bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of PbSe Nanocrystals by a Microchannel Reactor
Authors: Kim Jong Ung , Lee Jeong A , Ryu Beyong Hwan , Jun Ki Won , Kim In Ho , Choi Young Min
Published: March 2009

The synthesis of high-quality monodispersed nanocrystal is very important. Typical
synthetic method is rapid nucleation by injection of an organometallic precursor into a solvent
maintaining the reaction temperature. Since these methods are discontinuous processes, they are not
efficient for large-scale production of monodisperse nanocrystals. In this study, continuous
microchannel reaction technique is presented for synthesis of monodisperse lead selenide
nanocrystals in a diphenyl ether as high-temperature organic media. The microchannel reactor was
used due to its possibility of continuous process and reproducibility of narrow size distribution in
nanocrystal synthesis. The synthesis was carried out in microchannel reactor (800 μm diameter) made
from PTFE. Lead oleate and TOP-Se were used as organic precursor and diphenyl ether as
high-temperature organic solvents. Lead selenide particles with a size of less than 10nm could be
continuously prepared by this method. The nanocrystals have been characterized by X-ray diffraction,
TEM and optical absorption spectrometer.
Growth and Characterizations of Electrochemically Deposited ZnO Thin Films
Authors: Takashige Yumeji , Nebiki Takuya , Narusawa Tadashi
Published: March 2009

In this study,Wepresent ZnO thin films using electrochemical deposition method. ZnO
thin films are deposited onto metal(Cu) and semiconductor (n-type Si) substrates. The electrolyte
consists of a 0.1M Zn(NO3)2 solution, and we applied various potentials at different bath
temperatures. XRD shows preferential orientation to (002) that increases with the applied cathodic
potential and the bath temperature. Similar tendency is shown on both Cu and n-type Si substrates.
SEM micrographs show ZnO surface morphology is greatly affected by the applied cathodic
potentials. The RBS analysis reflects the rough morphology of ZnO thin film. The composition
ratio Zn:O on n-type Si substrate is determined to be 1.0:1.3 ± 0.3 at the cathodic potential of
-1.0[V] and the cell temperature of 70.
Effect of Heat Treatment on Compressive Properties of Open Cell Aluminum Foams
Authors: Li Chen , Wang Zhi Hua , Ma Hong Wei , Zhao Long Mao , Yang Gui Tong
Published: March 2009

This paper presents a study of heat treatment on the quasi-static and dynamic compressive
properties of the open cell aluminum alloy foams in as-fabricated (F), age-hardened (A) and
T6-strengthened (T6) conditions. Although the strain rate and heat treatment of foams are different,
all exhibit similar deformation behavior in the subsequent deformation. The yield stress of foams at
different strain rates are improved by heat treatment, all exhibit some strain rate sensitivity. However,
the densification strain of foams is not sensitive to heat treatment.
Observation of Dynamic Behavior in Primer-Coated Steel Welding by CO2 Laser
Authors: Kim Jong Do , Park Hyun Joon , Lee Mun Yong
Published: March 2009

This study examines for keyhole behavior by observing the laser-induced plasma and investigates the relation between keyhole behavior and formation of weld defect. Laser-induced plasma has been accompanied with the vaporizing pressure of zinc ejecting from keyhole to surface of primer coated plate. This dynamic behavior of plasma was very unstable and it was closely related to the unstable motion of keyhole during laser welding. As a result of observing the composition of porosity, much of Zn element was found from inner surface of it. But Zn was not found from the dimple structure fractured at the weld metal. therefore we can prove that the major cause of porosity is the vaporization of primer in lap position. Mechanism of porosity-formation is that the primer vaporized from the lap position accelerates dynamic behavior of the key hole and the bubble separated from the key hole is trapped in the solidification boundary and remains as porosity.
Identification of Precipitates Appearing in Al-Li-Cu-Zr Alloy
Authors: Park Tae Won
Published: March 2009

Identification of precipitates appearing during DSC scan of Al-2.1Li-2.9Cu-0.12Zr(wt. pct) alloy
has been conducted as a function of temperature by using a differential scanning calorimetry (DSC)
and transmission electron microscopy(TEM). In the as-quenched specimen from 540°C, three
couples of heat evolution and absorption peaks are observed during the heating period of DSC
experiments. It is found from TEM works that these peaks are associated with the formation and
dissolution of GP zone, δ‘, and T1(+θ') phases. The heat evolution peak appearing in the temperature
range over 36~78°C is due to the formation of GP zone. Heat absorption peak appearing in 78~140°C
is associated with the dissolution of GP zone. Heat evolution peaking at 166°C in the temperature
range over 140~190°C and next heat absorption peak are attributed to the formation and dissolution
of δ‘ phase. Heat evolution peaking at 288°C in the temperature range of 254~332°C and heat
absorption at high temperature are attributed to the formation and dissolution of T1(+θ'). The hump in
DSC curve at the temperature of 425°C is considered as the formation of hexagonal structure T2
phase.
Development of Environment-Friendly CaO Added AZ31 Mg Alloy
Authors: Lee Jin Kyu , Yoon Young Ok , Kim Shae K.
Published: March 2009

Molten Mg alloys burn rapidly in air if not protected. In order to handle molten Mg safely,
the molten metal should be protected from oxidation by covering the surface with flux or protective
gases. Sulfur hexafluoride (SF6) gas is widely used for Mg alloy as a cover gas and has proved to be a
successful inhibitor. However, the use of SF6 gas is limited because of its high cost and its significant
impact on global warming potential (GWP). Therefore, SF6 gas is being replaced by alternative
protection gases such as tetrafluoro ethane (HFC-134a) and 3M NovecTM 612. These gases are less
expensive and have lower GWP, compared with SF6 gas. Recent studies show that there has been
another attempt by adding CaO into Mg alloys to manufacture CaO added AZ31Mg alloy in terms of
increasing ignition temperature and reducing protective cover gas amount during melting and casting.
This paper discusses effect of CaO on ignition and oxidation behaviors of AZ31 Mg alloy as well as
on surface roughness and mechanical properties of AZ31 Mg alloy extruded bars.
Modification of V2O5-WO3/TiO2 Catalysts Supported on SiC Filter for NO Reduction at Low Temperature
Authors: Kim Youn Gae , Choi Joo Hong , Yu Liang , Bak Young Cheoul
Published: March 2009

The catalytic filter, a ceramic filter supported SCR catalyst, is a promising material for
treating particulates and NOX simultaneously. Recently, it is found that a SiC filter supported V2O5-
WO3-TiO2 [commercial catalyst system] shows a reasonable SCR activity around 320 °C [1]. In order to
improve its catalytic activity at low temperatures, the effects of Pt and MnOX addition on the catalytic
filter are investigated. The macro-porous TiO2 film was firstly coated on the pore surface of SiC filter
element using the solution composed of the preformed TiO2 particles (P25). Catalytic filters were
prepared by the impregnation of TiO2 coated-SiC filter in the solution containing the catalyst
components. The MnOX-added catalytic filter showed very wide temperature window from 150-340 °C,
providing NX slip concentration less than 20 ppm for the treatment of 700 ppm NO at a face velocity of
2 cm/s. Pt added-catalytic filter shifted the optimum working temperature towards the lower
temperatures (180-240 °C) compared to the one without Pt (280-330 °C). It is understood that MnOX in
the catalyst system roles as the main catalyst component while Pt rose as a electron modification
additive.
Photocatalytic Hydroxylation of Phenol over Ti-Containing Zeolites (TS-1, Ti-MCM-41)
Authors: Lee Gun Dae , Kim Sung Gab , Jeong Hee Hoon , Park Seong Soo , Hong Seong Soo
Published: March 2009

The photo-catalytic hydroxylation of phenol with hydrogen peroxide was carried out over
TS-1 and Ti-MCM-41 catalysts. For comparison, the dark (thermal)-catalytic hydroxylation of
phenol was also performed. The difference in catalytic behaviors of TS-1 and Ti-MCM-41 and
product distribution in both the reactions were investigated. The TS-1 and Ti-MCM-41 catalysts
having the Si/Ti ratio of 50 were prepared by in-situ crystallization and characterized using XRD,
UV-DRS. In the all reactions, the main products were catechol (CAT), hydroquinone (HQ) and
benzoquinone (BQ). In dark (thermal)-reaction, TS-1 showed a higher catalytic activity than Ti-
MCM-41. In photo-reaction, however, the activity of Ti-MCM-41 was comparable to that of TS-1.
The conversion of phenol and the selectivity to CAT in the photo-catalytic reaction were higher than
those in dark (thermal)-reaction. In the all reactions, the selectivity to CAT increased remarkably
when the selectivities to HQ and BQ decreased with reaction time.
Chiral (Salen) Complexes Encapsulated in Mesoporous ZSM-5 as an Optical Active Catalyst for Asymmetric Phenolic Ring Opening of Terminal Epoxides
Authors: Lee Kwang Yeon , Lee Young Hee , Shin Chang Kyo , Kim Geon Joong
Published: March 2009

ZSM-5 was modified by alkaline and acidic solution to introduce mesoporosity
in the crystals. Heterogenized Co(III) salen was prepared in the mesopores of ZSM-5 by
‘ship-in-a-bottle’ method. Phenolic ring opening of epoxides was performed successfully
by using encapsulated chiral salen catalysts. Very high enantioselectivity and conversion
were obtained in PKR reaction by immobilized catalysts.
Dislocation-Free Shallow Trench Isolation (STI) Chemical Mechanical Polishing (CMP) Process for Embedded Flash Memory
Authors: Kim Nam Hoon , Yoo Hae Young , Chang Eui Goo
Published: March 2009

The ambient and denuded trench top corner at the step of gate oxidation play an important
role to generate defect. Furthermore, dislocation-free flash process is proposed, and its mechanism as
well. The impact on dislocation of the other processes is also discussed. And we knew that using of
dry oxidation for gate oxide has the characteristic to reduce the dislocation. Consequently, the
dislocation free wafer is obtained by changing gate oxide from wet to dry in manufacturing embedded
flash.
A Study on Improved Characteristics of Electric Charge Storage after Thermal Treatment Using Teflon FEP Film
Authors: Kim Seong Jun , Kim Ji Kyun , Lee Hyeon Seok , Kwon Jeong Yeol , Lee Heon Yong
Published: March 2009

In this paper, we studied the method of electrets electrode which formed to accumulate
negative electric charge by corona discharge. The breakdown voltage sample and damaged sample by
various corona discharges have made material stabilization and improved characteristics of electric
charge storage throughout the annealing process. After the experiment made material stabilization
nearly melting point by many kinds of annealing conditions, we did the corona discharge again by the
charged high voltage, a discharge electrode gap, and a discharged time. As we compared it with the
best condition, we confirmed that characteristics of electric charge storage were improved.
Surface Acoustic Wave Device on (AlN/LGS) Substrate
Authors: Wu Sean , Lin Zhi Xun , Lee Maw Shung
Published: March 2009

Langasite (La3Ga5SiO14 or abbreviated as LGS) single crystal is an attractive substrate for
surface acoustic wave (SAW) devices requiring good temperature stability and higher
electromechanical coupling constant than quartz. AlN thin films are attractive materials that have
some excellent characteristics, such as high SAW velocity, piezoelectricity, high-temperature
stability, and stable chemical properties. In this study, AlN thin films were deposited on LGS to be a
new composite SAW substrate (AlN/LGS) by reactive RF magnetron sputtering method. SAW
delay-line device was manufactured on this substrate. The performance of the device was measured
by network analyzer (Agilent 8753E).The results exhibited the composite substrate (AlN/LGS)
increased the Rayleigh wave velocity, decreased the insertion loss of SAW devices, and suppressed
the harmonic response.
The Preparation of Fluorescent Nano Dye-Silica Particles by Sol-Gel Process
Authors: Na Young Joo , Park Sang Joon , Kim Ji Hyeon , Kim Jong Sung
Published: March 2009

The core-shell structure of dye-silica nanoparticle has been prepared. The dye-silica
nanoparticle can be used as a substitute of fluorescent dye for bio analysis. The hybrid organicinorganic
nanoparticle was prepared by sol-gel process using organic modified silane as the coupling
agent for flourescent dye and silica. The size of the particle was about 50 nm, which was measured by
DLS and confirmed by SEM photograph. The fluorescent dye (fluorescein-5-maleimide) was reacted
with (3-mercaptopropyl) trimethoxy silane to produce dye-silane compound, followed by the sol-gel
reaction with tetraethoxysilane(TEOS) and water to produce core-shell structure. The fluorescent
spectrum showed that the fluorescent intensity of dye-silica nanoparticle was higher than that of
fluorescent dye.
Effect of Catalyst on the Colloidal Silica Particle Growth in Direct Oxidation of Silicon
Authors: Lim Hyung Mi , Shin Hong Chul , Huh Soo Hyun , Lee Seung Ho
Published: March 2009

Nano size silica particles were produced by direct oxidation of silicon powder in the water
with the base catalysts. The average size of 10~100 nm was successfully prepared from the starting
material of silicon powder with variable procession parameters such as silicon solid content, choice of
catalyst and amount, the order of mixing, etc. The sodium hydroxide and ammonium hydroxide was
chosen for the base catalysts and their amount and addition order were found to control the size of
silica particles in the oxidation reaction. The limited amount of NH4OH as the first catalyst seemed to
limit the number of nucleus particles, and the limited amount of NaOH further feeded only for particle
growing rather than nucleus formation, thereby it was observed to be able to control the average size
of particles to be as large as 100 nm. The possible mechanism of particle growth was suggested by
solubility of silica and relative affinity of NH4
+ and Na+ ions to the surface of SiO2.
Effect of Ni Nano-Powders Addition on the Dielectric Properties of Ba(Ti,Zr)O3 Based Y5V Ceramics
Authors: Chen Lei , Wang Xiao Hui , Li Long Tu , Gui Zhi Lun
Published: March 2009

In this paper, the influence of nickel (Ni) nano-powders addition on the microstructures
and dielectric properties of Ba(Ti,Zr)O3 based Y5V non-reducing ceramics were investigated. The
X-ray diffraction (XRD) analysis indicated that the primary phase was Ba(Ti,Zr)O3 and no Ni phase
appeared until the amount of Ni exceeded 5mol%. Scanning electron microscope (SEM)
observation showed that the Ni particles distributed homogenously throughout BTZ ceramic matrix.
The incorporation of Ni altered the perovskite lattice parameters and thus led to the change of
polarization degree under electric field and the improvement of the dielectric constant at Curie
temperature.
Electric Field Induced Metal-Insulator Transition of Vanadium Dioxide Films on Sapphire Substrate Prepared by Inductively Coupled Plasma-Assisted Sputtering
Authors: Okimura Kunio , Nihei Yusuke , Sasakawa Yusuke
Published: March 2009

Single phase monoclinic vanadium dioxide (VO2) films were successfully grown on
sapphire (001) substrate by means of an inductively coupled plasma (ICP)-assisted sputtering with
an internal coil. In x-ray diffraction patterns, we observed reflections originating from monoclinic
VO2 with a main peak at 2θ = 39.77° corresponding to VO2 (020) for films on sapphire (001)
substrates. The VO2 films exhibited metal-insulater transition (MIT) at temperatures around 65°C
with three orders of change in resistivity. A simple device of VO2 film on sapphire (001) substrate
having aluminum electrodes as ohmic contacts with gap separation of 1.0 mm showed current
jump at an applied voltage of 48 V. The current jumped from 7 mA to 200 mA which was a limited
value of voltage source.
Dielectric Properties of Alumina Ceramics in the Microwave Frequency at High Temperature
Authors: Park Min Kyu , Kim Ha Neul , Baek Seung Su , Kang Eul Son , Baek Yong Kee , Kim Do Kyung
Published: March 2009

The dielectric properties of alumina ceramics have been measured using a free-space
time-domain technique from room temperature to 1400 oC in the frequency range 8.2 – 12.4 GHz. The
effects of thickness and lateral size of specimen were investigated with comparing the measured
values to the calculated ones based on the half-wavelength and the Gaussian beam focusing. From
these results the optimum specimen dimension for the high temperature dielectric measurement was
suggested with experimental verification.
Wear Characteristics of Binary Mg-Al, Si, Zn Alloys Coated by Plasma Electrolytic Oxidation Method
Authors: Song Byung Heum , Kim Ye Lim , Chang Si Young
Published: March 2009

Pure Mg, binary Mg-5.6wr%Al, Mg-1.0wt%Si and Mg-7.5wt%Zn alloys were coated by
plasma electrolytic oxidation (PEO) method, and their wear properties were investigated and
discussed based on surface roughness, thickness and component of coatings. All coatings showed
porous layer with some volcano top-like pores on the surface and the non-uniform thickness. The
coatings on Mg-Al, Mg-Si and Mg-Zn alloys were composed of primarily MgO and Al2O3, SiO2, ZnO,
respectively. The coating layer on Mg-Si alloy was thicker than that of Mg-Al and Mg-Zn alloys,
while it was less rough. The wear resistance of pure Mg and Mg alloys was improved by PEO method
and the coated Mg alloys showed better wear resistance compared to the coated pure Mg. In particular,
the coated Mg-Zn alloy revealed the best wear resistance, while the coated Mg-Si alloy had poor wear
resistance despite much thicker coating layer.
Effects of Deposition Parameters on the Crystallinities of CeO2 and Y2O3 Buffer Layers on Textured Ni Deposited by Magnetron Sputtering
Authors: Oh Yong Jun , Ra Jung Seok , Lee Ui Gil
Published: March 2009

The epitaxial growth conditions of CeO2 and Y2O3 single buffer layers on textured Ni tapes
were examined using rf magnetron sputtering, and the process conditions for the sequential and
mixture buffer layers of these two materials were investigated respectively in order to develop a more
simplified buffer architecture. The CeO2 single layer exhibited a well developed (200) epitaxial
growth at Ar/10%O2 gas below 450°C, although the epitaxial property was decreased with increasing
layer thickness. With regard to the deposition of Y2O3 on Ni, the epitaxial growth was not successful.
The epitaxy of Y2O3 on Ni was very sensitive to the O2 gas pressure during sputtering. The repeated
sequential architecture of the CeO2 and Y2O3 layers exhibited a good epitaxial property at
400°C/(Ar/10%O2) for the initial CeO2 layer and 700°C/Ar and 700°C/(Ar/10%O2) for the
subsequent Y2O3 and CeO2 layers, respectively. The Y-doped CeO2 buffers with (200) epitaxy were
successfully obtained by the co-sputtering of Ce and Y metals in a reactive gas condition, and the
maximum target Y/Ce ratio for the epitaxy was about 1/10.
Ceramic Electrode Materials for Electrostatic Chuck Applications
Authors: Choi Young Min , Kim Jong Ung , Ryu Beyong Hwan , Chang Hyun Ju , Kwak Chung Heop , Kim In Ho
Published: March 2009

In general, Electrostatic chuck (ESC) was used to fix and clamp the silicon wafer with
electrostatic force in the semiconductor fabrication process. Recently, due to their excellent chemical
and plasma stability and high thermal conductivity, sintered ceramics has been used as an insulator
material in the configuration of ESC. However, metals of high melting point, such as Mo, W, still
used for electrode materials. Because of the thermal mismatch between metal electrode and ceramic
insulator, micro cracks were produced at the interface during sintering process of ceramic or its
operation process with high temperature, which leads to reduce the life time of ESC. To improve the
compatibility between metal and ceramic, mesh type metal electrode was used in ESC but this type of
electrode results in inhomogeneous electrostatic force. Homogeneous clamping force is very
important to determine the final quality of semiconductor. We have investigated a ceramic
electrostatic chuck composed of conducting ceramic electrode of titanium nitride instead of metal
electrode. Aluminum nitride was added to titanium nitride to control the thermal expansion
coefficient. This composite electrode shows not only a good electrical conductivity but also an
excellent compatibility to dielectric layer. Compatibility between the electrode and dielectric layer
enable to design the electrode with continuous sheet type which leads to homogeneous electrostatic
force. Electrostatic force of ceramic ESC with conducting ceramic electrode was about 1700gf/4inch
wafer when the applied voltage was DC 3kV.
Temperature Dependence of Dominant Hillock Phases during Electromigration of Eutectic SnPb Solder Lines
Authors: Yoon Min Seung , Kim Oh Han , Joo Young Chang , Park Young Bae
Published: March 2009

In-situ observation by scanning electron microscope of the microstructure evolution near
the cathode depletion region and the quantitative analysis on the number of hillock phases in the
eutectic SnPb edge drift structure made it clear that the dominant migrating element and dominant
hillock phase were Sn and Pb, respectively, under 50 oC while both dominant migrating element and
dominant hillock phase were Pb above 100 oC. Such temperature-dependence of the dominant hillock
phases in the eutectic SnPb solder can be understood by considering the atomic size factors of the
metallic solid solutions.
Electrodeposition of CdS Nanostructures for Solar Cells Using Nano Imprint Templates
Authors: Kim Sung Jin , Kang Yoon Mook , Lee Heon , Kim Dong Hwan
Published: March 2009

We fabricated a CdS nano structures/CdS window layer/ ITO coated glass using
electrodeposition and nano imprinting technology (NIT). The CdS nano-structures were
electrodeposited using Na2S2O3 and CdSO4 electrolytes as the CdS sources and nano-imprint
templates. The x-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDS) results show
the electrodeposited CdS window layer and the secondary electron microscopy (SEM) analysis
showed the well aligned CdS nano-structure shape.
Interfacial Residual Stresses in Semiconductor Devices Measured on the Nano-Scale by Cathodoluminescence Piezospectroscopy
Authors: Pezzotti Giuseppe
Published: March 2009

Electron-stimulated (cathodo)luminescence spectroscopy is quantitatively used for
obtaining information about the residual stress fields piled up in semiconductor materials and
devices during manufacturing. This additional micromechanical output can be added to the
microscopic structural/chemical information available in the scanning electron microscope (SEM)
by other conventional techniques. Independent of the physical mechanisms behind the luminescence
emission, the spectral position of selected cathodoluminescence (CL) bands, observed in both
crystalline and glassy materials, is shown to possess high stress sensitivity and thus suitability as a
sensor for residual stress assessments. In this paper, we first quantitatively characterize the stress
dependence of typical CL bands observed in ceramic and glassy semiconductor materials. Then,
based on this knowledge, applications are shown of two-dimensional residual stress mapping on the
nano-meter scale in electronic devices involving atomically sharp interfaces, according to an
optimized automatic procedure performed into a field-emission gun (FEG-)SEM.
Electron Dose Rate Dependence of Phase Separation Induced by Electronic Excitation in GaSb Nanoparticles
Authors: Yasuda Hidehiro , Tanaka A. , Usui H. , Mori Hirotaro , Lee Jung Goo
Published: March 2009

The effect of electron dose rate on phase separation induced by electronic excitation in
GaSb nanoparticles has been studied in order to see whether a nonlinear relation between density of
excited states introduced and the efficiency of the phase separation is found or not. The phase
separation to two phases consisting of an antimony core and a gallium shell proceeds after
incubation time with increasing electron dose and does only at the dose rate above a threshold
value. It is suggested that such nonlinear behaviors take place as a cooperative phenomenon among
electronic-excitation effect, nano-size effect and temperature.
In Situ Synthesis of Hybrid-Reinforced Titanium Matrix Composites
Authors: Zhang Di , Yang Zhi Feng , Lu Wei Jie , Xu Dong
Published: March 2009

Novel hybrid TiB, TiC and rare earth oxide (Re2O3) reinforced titanium matrix composites were
in situ synthesized utilizing the reaction between Ti, B4C (or C), rare earth (Re) and B2O3 through
homogeneously melting in a non-consumable vacuum arc remelting furnace. In this work, Nd and Y
were chosen as rare earth (Re) added in the in situ reaction. The thermodynamics of in situ synthesis
reaction was studied. The results of X-ray diffraction (XRD) proved that no other phases appeared
except for TiB, TiC and Re2O3. The microstructures of the composites were examined by scanning
electron microscope (SEM) and backscattered scanning electron microscope (SEM). The results
showed that there were mainly three kinds of reinforcements: TiB whiskers, TiC particles and
Re2O3 particles. The reinforcements were fine and were homogeneously distributed in the matrix.
The interfaces of TiB-TiC and Nd2O3-Ti were examined by high-resolution transmission electron
microscopy (HREM).Transmission electron microscopy (TEM) and selected area diffraction (SAD)
were used to analyze the orientation relationships of TiB-TiC and Nd2O3-Ti. The orientation
relationship between TiB and TiC can be described as: [001] TiB //[001] TiC , (010) TiB //(110) TiC . The
orientation relationship of Nd2O3 and α-Ti can be described as: [110] Nd2O3 //[ 1213 ] Ti ,
(111) Nd2O3 //(1101) Ti , ( 001) Nd2O3 //( 2110 ) Ti .
Fabrication and Wettability Test of Silicon Nitrides with Ordered Protrusions
Authors: Kondo Naoki , Hyuga Hideki , Yoshida Katsumi , Kita Hideki
Published: March 2009

Silicon nitrides are often used as ladles, stalks, heater element protection tubes, etc., in the
metal casting industry. A low wettability for molten metals is required for these purposes since
wetting by molten metals leads to adhesion of solidified metals, which causes several problems.
Surface structure is known to affect wettability. Thus, the present study attempts to fabricate silicon
nitrides with controlled surface structures. Silicon nitrides, whose surfaces were covered with ordered
hemispherical protrusions, were fabricated by the slip-casting technique. The cast bodies were
sintered, and subjected to wettability tests using molten metals. For comparison, silicon nitrides with
as-sintered and polished surfaces were also prepared. The surface with protrusions exhibited a lower
contact angle compared to the as-sintered and polished surfaces. The contact angle depended on the
diameter of the hemisphere; it was the largest at a diameter of 0.3 mm.
Preparation of Tungsten Carbide/Stainless Steel Functionally Graded Materials by Pulsed Current Sintering
Authors: Kawakami Yuji , Tamai Fujio , Enjoji Takashi , Takashima Kazuki , Otsu Masaaki
Published: March 2009

In this investigation, functionally graded technique has been applied to prepare tungsten Carbide
alloys (WC-Co alloys)-austenitic stainless steel to improve corrosion and wear resistance and
reduce their fabrication costs. Two types of specimens were prepared by Pulsed Current Sintering
(PCS) method. One is fabricated from WC alloy (WC-20 wt% Co, WC-20 wt% Fe-46Ni) powder
and SUS316L stainless steel powder, and is designated “powder / powder process“. The other is
fabricated from pre-sintered WC alloy and SUS316L plate, and is designated “bulk / bulk process”.
Both types of specimens have four functionally graded layers. Mechanical properties of these
specimens were evaluated by three points bending test, and microscopy observations were made to
their microstructures. Although the proper bending strength of bulk / bulk process specimen was
obtained, the optimum sintering condition is sensitive to the sintering temperature and function
graded layers.
Development of Freeform Fabrication of Metals by Three Diminsional Micro-Welding
Authors: Horii T. , Ishikawa M. , Kirihara Soshu , Miyamoto Yoshinari , Yamanaka Nobu
Published: March 2009

A newly developed freeform fabrication process named 3D Micro-Welding, which is a
combined system of a micro-TIG welding and a layered manufacturing method, is demonstrated.
Various refractory alloys such as Inconel, stainless steel, and Invar can be freeformed besides
elemental metals like titanium. Small metal beads of ~1mm in diameter are formed by emitting
micro arc to the top of a thin metal wire of 0.2mm diameter. A fused bead is welded to a metal
substrate or previously formed beads. By continuing this process and building up beads layer by
layer under the control of CAD/CAM system, 3D objects were produced. In this study, optimization
of micro-welding parameters such as the waveform of pulsed arc current and electrode materials
were investigated and simple 3D objects of Inconel 600, SUS 304, Invar 42 were formed. The
interfaces between adjacent beads were joined well and no crack or pore existed in the formed
objects. The density and Vickers hardness of Inconel 600 objects showed comparable values to the
commercial Inconel alloy, however the yield strength and Young’s modulus was about 80% and
70% of that alloy, respectively.
Rust Layers Formed on Weathering Steels by Long-Term Atmospheric Exposure to Industrial and Coastal Environments
Authors: Asami Katsuhiko , Kikuchi M.
Published: March 2009

Rusts formed on several types of weathering steels and a plain carbon steel exposed to
environments for a long term were investigated by EPMA, XRD and TEM/ED. Information about
distribution of elements, type of rusts, depth distribution of rusts, and their relation with type of
steels and environments are made clear.
Corrosion Behavior of Pre-Treated Fe-Al Alloys in Aqueous Acid Solutions
Authors: Masahashi Naoya , Kimura G. , Oku M. , Hanada Shuji
Published: March 2009

The corrosion behavior of pre-treated Fe–Al alloy in a sulfuric acid solution and chloride-containing solution was studied. Alumina layer formed at 1073–1173 K on the surface of Fe–Al alloy improves the corrosion resistance of the alloy, whereas that at 1273 K does not improve it. This was explained by the defects of Al2O3 layer, the fraction of Al2O3 in the oxides, crystallity of Al2O3, and residual stress in the oxide layer. On the other hand, TiO2 layer produced by dip coating and subsequent annealing at 523–773 K slightly improved the corrosion resistance of the alloy. The effect of the oxide layer on the aqueous corrosion was discussed focusing on the quality of the oxide.
Laser-Arc Hybrid Welding
Authors: Katayama Seiji , Naito Yasuaki , Uchiumi Satoru , Mizutani Masami
Published: March 2009

Hybrid welding of stainless steels or aluminum alloys was performed using the heat
sources of YAG laser and TIG, or YAG laser and MIG, respectively. The effects of welding
conditions and melt flows on penetration depth, weld bead geometry and bubble/porosity formation
were investigated with X-ray transmission real-time observation method. A great effect of melt
flows on penetration depth and weld geometry was consequently confirmed. Concerning porosity
suppression in YAG-TIG hybrid welding of stainless steel, no bubble generation was attributed to
no porosity formation. On the other hand, it was revealed that the disappearance of bubbles from
the concave molten pool surface played an important role of no porosity in YAG laser-MIG hybrid
welding of aluminum alloys.
Hard a-Si3N4/MeNx Nanocomposite Coatings with High Thermal Stability and High Oxidation Resistance
Authors: Musil Jindřich , Zeman P.
Published: March 2009

This article reports on a new class of amorphous a-Si3N4/MeNx nanocomposite coatings
with a high (≥50 vol.%) content of Si3N4 phase; here Me=Zr, Ta, Mo and W. These nanocomposites
exhibit high (>1000°C) thermal stability against crystallization and high (>1000 °C) oxidation
resistance if the metal Me incorporated in the nanocomposite is correctly selected. It was found that
the Zr-Si-N film deposited on Si(100) substrate exhibits no increase of the mass (m=0) in
thermogravimetric measurements performed in flowing air up to 1300 °C, i.e. up to the temperature
that is the thermal limit for Si substrate but not for nanocomposite.
Control of Microstructure by Laser Spot Heating
Authors: Shibayanagi Toshiya , Tsukamoto Masahiro , Matsuda N. , Soga Y. , Abe Nobuyuki , Naka Masaaki
Published: March 2009

The present study tried to control grain structure in polycrystalline aluminum or titanium by means of a laser spot heating method as well as by a computer simulation technique. Monte Carlo simulation of spot heating was performed utilizing two-dimensional grain structure model composed of 200 x 200 sites with hexagonal cells. Grain growth proceeded preferentially in the higher temperature region and resulted in a large grain surrounded by small grains. This large grain tended to keep on growing during homogeneous heating after the spot heating, suggesting that the spot heating technique can fabricate a peculiar grain structure such as different grain size distribution and texture that are not realized by utilizing conventional uniform heating process. Laser spot heating utilizing a fiber-laser system realized heating of small area such as 30micorn diameter to bring about peculiar grain size distribution as calculated by the computer simulation.
Reverse Monte Carlo Modeling of Atomic Configuration for Amorphous Materials
Authors: Fukunaga Toshiharu , Itoh Keiji , Mori Kazuhiro , Sugiyama Masaaki
Published: March 2009

Reverse Monte Carlo (RMC) modeling, based on diffraction data, was applied to various kinds of amorphous materials to visualizing the three-dimensional atomic arrangement and to elucidate topological characteristics. For an as-grown amorphous carbon nanocoil, it could be clarified that graphene sheets are winding and the regular ABAB… stacking is lost and the configuration gradually changes to the hexagonal network with great regularity through heat treatment. Voronoi analysis of the RMC model could characterize the atomic configurations for NiZr2 and CuZr2 metallic glasses. The Zr environments are very similar in the two systems, but there are marked differences between the polyhedra around Ni and Cu atoms. The polyhedra around Ni atoms are dominated by prismatic-like polyhedra. In contrast, icosahedron-like polyhedra are preferred for Cu.
Experimental Determination fo Ga Activity in Liquid Ga-Sb-Tl Alloys by EMF Method
Authors: Katayama Iwao , Sendai Yusuke , Zivkovic Dragana , Manasijević Dragan , Zivkovic Zivan , Yamashita Hiromi
Published: March 2009

EMF of galvanic cell with zirconia –based solid electrolytes was measured to determine
the activity of Ga in liquid Ga-Sb-Tl alloys between 946 and 1233 K along the tree pseudobinary
lines of Ga-(Sb/Tl), (xSb/xTl = 1/3, 1/1 and 3/1) The cell used was:
Ga,Ga2O3|(ZrO2)0.92(Y2O3) 0.08|Ga-Sb-Tl, Ga2O3.
The activity of Ga (aGa ) was derived by :-3EF = RT ln aGa , where E is cell potential, F is Faraday’s
constant, R is gas constant and T is cell temperature. The activity of Ga shows slight negative
deviations from ideality in the section with positive deviation from ideality in the whole
composition range. The activity of gallium shows slight negative deviations from Raoult’s law in the
section with xSb/xTl = 3/1, moderately positive deviations in xSb/xTl =1/1 section and large positive
deviations in xSb/xTl =1/3 section.
The Effect of Yttrium and Indium Doping on the Structure and Electrical Properties of Zinc-Ferrite Nanoparticles
Authors: Maletin Marija , Moshopoulou Evagelia G. , Jankov Stevan , Rakic Srdjan , Srdic Vladimir V.
Published: March 2009

Yttrium- and indium-doped zinc-ferrite nanoparticles were prepared by a coprecipitation
method. The influence of doping level on the structure and the conductivity of the samples
obtained was investigated. It was found that Y-doped zinc-ferrite nanoparticles, with a single spinel
phase and a size of a few nanometers, are formed in the whole range of yttrium concentration.
However, In-doped zinc-ferrite nanoparticles were formed for all investigated indium
cooncentrations, but only the samples InxZn1-xFe2O4 with x.≤ 0.15 are single-phase (for x ≥ 0.20 a
second phase - cubic In(OH)3, is formed). The decrease and increase of the electrical conductivity
with yttrium and indium doping respectively are explained by taking into consideration the different
role of these ions in the spinel structure and the electron hopping mechanism.
Luminescence of Doped Nanoparticles of Wide Band Gap II-VI Compounds
Authors: Godlewski M. , Yatsunenko S. , Zalewska M. , Kłonkowski A. , Strachowski Tomas , Łojkowski Witold
Published: March 2009

Nanoparticles of wide band gap II-VI compounds doped with transition metal (TM) or rare earth (RE) ions are perspective phosphor materials and fluorescence labels for optoelectronic, biology and medical applications. The efficiency of 3d-3d and 4f-4f intra-shell transitions is shown to be enhanced in TM, RE doped nanoparticles. Two mechanisms of emission enhancement related to spin dependent interactions of free carriers with impurities are discussed. These interactions enhance the TM, RE intra-shell transitions by increasing the rate of host to impurity energy transfer. It is shown also that Al doping increases the intensity of light emission from ZnO nanoparticles.
Synthesis of Nano-Powder Materials Using Spray-Pyrolysis Method
Authors: Górnicka Barbara , Mazurek Bolesław , Mielcarek Witold , Prociów Krystyna , Warycha Joanna
Published: March 2009

In this work the laboratory–scale installation for synthesising powder materials with nano-size grains is presented. Nano-sized zinc and tin oxides were obtained using the spraypyrolysis (SP) method. The zinc oxide was derived from zinc acetate at 300oC, 430oC, 580 oC, 800oC and 950oC. The tin oxide was processed by the thermal decomposition of tin tartrate at 500oC. The SP synthesized zinc oxide was used for manufacturing a methane sensor which was characterized as possessing a much wider range of operating and substantially higher sensitivity, 10 times higher, to methane gas compared to a sensor made out of commercially available zinc oxide.
The Luminescence Properties of ZnO:Al Nanopowders Obtained by Sol-gel, Plasma and Vaporization-Condensation Methods
Authors: Grigorjeva Larisa , Millers Donats , Smits Krishjanis , Monty Claude J.A. , Kouam Jules , El Mir Lassad
Published: March 2009

ZnO nanocrystals were synthesized and characterized by XRD and SEM methods. The luminescence spectra and decay kinetics were studied under pulsed laser excitation (266 nm, 8 ns). ZnO and ZnO:Al powders were prepared by sol-gel and plasma chemical synthesis. These powders were used as a raw material for the SPVD (Solar Physical Vapour Deposition) process. In this way, the vaporisation-condensation phenomenon (VC) led to the formation of ZnO whiskers and nanopowders. The luminescence properties of the VC nanopowders were studied and compared to those displayed by the raw material. The Al dopant, present in the raw powders as a solid solution and ZnAl2O4 precipitates, was only present as Al ions in the nanopowders after the SPVD. The blue luminescence intensity increased considerably after SPVD. The whiskers type microstructures showed nonlinear blue luminescence dependent on the excitation pulse density.
Spectroscopic and Magnetic Properties of Gadolinium Macroacyclic and Macrobicyclic Complexes
Authors: Leniec G. , Kaczmarek Slawomir M. , Typek J. , Kołodziej Beata , Grech Eugeniusz , Schilf W.
Published: March 2009

As a result of the Schiff base condensation the gadolinium macroacyclic and
macrobicyclic Schiff base complexes have been synthesized and investigated by infrared
spectroscopy (IR) and electron paramagnetic resonance (EPR). Both electron ionization and
electron spray Molecular Spectroscopy spectra confirmed the [1:1] proportion of a ligand to metal
in gadolinium macrocyclic and mocrobicyclic Schiff base complex samples. The thermogravimetrydifferential
thermal analysis (TG-DTA) indicated the presence of two water molecules in the innersphere
of the macrobicyclic complex and confirmed no water coordination of the metal ion in the
macroacyclic complex. The temperature dependence of the integrated intensity of the EPR spectra
enabled the magnetic interactions in the spin system of these compounds to be revealed.
Temperature Dependence of the FMR Spectra of Polymer Composites with Nanocrystalline α-Fe/C Filler
Authors: Guskos N. , Maryniak M. , Typek J. , Pełech Iwona , Narkiewicz Urszula , Rosłaniec Zbigniew. , Kwiatkowska Magdalena
Published: March 2009

Two different concentrations of nanocrystalline material: α-Fe/C were prepared by the
carburization of nanocrystalline iron and characterized by XRD and SEM. The nanoparticles were
next used as fillers in polymer nanocomposites using the in situ polycondensation reaction in a
poly(ether-ester) matrix with two concentrations: 0.1 wt. % and 0.3 wt. %. The temperature
dependence of the ferromagnetic resonance (FMR) spectra was investigated to study magnetic
interactions in the compounds. The introduced FMR parameters (intensity and position of the right
peak) describe well the temperature dependence of FMR spectra of strongly interacting magnetic
nanoparticles. The FMR spectra depend strongly on the concentration of magnetic nanoparticles,
which influence the magnetic interactions between them. Two main critical points of the matrix
(the glass state and the freezing of benzene rings) influence the behaviour of the FMR spectra.
Revisiting Local Electric Fields on Close-Packed Metal Surfaces: Theory Versus Experiments
Authors: Kostrobiy P.P. , Markovych Bogdan M. , Suchorski Yuri
Published: March 2009

An external electrostatic field of the order of a few tens of a volt per nanometer causes significant changes in the electron density distribution near a metal surface. Because of differing electronic distributions and varying responses of electrons to the applied field for various metals, the resulting local field distribution in the close vicinity of the surface should depend on the electronic properties of the particular metal, even for flat surfaces. Field-free and field-modified electron density distributions for different metal surfaces were calculated using the functional integration method. This approach enables the exchange-correlation effects to be correctly considered and makes it possible to account for the proper field-effect for broad field ranges without using the perturbation theory. The results of calculations are compared with the field-ion microscopic observations.
Pt-Supported Nanocrystalline Ceria-Zirconia Doped with La, Pr or Gd: Factors Controlling Syngas Generation in Partial Oxidation/Autothermal Reforming of Methane or Oxygenates
Authors: Sadykov Vladislav , Mezentseva Natalya V. , Alikina G.M. , Lukashevich A.I. , Borchert Yulia V. , Kuznetsova Tatyana G. , Ivanov Vyacheslav P. , Trukhan Sergei N. , Paukshtis E.A. , Muzykantov V.S. , Kuznetsov V.L. , Rogov V.A. , Ross Julian R.H. , Kemnitz Erhard , Mirodatos C.
Published: March 2009

Nanocrystalline CeO2-ZrO2 (Ce:Zr 1:1) samples doped with La, Pr or Gd cations
(containing up to 30 at.%) were prepared via the Pechini route. Pt (1.4 wt.%) was supported via
impregnation with H2PtCl6 solution followed by drying and calcination. The samples’ surface
features were studied by SIMS and FTIRS of adsorbed CO. The oxygen mobility was characterized
by the dynamic oxygen isotope exchange and H2 TPR. Catalytic activity was studied in the flow
installation using diluted feeds (0.7% CH4 +0.5% O2 or 1% C3H6O + 0.5% O2 +0.5% H2O in He).
In the selective oxidation of methane (POM), the catalytic activity correlates with Pt dispersion
controlled by the oxidized sample’s ability to stabilize Pt2+ cations as precursors of small reactive Pt
clusters formed under reaction conditions. This is favoured by a larger doping cation (La) and a
developed network of nanodomain boundaries. At comparable Pt dispersion, the highest
performance was demonstrated by a La-doped system, which correlates with the highest
surface/near-surface oxygen mobility controlled by the strength of Ce-O bonds in the surface layer.
In the autothermal reforming of acetone, the activity trends differ from those in POM because of the
more prominent role of the oxygen mobility required to prevent surface coking.
Synthesis Improvement of Yb3+-Activated SnO2 Nanocrystals
Authors: Callone Emanuela , Carturan Giovanni , Jestin Yoann , Ferrari Maurizio
Published: March 2009

Yb3+ doped SnO2 nanocrystals were synthesized, using the hydrolytic route in the presence of starch as the size stabilizer. Starting from salt precursors, the nanopowders obtained with various Yb3+ loads are thermally stable up to 600 °C. They were characterized by XRD, solid state NMR, TEM, ICP and TG-MS techniques. The nanocrystal Cassiterite structure, with a size of a few nanometers (<6 nm), was identified by XRD, NMR and Raman measurements confirming a homogeneous dispersion of Yb3+ ions in the lattice. The preliminary assessment of the spectroscopic features of nanocrystals was performed by absorption and photoluminescence spectroscopy. The typical Yb3+ absorption peak, centred at 977 nm, and an intense 2F5/2→ 2F7/2 Yb3+ emission band were observed.
Optimization of Conditions of Preparation of YAG Nanopowders for Sintering of Translucent Ceramics
Authors: Chudoba Tadeusz , Teyssier Mathieu , Łojkowski Witold
Published: March 2009

The agglomeration of YAG (Yttrium-Aluminum Garnet Y3Al5O12) nanopowders doped with various rare earth ions obtained by the coprecipitation and calcination route is a major problem if it is wished to exploit the nano-size properties such as the transparency of dispersions of the powders or low temperature sintering. Investigations to optimize the preparation process of powders for High Pressure-Low temperature Sintering (HPLS) of semi-translucent pellets was undertaken. The appropriate milling time to decrease the agglomeration was evaluated with the help of ZETA- potential measurement. The dependence of the agglomerate size against the time of hand milling was used to optimize the process.
Ceria-Zirconia Nanoparticles Doped with La or Gd: Effect of the Doping Cation on the Real Structure
Authors: Sadykov Vladislav , Kriventsov Vladimir V. , Moroz Ella M. , Borchert Yulia V. , Zyuzin Dmitrii A. , Kol'ko Vera P. , Kuznetsova Tatyana G. , Ivanov Vyacheslav P. , Trukhan Sergei N. , Boronin Andrei I. , Pazhetnov Egor M. , Mezentseva Natalya V. , Burgina Elena B. , Ross Julian R.H.
Published: March 2009

The real structure of nanocrystalline CeO2-ZrO2 (Ce:Zr=1:1) systems prepared via the polymerized polyester precursor (Pechini) route and doped with La3+ or Gd3+ cations, up to 30 at.%, was studied by X-ray powder diffraction, EXAFS and Raman spectroscopy and the surface features characterized by XPS and SIMS. Undoped CeO2-ZrO2 system revealed nanoscale heterogeneity, perhaps due to the co-existence of Zr- or Ce-enriched domains. With large La3+ dopant the system remains bi-phasic within the studied ranges of composition, incorporation of the smaller Gd3+ cation stabilizes the single-phase solid solution. For both systems, the increase of dopant content was accompanied by a decline of domain size and an increase of the average lattice parameter of fluorite-like phases. Depletion of the surface layer by smaller Zr4+ cations was observed, while the surface content of a doping cation is either, close to that in the bulk (La) or below it (Gd). Such a spatial distribution of components results in some ordering of cations within the lattice. It is reflected in different modes of rearrangement of oxygen coordination polyhedra with the Gd or La content (distances and coordination numbers by EXAFS), and specificity of XRD patterns not conforming to a simple model with statistical distribution of oxygen vacancies.