixing
of various molar ratio of indium chloride (InCl3) and tin chloride (SnCl2.2H2O),
(In:Sn mole ratio , 9:1, 7:3, 1:1), in acetylacetone were used as the starting solution.
The suitable In:Sn ratio for one stoichiometry indium tin oxide (In2Sn2O7) compound
were studied via hydrolysis process of mixed solution. The result of thermal
gravimetric analysis were used to supported and corrected of calcining temperature.
The precipitated powders were calcined at 500 0C and 600 0C. The result of XRD
spectrum indicated that the calcined 9:1 powders at 6000C was show the highest
stoichiometry of indium tin oxide (In2Sn2O7) compound with a polycrystalline cubic
structure. The ITO thin films were studied by deposited dip coating process onto glass
substrate with 20 layers at 600 0C for 1 hour. The optical properties, band gap energy
and microstructure of ITO thin films were investigated by UV-vis spectrophotometer
and Scaning Electron Microscope (SEM) respectively. The result of SEM was shown
highly homogeneous surface and average grain size 20 nm with 95% transmittance
which corresponding to XRD results. The calculated energy gap of ITO film was 3.40
eV.
Gate Materials and Fabrication-Processes of Metal-Ferroelectric-Insulator-Semiconductor Memory FETs with Long Data Retention
Authors: Sakai Shigeki
Published: March 2009

A recently-developed Pt/SrBi2Ta2O9/(HfO2)x(Al2O3)1-x /Si FET (x=0.75) shows outstanding data
retention characteristics. The drain current ratio between the on- and off-states is more than 2 x 106
after 12 days, and the decreasing rate of this ratio is so small that the extrapolated ratio after 10 years
is larger than 1 ×105. Among various materials researched for this decade, the combination of
SrBi2Ta2O9 and (HfO2)x(Al2O3)1-x or Hf-Al-O is regarded as the best choice presently. Device
performance by changing the Hf and Al composition ratio is investigated, and an Hf-rich-side region
around x = 0.75 is found most suitable. Pure HfO2 (x=1) is also a good candidate, but the gate leakage
current increase due to HfO2 crystallization is observed. Very recently, we fabricated a self-aligned
gate Pt/SrBi2Ta2O9/Hf-Al-O/Si FET, and measured the retention characteristics for 33.5 day that is
the longest period measured so far. This also shows a sufficiently large ratio of 2.4 × 105 after 33.5
day which will be 6.5 × 104 after 10 years by extrapolation. The development of a self-aligned gate
FeFET is an inevitable step of FeFET miniaturization according to the LSI scaling rule.
Fabrication, Microstructure and Mechanical Properties Relations of Ferroelectric Barium Titanate Reinforced with Alumina Micro/Nano Particulates
Authors: Jiansirisomboon Sukanda , Watcharapasorn Anucha , Tunkasiri Tawee
Published: March 2009

The effects of reinforced alumina particulates on some properties of ferroelectric barium
titanate ceramics were investigated. BaTiO3/xAl2O3 powders where x = 0, 3, 5, 10 and 15 mol%
were prepared by a solid-state mixed-oxide method. The starting alumina particle sizes used were
about 10 μm and 40 nm for the preparation of composite and nanocomposite ceramics, respectively.
Phase characterization by XRD suggested that the reaction between BaTiO3 and Al2O3 occurred
during sintering and resulted in BaAl2O4 and Ba4Ti10Al2O27 phases accompanying the main BaTiO3
phase. The densities of the ceramics were found to decrease with increasing content of Al2O3
dispersoid. Average grain size was also reduced with increasing amount of alumina addition. The
BaTiO3/Al2O3 nanocomposite ceramics at every composition contained smaller grains compared
with the normal composite ceramics which seemed to be the main governing factor that caused
higher hardness and lower fracture toughness in the nanocomposites.
New Advances in Forming Functional Ceramics for Micro Devices
Authors: Dorey R.A. , Rocks S. , Dauchy F. , Navarro A.
Published: March 2009

Micro electromechanical systems (MEMS) are finding uses in an increasing number of
diverse applications. Currently the fabrication techniques used to produce such MEMS devices are
primarily based on 2-D processing of thin films. The challenges faced by producing more complex
structures (e.g. high aspect ratio, spans, and multi-material structures) require the development of
new processing techniques.
Potential solutions to these challenges based on low temperature processing of functional ceramics,
selective chemical patterning, and micro-moulding are presented to show that it is possible to create
complex functional ceramic structures which incorporate non-ceramic conducting and support
structures. The capabilities of both techniques are compared and the relative advantages of each
explored.
Iterative Method in the Characterization of Piezoceramics of Industrial Interest
Authors: Pardo L. , Algueró Miguel , Brebøl K.
Published: March 2009

Although characterization of piezoceramics from resonance is a customary technique, the
works dealing with the determination of the ten elastic, dielectric and piezoelectric coefficients that
are needed in the full matrix characterization of such 6mm symmetry materials are rather scarce.
Even more, if the complex characterization is foreseen, thus accounting with the three types of
losses, few are the methods avaliable to obtain the material linear coefficients. This work deals with
such complex characterization by the use of Alemany et al. automatic iterative method. This
method has been applied to the four modes of resonance that are sufficient for the purpose: (1) the
length extensional mode of long rods, length poled, (2) the thickness extensional mode and (3) the
radial mode of a thin disk, thickness poled, and (4) the thickness shear mode of a thin plate. Recent
work of the authors has shown the limits in characterizing materials that arise from the use of the
Standard shear geometry and, therefore, and alternative geometry is used here.
This work presents the matrix characterization of some piezoceramics and the Finite Element
Analysis (FEA) simulation based on such characterization, of the samples used as a reliability
criteria of the results obtained by comparison of the experimental and simulated values at resonance
of the electrical parameters.
Sol-Gel Transparent PLZT Ferroelectric Ceramics
Authors: Płońska M. , Pisarski Wojciech A. , Pędzich Zbigniew , Surowiak Zygmunt
Published: March 2009

Lead lanthanum zirconate titanate (known as PLZT) ceramic powders have been prepared by
the modified sol – gel method, and underwent consolidation by the hot uniaxial pressing
method. Application of such technique of preparation permitted to receive fine-grained
transparent PLZT x/65/35 ceramics, with x = 8 -10 La at.%. The present publication gives a
detailed account of the relationships between technology and physical properties of obtained
materials. To analyze all ceramics SEM, EDS and mercury porosimetry were performed, and
dielectric properties were studied too. Quite wide light transparency from the visible to nearinfrared
range for PLZT ceramics was detected using optical absorption and infrared
spectroscopy.
Magnetoelectric Effect in Multiferroic Perovskite-Oxide Composites
Authors: Gomi Manabu , Ban K. , Nishimura Naoya , Yokota Takeshi
Published: March 2009

Magnetic, dielectric properties and magnetoelectric effect of ceramics with a composition
of 0.9 BaTiO3-0.1 LaMnO3 have been investigated. X-ray diffraction measurements showed that
the sintered ceramics are composites containing a small amount of (La, Ba)MnO3 phase in the
BaTiO3 matrix. These composites were multiferroic, having ferromagnetic and ferroelectric Curie
temperatures of 330 K and 392 K respectively. We found that the composite sintered at 1150 °C
exhibits a reduction of spontaneous magnetization as large as 55 % at room temperature when an
electric field of 1.4 KV/mm is applied. This reduction is probably ascribed to a change of hole
concentration distribution in the precipitated ferromagnetic (La, Ba)MnO3 and the resultant
decrease of ferromagnetic Curie temperature.
Ferromagnetic Homogeneous Polycrystalline Zn1-xCoxO Oxides
Authors: Zhang Yue Bin , Li Sean
Published: March 2009

In this work, the structural and magnetic properties of polycrystalline Zn1-xCoxO (x = 0,
0.02, 0.05, 0.0625, 0.10 and 0.15) oxides were studied in detail. Rietveld refinement of x-ray
diffraction spectra indicates that a single-phase wurtzite structure was formed in Zn1-xCoxO samples
for x up to 0.10. The magnetization for x = 0.02 can be fitted to a model with a paramagnetic Curie
term and a diamagnetic constant which could arise from spins of isolated free Co ions and a
diamagnetic background, respectively. For x > 0.02, however, an additional antiferromagnetic
Curie-Weiss term needs to employ for fitting. This is due to an additional contribution from
clustered Co ions that are in nearest neighbor positions through oxygen ions. Results show that the
substitution of Co at the Zn site does not occur in a completely random manner but Co ions appear
to have a tendency for clustering. In addition, the homogenous ZnO:Co thin film prepared by
Pulsed Laser Deposition on SiO2/Si substrate shows ferromagnetic behavior at room temperature.
Exchange Bias in CrO2/Cr2O3 Bilayer Thin Films
Authors: Srinath S. , Frey N.A. , Srikanth H. , Miao G.X. , Gupta A.
Published: March 2009

We have investigated the exchange bias in CVD grown epitaxial CrO2/Cr2O3 bilayer thin
films using hysteresis loops and resonant RF transverse susceptibility. M-H loops indicated an
enhanced coercivity without appreciable loop shift and the transverse susceptibility in CrO2/Cr2O3
bilayers revealed features associated with both the ferromagnetic and antiferromagnetic phases. In
addition, TS yielded large anisotropy constant (Keff) values depending on the fraction of Cr2O3
present. The large anisotropy fields observed cannot be accounted for by the variable thickness of
CrO2 alone and are indicative of possible exchange coupling between CrO2 and Cr2O3 phases that
significantly affects the effective magnetic anisotropy.
Compatibility Studies of Z- and Y-Type BaCo Hexaferrites for Low-Temperature Co-Firing with Ag
Authors: Lisjak Darja , Žnidaršić Andrej , Bregar Vladimir B. , Drofenik Miha
Published: March 2009

The trend for integrating and miniaturizing electronic devices requires the co-firing of
ferrites and Ag electrodes at 900°C. Here we report on compatibility studies using Z- and Y-type
BaCo hexaferrites, which are interesting for microwave applications. Samples with compositions
BaB3BCoB1.4BCuB0.6BFeB24BOB41 Band BaB2BCoB0.6BCuB1.4BFeB12BOB22 Bwere prepared with solid-state reactions at 1250°C
and 1000°C, respectively. For compatibility tests, samples with additions of 0-25 wt.% of Ag were
sintered at 900°C for 3h. The ceramics were characterized with X-ray powder diffraction and
electron microscopy combined with energy-dispersive analysis. When co-sintered with Ag the
hexaferrites decomposed to BaFeB12BOB19B and (Co,Cu)FeB2BOB4B or BaFeB2BOB4B. The incorporation of Ag in
the spinel phase was also detected. The degree of decomposition increased with the amount of Ag
and finally resulted in the complete disintegration of the samples with minimum 23 wt.% of Ag.
The influence of the observed phase-composition changes on the electromagnetic properties and
their dependence on frequency was evaluated.
Large Magnetoresistance at Oxide La0.7Ca0.3MnO3 and YBa2Cu3O7 Interfaces
Authors: Peña V. , Nemes N.M. , Garcia-Barriocanal J. , Sefrioui Z. , Leon C. , Te Velthuis S.G.E. , Hoffmann A. , Garcia-Hernandez Mar , Martinez J.L. , Santamaría J.
Published: March 2009

We report magnetoresistance in ferromagnet / superconductor / ferromagnet structures
made of La0.7Ca0.3MnO3 and YBa2Cu3O7 in the current in plane (CIP) geometry when the
temperature is fixed along the superconducting transition and the magnetic field is swept in an
hysteresis loop sequence. We describe experiments changing the geometry of current versus field.
We find that the shape and height of the magnetoresistance peaks is not modified no matter the
field is directed parallel or perpendicular to the current. This excludes interpretations in terms of
spontaneous vortices or anisotropic magnetoresistance of the ferromagnetic layers and supports
the view that the magnetoresistance phenomenon originates at the spin dependent transport of
quasiparticles transmitted from the ferromagnetic electrodes into the superconductor.
Structural, Magnetic and Transport Properties of Layered Cobaltites LnBaCo2O5+x
Authors: Conder Kazimierz , Stingaciu Marian , Pomjakushina Ekaterina , Podlesnyak Andrei
Published: March 2009

Structural and magnetic properties have been investigated for the series of layered
perovskite compounds LnBaCo2O5+x (Ln – rare earth metal) with different oxygen contents and
thermal treatment history. Transport properties were studied at applied magnetic fields on
TbBaCo2O5.5 single crystal grown by Travel Floating Zone Method (TSFZ). Oxygen isotope effect
on metal-insulator transition was investigated for compounds with different rare earth cations.
Fabrication and Characteristic Investigation of Multifunctional Oxide p-n Heterojunctions
Authors: Lu Hui Bin , Jin K.J. , Zhao Kun , Huang Y.H. , He Meng , Chen Zhi Hui , Zhou Y.L. , Yang G.Z.
Published: March 2009

A series of all-perovskite oxide p-n heterojunctions (PNHs) as well as perovskite oxide and
Si PNHs have been fabricated by a laser molecular-beam epitaxy. The good nonlinear and rectifying
I-V characteristics in the PNHs, unusual and high sensitivity of positive magnetoresistance in low
magnetic field in SrNbxTi1-xO3/La1-ySryMnO3 and La1-xSrxMnO3/Si PNHs, ps orders ultrafast
photoelectric effect in La1-xSrxMnO3/Si PNHs, as well as ferroelectric property due to the interface
enhancement in BaNb0.3Ti0.7O3/Si PNHs have been observed. It is expected that the further
investigation on the PNHs could not only stimulate theoretical study on the mechanisms but also
would open up new possibilities in the development and application of electrical devices.
Magnetophotonic Crystals: Now and Future
Authors: Inoue Mitsuteru , Uchida Hironaga , Lim P.B. , Baryshev Alex V. , Khanikaev A.V.
Published: March 2009

When the constitutive elements of photonic crystals (PCs) are magnetic, or even only a
defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and
magneto-optical properties. The strong photon confinement in the bulk of magnetic PCs results in
large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions,
such as the band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically
controllable photonic band structure, are predicted to occur theoretically. All the unique features of
the media arise from the existence of its magnetization, and hence they are called magnetophotonic
crystals providing the spin-dependent nature in PCs.
Processing and Characterization of Phosphorescent Strontium Aluminate Powders
Authors: Ow-Yang Cleva W. , Töral Gözde , Saraç Zehra , Gülgün Mehmet Ali
Published: March 2009

We have demonstrated the synthesis of lanthanide co-doped nominally SrAl2O4
powders that phosphoresce over long durations. Previous work has reported that the color of
phosphorescence depends on the nature of the alkaline earth cation, and that extended
phosphorescence in Eu2+ and other lanthanide co-doped MAl2O4 (M= Sr, Ca, Ba) systems
occurred with boron incorporation. To gain further insight into the mechanism of extended
phosphorescence persistence, we investigated the incorporation of other glass-forming
cations, Si and P. The Eu2+ and Dy3+ co-doped SrAl2O4 (SAED) powders were processed by
solution polymerization and annealed at 1000oC under a reducing atmosphere. X-ray
diffraction spectra revealed that these powders were multiphase. To characterize the optical
properties, photoluminescence spectra and phosphorescence persistence curves were
measured using a 325-nm wavelength excitation source. We report that the addition of B2O3
alone to SAED powders extended the persistence, while decreasing the luminosity, but more
interestingly, the addition of B2O3 along with other glass formers dramatically increased the
excitation luminosity.
Formation Mechanisms of Sol-Gel Derived Cordierite
Authors: Tkalcec E. , Ivankovic H. , Macan J. , Hriberski A.
Published: March 2009

Gels with cordierite stoichiometry, Mg2Al4Si5O18, were prepared by sol-gel technique using
three different starting aluminum sources: nano-sized γ-Al2O3, aluminium nitrate nonahydrate and
Al-sec-butoxide, as aluminum sources, using tetraetoxysilane (TEOS) and magnesium nitrate
hexahydrate in all three gels as sources for silicon and magnesium. The influence of Al-precursors
on formation mechanism and sintering behavior of gels was studied by differential scanning
calorimetry (DSC), X-ray diffraction (XRD) and dilatometry. Gels calcined at 700°C were
characterized by different specific surface area, pore sizes and different crystallization sequences.
For gel with nano-sized γ-Al2O3 α-cordierite was formed at 1220°C through intermediate MgAl2O4
phase. If aluminum was introduced as Al-sec-butoxide μ-cordierite crystallized in two steps (760
and 1070°C) and the transformation μ-cordierite→α-cordierite occurred at 1250°C. When
Al(NO3)3·9H2O was introduced as intermediate phase crystallized MgAl2O4 at ~870°C and μ-
cordierite at ~950°C. Both phases reacted with amorphous silica forming α-cordierite at ~1210°C.
Compacts prepared from gels with aluminum-nitrates and Al-sec-butoxide, respectively, sintered
between 700 and 1000°C, whereas the gel derived from γ-Al2O3 sintered in two steps; between 700-
1000°C and 1010 and 1250°C.
Equivalent Thermal Conductivity of Insulating Layer in Insulated Metal Substrates
Authors: Monden Kenji
Published: March 2009

An insulated metal substrate (IMS) is a circuit board comprising an insulating layer on a
metal base plate. The insulating layer is made from epoxy resin incorporating dense ceramic fillers.
The substrates are used in applications where electric parts generate intense heat. It is expected that
the insulating layer has higher thermal conductivity as the use of an IMS is expanded. Therefore, the
influence of percolation on the equivalent thermal conductivity (ETC) of an insulating layer is
considered. The Effect of the volume fraction of ceramic filler on the ETC of insulating layer in IMS
is investigated. The ETC as a function of volume fraction of filler is estimated. Based on these
experimental and numerical results, an ETC of a filler is evaluated. The ETC of an irregular filler is
presumed smaller than that of a spherical filler. It is thought that the control of filler size and shape is
important for the formation of high thermal conductivity of an insulating layer. In addition, an
improved equation for the ETC of IMS is proposed. The predictive values from the equation for an
improved IMS agree with experimental results.
Nanopowders Characterization Using the Optical Spectroscopy Methods
Authors: Popović Zoran V. , Dohčević-Mitrović Z. , Šćepanović M. , Grujić-Brojčin M.
Published: March 2009

The use of the optical spectroscopy techniques (Raman scattering, infrared reflectivity
and photoluminescence) in characterization of nanopowders is presented. These techniques, as
illustrated in the case of TiO2 and CeO2 nanopowders, offer the estimation of average grain size and
size distribution, strain effects, porosity and nonstoichiometry.
Freeze Casting of Ceramic Components Using Ice Cores and Ice Moulds
Authors: Moritz Tassilo , Richter Hans Jürgen
Published: March 2009

A novel shaping technique for advanced ceramic components is presented which allows
manufacturing of complex ceramic components with enclosed cavities by using ice moulds or
ice cores. Different suspensions of alumina and zirconia powders have been developed for
this special freeze casting technique. The suspensions must meet following requirements: high
solid content, the capability of flow, a freezing point between -10 and -2 °C, and a casting
temperature below 0 °C. After the casting process the moulds and cores could be easily
removed by sublimation. The suspension liquid was removed in the frozen state
simultaneously. In this way very complicated hollow or filled structures such as metallic or
ceramic components encapsulated in ceramic shells could be produced. No de-moulding was
necessary, no solid core must be removed, and no liquid phase appeared as known from other
lost-mould techniques. Ice mould casting is a very environmental-friendly shaping technique.
Furthermore, the influence of dispersing agents, anti-freeze agents and of the freezing speed
on the pore structure of the ceramic components has been investigated.
Freeze Casting of Aluminium Nitride
Authors: Wildhack S. , Aldinger Fritz
Published: March 2009

Aqueous freeze casting is an alternative wet shaping technique where water-based
ceramic suspensions containing a cryoprotectant are cast in molds, frozen and dried. The method
can be applied to various ceramic systems depending mainly on the ability to produce high solid
loading in aqueous ceramic slurries. Against this background, aqueous aluminum nitride (AlN)
suspensions were developed for the application in freeze casting.
The results show that the applied process additives are most effective not only in chemically
protecting AlN against hydrolysis but also in obtaining colloidally stable slurries with solid loadings
in excess of 50 vol.-%. After optimization of the viscosity, the freeze cast green samples exhibit
homogeneous microstructures without cracks and warpage. Besides, the systematic control of the
freezing step and the solid loading allow the preparation of sintered samples with defined density.
Twin-Screw Extrusion Modelling
Authors: McGuire P.A. , Blackburn S. , Holt E.M.
Published: March 2009

A mathematical model has been derived to describe the pressure drop along the
conveying and reverse sections of a partly full, fully intermeshing co-rotating twin-screw extruder.
The model extends previous work on single screw extrusion, whereby the Benbow-Bridgwater
model of paste rheology is combined with a force balance on a plug of paste.
Experiments to verify the model have been carried out using a laboratory scale twin-screw
extruder fitted with a hydraulic feeder and a modified barrel section allowing the collection of
pressure data at numerous points along the extruder. Initial results suggested that the model was
able to correctly predict the trends observed but underestimated the absolute values of the pressure.
This was attributed to a change in the rheology of the paste due to viscous heating effects. Further
experimental work was carried out to determine the relationship between the rheological parameters
and temperature; this allowed a temperature correction to be made to the initial data after which the
agreement with the predictions was greatly improved.
Roll Pressed LZSA Glass-Ceramics
Authors: Reitz G.M. , Montedo Oscar R.K. , Alarcon Orestes Estevam , Hotza Dachamir , Novaes de Oliveira A. P.
Published: March 2009

This work reports some experimental results regarding to a Li2O-ZrO2-SiO2-Al2O3 (LZSA) sintered
glass-ceramic material obtained by roll pressing of glass powders (mean particle size ≈ 5 μm) with
an added (7 wt.%) inorganic material (bentonite) as binder. The composition was characterized
using chemical analysis, laser-scattering particle size analysis, DTA, XRD, thermal expansion,
modulus of rupture (MOR) and deep abrasion (DA) measurements as well as density measurements
and SEM observations. From the results it was verified that the glass-ceramic materials obtained by
sintering and controlled crystallization, in the 850-1030°C temperature range, of glass powders,
have properties and characteristics decisively better than those of other traditionally used materials.
It is concluded that roll pressing technology is a potential candidate to produce sintered glassceramics
for many applications, such as, for example, large sheets panels for electrical and thermal
insulation.
Influence of the Additive Combination on the Aqueous Tape Casting of Barium Titanate
Authors: Friedrich Holger , Böse Holger
Published: March 2009

Two specifically determined dispersants and three binders have been investigated with respect to
their influence on the rheological flow behavior of aqueous BaTiO3 slurries for tape casting and the
properties of cast green tapes. Depending on the additive combinations, shear thinning and unique
Newtonian flow behaviors could be achieved. Hereby the respective flow behavior must be based
on specific additive interaction and determines the microstructural properties of the green tapes.
Thermodynamic Sintering and Microstructure of Nickel Ferrite Based Material
Authors: Condolf Cyril , Gabriel Armand , Pisch Alexander , Carry Claude
Published: March 2009

Sintering of nickel ferrite is strongly enhanced by carbonaceous debinding. It is
shown that this effect can be easily explained through thermodynamic consideration on
oxygen potential and content evolution during the sintering operation. DTG and dilatometry
experiment are in good agreement with driving force calculation and phase diagrams analysis.
New Polymeric Binders in Ceramic Processing
Authors: Szafran Mikolaj , Rokicki Gabriel
Published: March 2009

The results of studies on the application of new water-dispersible binders such as
poly(acrylic-styrene), poly(acrylic-allyl ether) for die and isostatic pressing and tape casting of
Al2O3 ceramics are presented. The properties of these acrylic polymers were modified by insertion
of selected amphiphilic macromonomers into the polymer chains. These amphiphilic
macromonomers, due to the proper ratio of the hydrophilic to hydrophobic fragments, play the role
of not only an internal plasticizer, but they also modify the adhesion of such binders to the ceramic
powder particles. The influence of chemical structure of these copolymers on the properties of
alumina ceramics is discussed. The investigations on properties of alumina ceramics obtained by
gelcasting method using new water soluble acrylic monomers containing hydroxyl groups in their
chemical structure as well as by direct coagulation casting method using polymeric flocculants are
also presented and discussed.
Phenomenological Theory of Sintering and its Application to Swelling
Authors: Kornyushin Yuri
Published: March 2009

The general phenomenological theory of sintering, formulated by the author in 1998 is
given. It is applied to the problem of swelling of materials under conditions of radiation. Driving
forces, caused by the presence of the evolution of heat in the volume of a sample (electric contact,
hf, inductive heating or penetrating radiation, e.g., neutrons could be the sources of the heat in the
bulk of a sample) are considered. The influence of these driving forces on sintering, structure and
properties is discussed. The role of mobile and immobile dislocations, grain boundaries, and pores
is regarded. Cycling and pulsing regimes of sintering are investigated.
Sintering of Tailored Powder Components: Multi-Scale Modeling and Experimentation
Authors: Olevsky Eugene
Published: March 2009

A true multi-scale approach is applied for the development of a new meso-macro
methodology for modeling of sintering. Sintering distortions of multi-layer and capillary-porous
composite powder structures are determined based upon the continuum theory of sintering
implemented in a finite-element code. The macroscopic constitutive parameters of the powder
material are obtained on the basis of the meso-scale simulations of a realistic grain-pore structure.
The model follows both the densification and the damage development during sintering using a
new fracture criterion for the prediction of macroscopic strength in sintering. The simulation
results are compared with the experimental data on sintering of zirconia, alumina, and Cu powder
composites. The modeling results contribute to the development of multi-layer powder metalceramic
technologies used for fabrication of components for thermal management of electronic
circuitry and wireless communication appliances.
Sintering of Solid Oxide Fuel Cell Materials
Authors: Nicholas Jason , De Jonghe Lutgard C. , Jacobson Craig P.
Published: March 2009

The synthesis of multilayer membranes for solid oxide fuel cells by means of co-firing
requires choice of compatible materials as well as a precise balance between densification rates of
the various layers throughout the densification process. One attractive practical objective is the
formation of dense electrolyte films on invariant, preformed electrode substrates, such as porous
electrodes of either ceramic or metal conductors. The formation of dense 10-20 micrometer thick
Ceria-based membranes on invariant substrates has been achieved by adjusting of the film sintering
properties trough selection of particle size, initial density, and novel sintering additives. The
accompanying theory pertaining to constrained sintering is examined, to determine the conditions
under which fully dense electrolyte layers can be produced on invariant or minimally variant
substrates.
Microstructure-Property Relationships in Sintered Alumina Ceramics
Authors: Galusek Dušan
Published: March 2009

The paper gives a brief overview of polycrystalline alumina ceramics, including the
solid-state sintered and ultrafine grained materials, and the liquid phase sintered aluminas.
The influence of glass-forming sintering additives of commercial interest (MgO, CaO, SiO2)
and processing conditions on microstructure development of polycrystalline alumina ceramics
are discussed in more detail. The influence of grain size, the presence and composition of
grain boundary glass, and of secondary crystalline phases in partially crystallized triple
pockets on stress state in alumina is discussed.
Influence of Microstructural Parameters on the Sintering of Transition Metal Carbides
Authors: Gosset Dominique , Dollé Mickaël , Legendre Fabrice , Guillard François
Published: March 2009

In the frame of the development of new nuclear reactors (Gen-IV project), materials able
to withstand very high temperatures are required. Among the components of the cores, the transition
metal carbides could be favourably considered as fission products barriers or inert matrix for the
fuel. They are highly refractory, have good neutron properties and fission products retention.
Unfortunately, first they are brittle and second the elaboration process of bulk materials requires
drastical conditions (temperature, pressure). We have then undertaken the comparison of different
materials to investigate the potentialities of nano-sized microstructures for the improvement of the
mechanical properties and to determine the impact of different elaboration routes to obtain high
density articles. The elaboration process of the nano-sized powders is presented elsewhere [M.
Dollé et al., this meeting]. Here, we compare different sintering processes (uniaxial hot-pressing,
spark plasma sintering) and we present a new process able to produce high density zirconium
carbide articles with soft conditions. We show that the sintering of co-ground zirconium and
graphite powders lead to high density, homogeneous, low grain-size materials at temperatures as
low as 1500°C. At the contrary, the nano-powders appear to be more difficult to densify that
classical micro-sized powders.
The Role of the Milling Step on the Sintering Behaviour of Monazite Powder LaPO4 - Densification and Resulting Microstructure
Authors: Bregiroux Damien , Audubert Fabienne , Bernache-Assollant Didier
Published: March 2009

Sintering behaviour of monazite powder was investigated as a function of the powder
milling conditions. To this aim, two techniques were used: attrition-milling and mixer-milling. We
show that it is of prime importance to control all the milling parameters in order to obtain controlled
microstructure and to avoid abnormal grain growth or residual large porosity.
Nanocrystals Synthesis by Microreactors
Authors: Nakamura Hiroyuki , Uehara Masato , Maeda Hideaki
Published: March 2009

A microreactor is a continuous flow reactor, which can control reaction conditions
precisely. We applied the microreactors to CdSe based nanocrystals synthesis and tuning particle
size, optical properties. Furthermore, homogeneous coating of ZnS and its coating amount tuning
was possible for optical properties improvement.
Synthesis and Characterization of Plate-Like Cerium Phosphate via Soft Solution Processing
Authors: Li Rui Xing , Yin Shu , Tang Qing , Sato Tsugio
Published: March 2009

Because of the low refractive indices, plate-like cerium phosphates (CePs) are expected to
be used as one of active ingredients in personal suncare cosmetics. Plate-like Ce2(PO4)2HPO4･H2O
particles were synthesized via solvothermal reactions of Ce(NH4)2(NO3)6 or Ce(SO4)2･4H2O in
phosphoric acid with or without nitric acid and sulfuric acid solutions. The variation of morphology
of Ce2(PO4)2HPO4･H2O particles significantly depended on the variety of cerium salt, isothermal
temperature and time, although all reaction products consisted of plate-like particles. This plate-like
compound showed excellent UV light absorption and transparency in the visible light region.
Consequently, it is suggested that the plate-like Ce2(PO4)2HPO4･H2O particles might be used as
suncare products to give an ideal optical effect of both UV-shielding ability and transparency in the
visible light region, as well as a good feeling on the skin.
The Instability of Li2O-Containing Celsian in BAS/Si3N4 Composites
Authors: Lee Kuo Tong , Huang Chin Bin , Aswath Pranesh B.
Published: March 2009

For application of high-temperature structural materials, in-situ Si3N4 reinforced BAS
composites have been explored. The main drawback for thermal cycling use is the persistent being
of hexacelsian BAS phase, which will cause a volume change around 300°C. The effective additives,
like Li2O can promote the polymorphic conversion of hexacelsian to celsian. The XRD experiments
show that in monolithic system the Li2O-containing celsian can persistent exist at 1650°C; however,
in BAS/Si3N4 composite it transforms into hexacelsian pahse at 1600°C. It is found that the
presence of Si3N4 could enhance the instability of the Li2O-containing celsian above 1590°C, in
which the hexacelsian is a stable phase in thermodynamics. The instability mechanism is indirectly
verified as the doping effect of Si, which is coming from thermal decomposition of Si3N4 in the
composites. It is well known that Si or SiO2 is a network former, which could make crankshaft-like
chain structure of celsian instable and enhance the layer structure of hexacelsian formed.
Synthesis and Photochemical Properties of White Calcia-Doped Ceria Nanoparticles via Soft Solution Processes
Authors: Sato Tsugio , El-Toni Ahmed Mohamed , Yin Shu , Li Rui Xing , Hidaka Hisao
Published: March 2009

White nanoparticles of calcia-doped ceria were prepared from the precipitate by reacting
CeCl3-CaCl2 mixed solution with NaOH solution at pH 12 and the oxidation with hydrogen peroxide
solution at 40oC, followed by the calcination at 700oC for 1 h. The sample before calcination
contained significant amount of OH- in the lattice and was yellow, but the powders calcined above
700oC were white, indicating that cationic defect formed by replacing O2- with OH- played as the
color center. Calcia-doped ceria particles were coated with amorphous silica by means of seeded
polymerization technique using hydrolysis of tetraethylorthosilicate (TEOS) or acid hydrolysis of
sodium silicate. The silica coating by seeded polymerization with TEOS was much more efficient for
the reduction of catalytic activity of ceria for the oxidation of organic materials than that by acid
hydrolysis of sodium silicate. It is confirmed that ceria particles caused far less damage to the DNA
plasmids upon UV illumination than either the titania or the zinc oxide reference pigments.
Structure of Yttrium Aluminium Garnet Obtained by the Glycothermal Method
Authors: Hosokawa Saburo , Tanaka Yusuke , Iwamoto Shinji , Inoue Masashi
Published: March 2009

The reaction of a stoichiometric mixture of aluminium isopropoxide and yttrium acetate in
1,4-butanediol (1,4-BG) at 300 °C directly yielded crystalline yttrium aluminium garnet (YAG),
while the reaction in ethylene glycol (EG) afforded an amorphous product in which a large amount of
EG moieties remained. The latter product exhibited an exothermic peak due to the crystallization of
YAG at around 900 °C and single-phase YAG was obtained by calcination at 1000 °C. The YAG
sample directly obatained in 1,4-BG had a large unit cell parameter (12.144 Å), whereas the YAG
sample obtained by the latter method had a unit cell parameter (12.015 Å) essentially identical with
the value (12.01 Å) reported in the JCPDS card. Rietveld analysis indicates that the former crystals
had Al vacancies at 24d sites and oxygen vacancies while the latter was essentially free from these
vacancies.
Synthesis of Hexagonal Ferrites by Citric Complex Method
Authors: Kikuchi Takeyuki , Nakamura Tatsuya , Miki Masamichi , Nakanishi Makoto , Fujii Tatsuo , Takada Jun , Ikeda Yasunori
Published: March 2009

Various hexagonal ferrites, which include hard and soft ferrites, were prepared by citric
complex method. High purity reagent of strontium carbonate, iron (III) nitrate ennnahydrate, cobalt
(II) nitrate hexahydrate and lanthanum oxide were used as starting materials. Prepared aqueous
solution was heated for dehydration and gelling. Thermal pyrolysis was carried out by heating the
gel. The obtained precursor powders were ground with an alumina mortar and compacted by
uniaxial pressing into disk specimens and then heated at temperature range between 1023K and
1523K in air. Phase identification and determination of lattice parameters were carried out by
powder X-ray diffraction. Scanning Electron Microscope was utilized to investigate the
microstructure of the polycrystalline ferrites. Magnetic properties were discussed by magnetization
measurements by using a vibration sample magnetometer. Magnetization and coercive force were
measured. In the case of M-type ferrite, M-type barium and strontium ferrites were formed at vary
low temperature relative to by conventional synthesis. The lanthanum and cobalt substituted M-type
strontium ferrite ultra fine powders prepared by citric complex method showed extremely large
coercive force.