bluuebunny/crossref_metadata_2025 huggingface dataset:
MEMS Assisted Fabrication of Cr Nanobowls
Authors: Di Di , Dong Pei Tao , Chen Jian , Chen Jiao , Wu Xue Zhong , Li Sheng Yi
Published: July 2011

Various bowl-shape nanostructures have attracted widely attention for their potential applications in novel optical, electronic and biomedical fields. With the assistance of MEMS standard process, we present an inexpensive and fast approach in this paper for the fabrication of 2-D interconnected networks of Cr nanobowls. Spin-coated monolayer silica-polymer hexagonal ordered colloidal crystal was used as starting templates to create polymer nanowells. Then metal deposition and calcination process helped to develop Cr nanobowls with polymer nanowells as templates. The 2-D nanostructures were characterized by field emission scanning electron microscopy (SEM). Our fabrication approach of nanobowls can be extended to a wide range of metal materials and substrates with controlled size and wall thickness.
Effect of Temperature on Elasticity of Silicon Nanowires
Authors: Wang Jing
Published: July 2011

A semi-continuum approach is developed for mechanical analysis of a silicon nanowire, which captures the atomistic physics and retains the efficiency of continuum models. By using the Keating model, the strain energy of the nanowire required in the semi-continuum approach is obtained. Young’s modulus of the silicon (001) nanowire along [100] direction is obtained by the developed semi-continuum approach. Young’s modulus decreases dramatically as the size of a silicon nanowire width and thickness scaling down, especially at several nanometers, which is different from its bulk counterpart. The semi-continuum approach is extended to perform a mechanical analysis of the silicon nanowire at finite temperature. Taking into account the variations of the lattice parameter and the bond length with the temperature, the strain energy of the system is computed by using Keating anharmonic model. The dependence of young’s modulus of the nanowire on temperature is predicted, and it exhibits a negative temperature coefficient.
Biocompatibility Study of Mn0.5Zn0.5Fe2O4 Magnetic Nanoparticles
Authors: Liu Jing , Zhang Jia , Wang Li , Li Yun Tao , Zhang Dong Sheng
Published: July 2011

To explore the preparation method of self-prepared Mn0.5Zn0.5Fe2O4magneticnanoparticles and were prepared employing a reduction co-precipitation method, transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (SEM-EDS)were used to characterize the product; The results indicated that the Mn0.5Zn0.5Fe2O4magneticnanoparticles were prepared successfully. EDS showed each Mn0.5Zn0.5Fe2O4magneticnanoparticles contained O, Mn, Zn and Fe elements. The result of heating test showed that Mn0.5Zn0.5Fe2O4can serve as a heating source upon AMF exposure leading the magneticnanoparticles to reach its phase transition temperature (41-47.5°C).To evaluate the biocompatibility of Mn0.5Zn0.5Fe2O4magnetic nanoparticles, which has the potential application in tumor hyperthermia.In the following study it will be used as drug and gene vector, so the compatibility of it should be examined. Then the use acute toxicity (by the mouse of LD50 test), micronucleus (MN) test and hemolysis test were presented to evaluate the toxicity of it in vivo . Its LD50 arrived at 7.1862 g/kg;Micronucleus test showed micronucleus rate of experiment groups had no significant difference compared with negative group. It has no hemolytic .
Fabrication and Characterization of Cobalt Nanostructure-Based Microelectrodes for Phosphate Detection
Authors: Bai Yin , Tong Jian Hua , Bian Chao , Xia Shan Hong
Published: July 2011

This paper presents the fabrication procedure and characterization of cobalt nanostructure-based microelectrodes for phosphate detection. Cobalt thin films with different plane, nano-scale structures were obtained on gold microelectrodes by adjusting the parameters of electrodepositing method. The result of the fabrication was examined by XRD and SEM, showing the crystal direction and surface morphology of the electrodeposited cobalt layer. Electrochemical characterization of these microelectrodes was performed. The electrodes deposited under different parameters present a linear response in the range from 10-6mol/L to 10-2mol/L with a slope ranging from -19 to -17.6mV/decade. The potential response becomes stable in 200s after the electrode was put into the phosphate solution. It could be assumed that the difference in surface morphology of the electrode caused by changing depositing parameters may have little affection to the response to phosphate.
Theoretic Study of the Structures and Electric Properties of N-Doped InSb Nanoclusters
Authors: Ding Jian Ning , Yuan Ning Yi , Wang Xiu Qin , Li Chang Lin , Ding Gu Qiao
Published: July 2011

The first-principle quantum mechanical method was used to investigate the structures and electric properties of N-doped. Doping of N atom to clusters is found to be energetically quite favorable except for n=16. Different from bulk material, the LUMO-HOMO energy gaps of the InnSbn(n=6-12,14,16,24) clusters are enlarged by doping of N. The analysis of the electron density of the HOMO and LUMO states was performed to understand the behavior .
Effect of Compressive Strain on Electrical Resistivity of Carbon Nanotube Cement-Based Composites
Authors: Luo Jian Lin , Duan Zhong Dong , Zhao Tie Jun , Li Qiu Yi
Published: July 2011

Multi-walled carbon nanotube (MWCNT) fiber reinforced cement-based composites (MWFRC) with 0.1 wt.% and 0.5 wt.% weight concentration of MWCNT (wcM)were prepared, associated with the reference. The electrical resistances and compressive strains of these cured nanocomposites under cyclic uploading/unloading were real-time collected, to explore their stress/strain-sensitive properties. Results reveal as follows, there is no self-sensing trait for the reference, but exists good piezoresisitivity and high strain sensitivity (above 110) for MWFRC; the fractional change in resistivity (Δρ) regularly descends or ascends following the compressive stress, or the longitudinal strain of MWFRC; the resistance caused by pore electrolyte polarization has obvious impact on the time-stability of the Δρ trendline of MWFRC with 0.1 wt.% wcM, similar to the reference, but negligible effect on that of MWFRC with 0.5 wt.% wcM.
Design and Fabrication of a Polymer-Based Micro Direct Methanol Fuel Cell
Authors: Wang Lu Wen , Tian Rui Xue , Leng Jia Xing , Zhang Yu Feng , Liu Xiao Wei , Zhou Zhi Ping
Published: July 2011

In this paper, a polymer-based micro direct methanol fuel cell (µDMFC) has been designed, fabricated and tested. Bipolar plates were manufactured with polydimethylsiloxane (PDMS) by molding method. Stainless steel plates with the thickness of 200μm were chosen to fabricate the current collectors. The 0.49cm2 5-layered MEA was fabricated by the catalyst coated membrane (CCM) method. Experiments revealed that the μDMFC generated a maximum power density of 8.30mW/cm2, when the μDMFC was supplied with 2M methanol solution at 0.1ml/min flow velocity under room temperature (20°C) and normal atmospheric pressure. And the cell behaved very steady operated in constant current mode for 7200 seconds (2 hours).
Application of KOH Anisotropic Etching in the Fabrication of MEMS Devices
Authors: Shang Zheng Guo , Wen Zhi Yu , Li Dong Ling , Wang Sheng Qiang
Published: July 2011

It is known that the wet chemical etching of silicon in alkaline solution has attracted wide attention due to its advantages such as lower cost, simpler setup, higher rate, smoother surface at micro level, higher degree of anisotropy, and lower pollution. In this paper, the key processes of fabricating vacuum microelectronic accelerometer and slits are presented. The cone curvature radius of the silicon tip arrays less than 30nm was fabricated with wet anisotropic etching of silicon in 33wt. % KOH solution at 70°C added potassium iodine (KI) and Iodine (I2) as additive and the cone aspect ratio was about 0.7. Smooth surface after etching in 33wt. %KOH solution added isopropyl alcohol (IPA) at 80°C was obtained and lateral etching was less than 5um after etching several hours for etching depth over 400um. Scalar slits with bottom width 25um and depth 500um were attained. A constant etch rate lead to precise and reproducible production. The test result reveals that the process to a specific occasion can reach practical requirements.
Micro-Stress Assembly of Fragile Miniature Parts
Authors: Wang Xiao Dong , Wang Lin , Zhang Xi Wen , Luo Yi , Liu Li Ping
Published: July 2011

Since miniature parts have the characteristics of small sizes, low strength and rigidity, and they are easily to be damaged during the process of assembly, a concept for micro-stress assembly was proposed. In order to achieve micro-stress assembly, an automatic assembly system based on machine vision and force feedback was developed. Finite element method was used to analyze the influencing factors causing assembly stress. In order to handle various kinds of parts, a new type of combined gripper was developed, furthermore, the gripper integrated with force feedback and a compliant structure can detect and control the manipulating force.
Design and Simulation of a Differential and Decoupled Micromachined Gyroscope
Authors: Liu Yang , Wang Ling Yun , Lei Ting Ping , Du Jiang , Jiang Yi Wen , Sun Dao Heng
Published: July 2011

In this paper, a differential and decoupled micromachined gyroscope fabricated by through-etching the silicon substrate anodically bonded on the glass substrate was presented. The decoupled structure can make the sense mode frequency match with the drive mode frequency and reduce the quadrature error. The sensitivity is further improved by differential detection using antiphase oscillation of double masses along the drive axis. Finite-element simulation is performed with ANSYS software to analyze the vibration mode. The device employs silicon-on-glass gyroscope sensor chip processed with Deep Reactive Ion Etching (DRIE) and glass-silicon anodic bonding. Then it is tested at atmospheric pressure. Drive mode and sense mode are obtained as 2015 Hz and 1957 Hz which are closed to the simulated ones. Q factor of the drive and sense mode also can be gained as 56 and 3.4.
Parametric Research on Micro-Zigzag Slot Mechanism in OICW
Authors: Liu Chuan Qin , Lou Wen Zhong , Zhang Long Fei , Lv Yong Jia
Published: July 2011

This paper describes the delayed effect on the motion characteristics of the slider in the S&A mechanism resulting from the micro-zigzag slot used in OICW (Objective Individual Combat Weapon) and studies its influence on the ability of filtering transient acceleration signals. Firstly, we established the mathematic model of the slider when the S&A mechanism was loaded by the rectangular pulse acceleration according to the Rigid Dynamic Mechanics Theory and got its analytical solution by using MATLAB. Secondly, to verify the feasibility of this micro-zigzag slot mechanism, we adopted two different kinds of acceleration loading curves, after the non-linear dynamic mechanics simulation on it by using ANSYS/LS-DYNA, displacement and velocity curves of the slider were calculated. Then, to find which structural parameter playing more important role in affecting the characteristics of micro-zigzag slot, we adopted Single-variable Method to study its structural parameter under the same simulation condition. The simulation results we got were almost consistent with the theoretical results. The parametric research of the micro-zigzag slot lays certain a foundation on the research of MEMS system.
Effects of Phosphorus-Doping on the Microstructures, Optical and Electric Properties in N-Type Si:H Thin Films
Authors: Ding Jian Ning , Ye Feng , Wang Shu Bo , Yuan Ning Yi
Published: July 2011

In this paper we present a system study of phosphorus-doped hydrogenated silicon (Si:H) films prepared on glass by plasma enhanced chemical vapor deposition (PECVD) technique with radio frequency (RF) (13.56 MHz) and DC bias stimulation. The films were characterized using Raman spectroscopy, X-ray diffraction (XRD), optical transmittance and square resistance measurement.
Optical Properties of Silicon Quantum Dots
Authors: Qiu Zheng Rong , Yu Hong
Published: July 2011

A first-principles study of the optical properties of silicon quantum dots (Si QDs) with different diameters is presented in this paper. Si QDs consisting of 10-220 Si atoms, the corresponding diameter ranges from 6-20 Å, with full termination of the Si interface with H are investigated in detail. The results show that both the band gap and the absorption spectrum of Si QDs are size-dependent. For Si QDs with diameter ranges from 6-20 Å, as the diameter decreases, the band gap increases, and a considerable blue-shift in the absorption spectrum is occurred. This unique property can be used to extend the absorption spectrum of the solar cell by mixing in QDs with different sizes. Therefore, the full spectrum of the sunlight may be utilized more efficiently.
Investigation on Silicon-Glass Electrostatic Bonding Time Experiment
Authors: Liu Xiao Wei , Tang Jia Lu , Chuai Rong Yan , Zhang Hai Feng , Wang Xi Lian
Published: July 2011

In this paper, we make a detail analysis of some factors, which affects the electrostatic bonding process. According to the electrical properties of glass, combined with the principle of electrostatic bonding, we analysed the relationship of critical bonding time, voltage and temperature as well as the factors which affect electrostatic bonding. Then we come up with the mathematical model of the intensity and temperature of electrostatic bonding. In accordance with the above-mentioned formula and the experimental data, we can get the following conclusions: the intensity of electrostatic bonding is much greater between 280°C to 370°C; the best temperature for this bonding is about 350°C; however, when the temperature is below 280°C,the intensity of electrostatic bonding is lower due to the great impact of particles under low temperature; but when the temperature is higher than 370°C,the mismatch of coefficient of thermal expansion of silicon and glass gets larger, then as a result, the intensity of this bonding has a significant decrease with the increasing of temperature.
Fabrication of Nano-Aperture Hollow Tip Array for Microplasma Etching
Authors: Xiang Wei Wei , Wen Li , Zhang Qiu Ping , Chu Jia Ru
Published: July 2011

In parallel microplasma etching system, microplasmas are generated in the hollow pyramidal tips array and extracted through the nano-apertures at the tips for maskless locally etching. In this paper, SiO2 hollow pyramidal tips array and nano-apertures of 50~200nm diameters at the tips are successfully fabricated using a low temperature nonuniform thermal oxidation and selective wet etching on a silicon wafer with high efficiency and low cost. Key issues such as the factors influencing the tip shape and quality, nonuniform oxidation phenomenon, releasing of hollow tips array with high width-thickness ratio (hollow pyramidal tip base width/sidewall thickness) and nano-aperture etching are presented and analyzed in detail. The results of this paper may lay a good foundation for ongoing experiments of parallel microplasma maskless etching.
A Capacitor-Free CMOS Low-Noise, Low-Dropout Regulator for Capacitive Micro-Machined Accelerometer Application
Authors: Lv Bing Jun , Wang Peng Fei , Liu Xiao Wei , Yin Liang , Xu Na
Published: July 2011

A capacitor-free CMOS low-noise, low-dropout (LDO) regulator for Micro-accelerometer is presented. Noise performance of the regulator is studied from a theoretical point of view and a chopper stabilized error amplifier is designed to minimize output noise. By adopting pole-zero frequency compensation technique, the proposed LDO regulator, which is independent of an off-chip capacitor, provides high closed-loop stability when the load current is switched by micro-accelerometer. The proposed LDO is designed and fabricated on a 2μm CMOS process. From the simulation results, it shows that the line regulation is 3.5mV/V and the load regulation is 0.33mV/mA when the load current changes from 0 to 30 mA. The experimental results show that the output noise of the regulator is less than 180nV/sqrt(Hz) at low frequency
Grain Size Effect in the Electrical Properties of Nanostructured Functional Oxides through Pressure Modification of the Spark Plasma Sintering Method
Authors: Quach D.V. , Kim S. , De Souza R.A. , Martin Manfred , Munir Z.A.
Published: July 2011

Through the use of a high-pressure modification of the spark plasma sintering method, it was possible to consolidate functional oxides (yttria- stabilized zirconia and doped ceria) to high densities and retain a grain size of < 20 nm. The role of the pressure on densification and on the grain size of the sintered samples was demonstrated. The pressure had a marked effect on density at relatively low temperature but an insignificant effect at relatively high temperature. It was found that when prepared with such small grain sizes, these oxides conduct protonically even at temperatures as low as room temperature. The dependence of the protonic conductivity is stronger dependence on grain size than what can be anticipated from a geometric consideration based on an increase in grain boundary area. This observation strongly suggests that factors other than an increase in grain boundary area play a role, a consideration that is being further investigated.
Sintering of Silicon Carbide Ceramics with Co-Addition of Gadrinium Oxide and Silica and their Mechanical Properties
Authors: Yano Toyohiko , Horie Yasutaka , Imai Masamitsu , Yoshida Katsumi
Published: July 2011

Effects of simultaneous addition of SiO2 and gadrinium oxide on densification of SiC ceramics were examined, and relation between microstructure and their mechanical properties were discussed. Total 11wt% of Gd2O3 and SiO2 were mixed with fine -SiC powder. The weight of Gd2O3 in (Gd2O3 + SiO2) were set as 0, 20, 40, 60, 80 and 100%. The mixture was hot-pressed at 1950oC under 40 MPa applied pressure for 1 h. In the case of 40Gd2O3 and 80Gd2O3 compositions, the effect of sintering temperature from 1900 to 2000oC was also examined. The bulk density increased with increasing Gd2O3 content at the sintering temperature of 1950oC. Bending strength of the sintered bodies also improved with increasing Gd2O3 content generally, but at 40Gd2O3 composition, the maximum over ~800 MPa was observed. Young’s modulous, Vickers hardness and fracture toughness also increased with increasing Gd2O3 content. The distribution of grain boundary phase was not homogeneous. Evaporation of additives, mainly SiO2, caused non-homogeneous distribution of grain boundary phase between outside and inside of sintered bodies. High temperature bending strength of 80Gd2O3 specimen was superior than that of 40Gd2O3 specimen.
Densification, Phases, Microstructures and Mechanical Properties of Liquid Phase-Sintered SiC
Authors: Hirata Yoshihiro , Matsunaga Naoki , Sameshima Soichiro
Published: July 2011

This paper reports the influence of sintering additives (RE2O3, Al2O3RE2O3, RE = Yb, Y and Gd, 13 vol%) and mixing effect of 30 nm SiC powder with 800 nm SiC powder on phases of grain boundaries, grain size of SiC, fracture toughness and strength of SiC hot-pressed at 1950°C under 39 MPa of applied pressure. Rare earth ions were uniformly adsorbed on negatively charged SiC particles with 150 nm Al2O3 particles in aqueous suspensions at pH 5. A rapid densification of SiC with one component RE2O3 occurred above 1700°C when a liquid of SiO2 (formed on SiC particles)RE2O3 system was formed. The Al2O3RE2O3 additives lowered a liquid formation temperature to 14001500°C and enhanced the densification rate of SiC. An increased solubility of 30 nm SiC in a liquid during dissolution-precipitation process provided an amorphous phase of SiCSiO2Al2O3RE2O3 system at grain boundaries and suppressed the grain growth of SiC. The fracture toughness of dense SiC was dominated by the grain boundary thickness controlled by grain size of SiC and amount of oxide additives. Mixing of 30 nm SiC with 800 nm SiC improved greatly the strength of SiC with two component oxides and the mean flexural strengths reached 740810 MPa.
WC/Ti Composite Material Enriched with CBN Particles Produced by Pulse Plasma Sintering (PPS)
Authors: Rosiński Marcin , Michalski Andrzej , Płocińska Magdalena , Szawłowski Jerzy
Published: July 2011

Tungsten carbide (WC) and WCCo powders added with 30 vol.% cubic boron nitride (cBN) and 5 and 12 wt% of Ti were sintered by the pulse plasma sintering (PPS) technique. The sintering process was conducted under a load of 75 MPa at a pressure of 5.10- 5 mbar and a temperature of 1100-1500°C for 5min. The phase composition, density, hardness and microstructure of the sintered material thus obtained were examined. In the cBN-WCTi5wt% composite with an addition of 6wt% Co, the cBN particles are well bound with the matrix. The transcrystalline fractures of the cBN particles also indicate that the binding forces between these particles and the WCCoTi matrix exceed the matrix cohesion. The interfaces between the cBN grains and the surrounding matrix are almost straight lines, and no reactions between the cBN grains and the matrix were revealed in SEM observations.
Fabrication of Transparent La2Zr2O7 by Reactive Spark Plasma Sintering
Authors: An Li Qiong , Ito Akihiko , Goto Takashi
Published: July 2011

Transparent La2Zr2O7 with cubic pyrochlore structure was first fabricated by reactive spark plasma sintering using commercially available La2O3 and ZrO2 powders. Single phase of pyrochlore La2Zr2O7 was obtained at a sintering temperature of 1673 K and sintering pressure at 100 MPa for 2.7 ks. The La2Zr2O7 sintered body had a uniform grain size of 1.5 m and exhibited 68% transmittance in the wavelength range of 4–6 m.
Preparation of α-Al2O3/TiN Multilayer Coating on Ti(C,N)-Based Cermet by Laser CVD
Authors: You Yu , Ito Akihiko , Tu Rong , Goto Takashi
Published: July 2011

α-Al2O3 and α-Al2O3/TiN multilayer films were prepared on Ti(C,N)-based cermet substrate by laser chemical vapor deposition.α-Al2O3 and NaCl-type TiN films were prepared at Tdep = 1148 K. α-Al2O3/TiN multilayer film showed dense structure of cross section, and its surface morphology consisted of aggregated spherical grains. The adhesion of α-Al2O3/TiN multilayer film prepared on Ti(C,N)-based cermet was higher as compared with α-Al2O3 film directly prepared on the cermet.
Fabrication of Silicon Nitride-Based Nano/Nano-Composite
Authors: Xu Xin , Zhang Jiang Wei , Nishimura Toshiyuki , Hirosaki Naoto
Published: July 2011

Silicon nitride/boron nitride nano/nano-composites were prepared by high energy ball milling and spark plasma sintering. The milling promoted the amorphization of starting powders with the presence of many homogeneous distributed nanocrystalline â-Si3N4 particles; most of the BN particles were transformed into nano-size and embedded in the amorphous phase. This, combined with low sintering temperature and rapid densification rate, leads to a uniform nano/nano composite microstructure. The nano-sized BN grains with an average diameter of about 10 nm were homogeneously dispersed in nano-sized (about 70 nm) Si3N4 grain boundaries. The obtained nano/nano composite shows high hardness, high strength, high superplasticity, good heat/corrosion resistance and good tribological properties.
Strengthening Mechanism of High-Strength Reaction-Sintered Silicon Carbide
Authors: Suyama Shoko , Itoh Yoshiyasu
Published: July 2011

A newly developed high-strength reaction-sintered silicon carbide (SiC), which has two or three times higher strength than conventional sintered SiC, is one of the most promising candidates for lightweight substrates of optical mirrors, because of its fully dense structure, small sintering shrinkage ( < 0.5 %), good shape capability, and low sintering temperature. In this paper, in order to improve the performance of the newly developed reaction-sintered SiC, the effect of the microstructure on the bending strength was investigated by focusing on a physical fracture model using observations from transmission electron microscopy and X-ray stress measurement. As a result, it was confirmed that the bending strength of the newly developed reaction-sintered SiC could be improved by reducing the size of residual silicon. The strengthening mechanism of the newly developed reaction-sintered SiC was assumed to be due to piled-up dislocations at the grain-boundary of residual silicon sites, based on Stroh’s fracture model of polycrystalline solids.
Effect of Annealing Atmosphere on Oxygen Diffusion through Ba-Fe-Based Perovskite Oxide
Authors: Watanabe Ken , Kida Tetsuya , Sakaguchi Isao , Ohashi Naoki , Shimanoe Kengo , Haneda Hajime
Published: July 2011

To determine the effect of the annealing atmosphere on oxygen diffusion through Ba0.95La0.05FeO3-dpellets,18O2tracer diffusion and high-resolution secondary ion mapping were performed. When annealing in air, the18O concentration around the surface up to a depth of 40 µm was almost constant. On the other hand, when annealing in vacuum, the18O concentration obviously decreased. High-resolution secondary ion mapping indicated that the18O concentration around the grain boundary was reduced. These results suggested that the grain boundary of BLF annealed in vacuum prevents oxygen diffusion.
Fabrication of Dye-Sensitized Solar Cells with Hydrothermally-Synthesized TiO2 Nanopowder Films
Authors: Nakamura Takahiro , Hayashi Kazuho , Ogihara Takashi
Published: July 2011

TiO2 nanopowders were synthesized hydrothermally from TiCl4 aqueous solution. Particle diameters could be varied in the range 5–65 nm by controlling the synthesis time and temperature. Dye-sensitized solar cells were fabricated using the powders and their power generation efficiencies were evaluated.
The Effect of Oxygen Vacancies on the Dielectric Responses of BaTiO3 Based Ceramics in the Ultra-Wide Frequency Range
Authors: Choi Youn Kyu , Hoshina Takuya , Takeda Hiroaki , Oh Jong Min , Tsurumi Takaaki
Published: July 2011

The effect of oxygen vacancies and their migrations on the dielectric responses of BaTiO3 (BT) ceramics and (Ba, Ca)(Ti, Zr)O3 (BCTZ) ceramics was studied using wideband dielectric spectroscopy. Both dipole and ionic polarization of BT ceramics after annealing in a reducing atmosphere markedly decreased. To elucidate the decrease of dipole and ionic polarization, we observed the domain width and the crystal structure of BT ceramics annealed in different PO2. The mass fractions of constituted phases in 90o domain were calculated using the refinement of XRD patterns to explain the degradation of ionic polarization by oxygen vacancies. From the results above, we judged that the decrease of dipole polarization was due to the domain wall clamping by oxygen vacancies, while that of ionic polarization was attributable to the lattice hardening by the incorporation of oxygen vacancies into the BT lattice. In the case of BCTZ ceramics, dipole polarization showed the same way as BT ceramics with annealing conditions but the ionic polarization was independent of PO2 in annealing because of anti-reducing behavior of BCTZ ceramics. On the basis of the effect of oxygen vacancy in BT ceramics and BCTZ ceramics, we could clarify the oxygen vacancy migration in BCTZ ceramics under high direct-current voltage (DCV).
Development of a Dye-Sensitized Solar Cell with a Carbon Counter Electrode Formed by Screen-Printing
Authors: Kakuda Tatsunori , Terasawa Takashi , Futakuchi Tomoaki
Published: July 2011

In this study, we attempted to develop a low-cost dye-sensitized solar cell (DSC) by substituting a screen-printed carbon electrode for the conventional platinum counter electrode. Carbon electrodes were formed from mixtures of activated carbon, carbon nanofiber, carbon black, and a resin. The best carbon electrode conversion efficiency obtained was approximately 90% that of a platinum-based electrode.
Growth of (111)-Oriented Epitaxial Bi(Mg0.5Ti0.5)O3 Films and their Characterization
Authors: Tanaka Hidenori , Yamada Tomoaki , Yasui Sintaro , Yamato Keisuke , WADA Satoshi , Funakubo Hiroshi
Published: July 2011

Crystal structure and electrical properties were investigated for Bi (Mg0.5Ti0.5)O3 films grown on (111)c- and (100)c-oriented SrRuO3//SrTiO3 substrates by pulsed laser deposition. Epitaxial films consisting of a single phase of perovskite were obtained on the (111) substrates. Additionally, the ferroelectricity was ascertained not only from the polarization - electric field hysteresis loops, but also from the piezoelectric response.
Fabrication of Lead-Free Semiconducting Ceramics Using BaTiO3-(Bi1/2Na1/2)TiO3 System by Sintering in Air Atmosphere
Authors: Tateishi Takashi , Joong Sang Han , Takeda Hiroaki , Hoshina Takuya , Kunej Spela , Tsurumi Takaaki
Published: July 2011

BaTiO3–(Bi1/2Na1/2)TiO3(abbreviated as BT-BNT) solid solution ceramics, as a lead-free PTC (Positive Temperature Coefficient of resistivity) thermistor material usable over 130°C, were synthesized in air atmosphere. By conventional processes, La-doping was not effective in giving semiconducting property to the BT-BNT ceramics because of volatilization of sodium and bismuth during sintering. By preventing the volatilization by lowering the sintering temperature using very fine TiO2powder and by adding calcium oxide to calcined BT-BNT powders, we obtained BT-BNT semiconducting ceramics which shows a resistivity change near Curie temperature.
Effect of Simultaneous Addition of Zr and Y on Electrical Characteristics of ZnO Varistors
Authors: Watanabe Takayuki , Fukumori Ai , Akiyamna Yuji , Sato Yuuki , Yoshikado Shinzo
Published: July 2011

The effect of simultaneously adding Zr and Y to Bi–Mn–Co–Sb–Si–Cr–Ni-added ZnO varistors (having the same composition as a commercial varistor) on the varistor voltage, leakage current, and resistance to electrical degradation were investigated. Varistor voltage increased with increasing amount of Y for addition of 0–2 mol % Zr. On the other hand, the nonlinear coefficient α prior to electrical degradation changed very little on the addition of both Y and Zr. With the addition of approximately 1 mol% Zr, the leakage current decreased with increasing amount of Y added. A ZnO varistor with a varistor voltage of approximately 600 V/m, a low leakage current, and excellent resistance to electrical degradation was fabricated by adding approximately 2 mol% Y and approximately 1 mol% Zr.
Molten Salt Synthesis of the Barium Strontium Titanate Ba1-XSrXTiO3 with KOH-KNO3
Authors: Kuze Takuya , Higuchi Masashi , Katayama Keiichi
Published: July 2011

The synthesis of Ba1-xSrxTiO3(BST) powders was attempted using KOH-KNO3 molten salt. The starting materials, Ba(NO3)2, Sr(NO3)2 ,TiO2,and the mixed salt of KOH-KNO3, were well-mixed. The mixture was heated at 300 to 500°C for 1 hour, and the product was thoroughly washed with de- ionized hot water. When the mixture containing excess TiO2 was used, single-phase BST powders with a particle size of 10~50nm were obtained.
Crystallization and Morphology of Glassy Sanbornite
Authors: Takahashi Yoshihiro , Ihara Rie , Fujiwara Takumi , Osada Minoru
Published: July 2011

We investigated the crystallization and resulting morphology of a stoichiometric barium-silicate glass 1BaO-2SiO2(glassy sanbornite) by using transmission electron microscope and Raman spectroscopy. A crystalline aggregate structure consisting of a Ba5Si8O21phase (trunk) and a β-BaSi2O5phase (branch) was observed in the heat-treated glassy sanbornite. The Ba-richer phase of Ba5Si8O21precipitated prior to the formation of the stoichiometric β-BaSi2O5phase, suggesting the presence of the region in which the Ba ions are enriched or cohesively distributed. A considerable structural similarity between the glassy sanbornite and the Ba5Si8O21phase was also suggested in this study.
Preparation of Barium Titanate/Strontium Titanate Multilayered Nanoparticles
Authors: Goto Takayuki , Nakashima Kouichi , Fujii Ichiro , Kuroiwa Yoshihiro , Makita Yoji , Wada Satoshi
Published: July 2011

Nucleation and particle growth conditions of barium titanate (BaTiO3, BT) were investigated for preparation of the BT/strontium titanate (SrTiO3, ST) multilayered nanoparticles. The conditions with and without BT nucleation were clarified. Epitaxial growth of the BT layer on the ST substrate particles was studied using both conditions. The formation of the BT layer on the ST substrate particles was confirmed using the condition with BT nucleation.
Preparation of Strontium Titanate Nanocubes Using Titanium Alkoxide and their Accumulations by Capillary Force
Authors: Iwatsuki Shogo , Kera Masatoshi , Nakashima Kouichi , Fujii Ichiro , Takei Takahiro , Kumada Nobuhiro , Wada Satoshi
Published: July 2011

Nanocubes accumulations were built up by meniscus method and developed to achieve a dense structure. For the first attempt, strontium titanate (SrTiO3, ST) nanocubes were selected for the nanocubes accumulations. The ST nanocubes were prepared by a solvothermal method. For Strontium titanate nanocubes, Sr(OH)2 and titanium isopropoxide (TP) were used as starting materials and were heated at 240°C for 18h in an autoclave. Size distribution of TP-derived ST nanocubes was narrower than TiO2-derived ST nanocubes. Moreover ST nanocubes accumulations were prepared by a meniscus method. A dense ST nanocubes accumulation of over 1 μm was prepared at an angle of 50 degrees at 60 °C. The crystal structures were determined by X-ray diffraction (XRD) and the microstructures were observed by scanning electron microscopy (SEM).
Fabrication of Artificial Superlattices Using Perovskite Nanosheets
Authors: Osada Minoru , Li Bao Wen , Sasaki Takayoshi
Published: July 2011

Bicolor perovskite superlattices (LaNb2O7)nL(Ca2Nb3O10)nC have been successfully fabricated by a layer-by-layer assembly using two different perovskite nanosheets (LaNb2O7 and Ca2Nb3O10) as a building block. The artificially fabricated (LaNb2O7)nL(Ca2Nb3O10)nC superlattices are structurally unique, which is not feasible to create in the bulk form.
Preparation and Dielectric Properties of Dense Barium Titanate Nanoparticle Accumulations by Electrophoresis Deposition Method
Authors: Wada Satoshi , Kondo Shuhei , Kita Tatsuya , Nakata Risa , Fujii Ichiro , Nakashima Koichi , Miyajima Naoya , Suzuki Tohru , Uchikoshi Tetsuro , Sakka Yoshio , Takei Takahiro , Kumada Nobuhiro
Published: July 2011

Dense barium titanate (BaTiO3, BT) nanoparticle accumulations were prepared by an electrophoresis deposition (EPD) method using three kinds of BT nanoparticles with different particles sizes and tetragonality. First, the BT particles were dispersed into ethanol using ball-milling technique, and an optimum milling condition was investigated. As the results, it was confirmed that ball-milling led to a formation of mixture between single-dispersed nanoparticles and aggregated particles. Thus, the aggregated particles in the slurry were removed by a centrifuge in order to obtain narrow the size distribution. Using well-dispersed slurry, BT nanoparticle accumulations were deposited on paradigm electrode by the EPD method. Despite various BT nanoparticles, the dense BT nanoparticle accumulations were obtained at relative densities of around 60 %. After gold electrode deposition on the both surfaces of the accumulations by spattering method, dielectric properties were measured at 20 °C, the highest dielectric constants of around 160 was measured at 10 MHz.
Preparation of Potassium Niobate–Barium Titanate Ceramics Using Well-Dispersed Nanoparticles and their Dielectric Properties
Authors: Yamashita Kenta , Shimizu Shigehito , Fujii Ichiro , Nakashima Kouichi , Kumada Nobuhiro , Tsukada Takeo , Wada Satoshi
Published: July 2011

ANbO3– BaTiO3(A=K, Na, or K0.5Na0.5) system ceramics were prepared using a conventional sintering method, and their dielectric properties were investigated. It was found that the dielectric constant of KNbO3-BaTiO3and (K0.5Na0.5) NbO3- BaTiO3system ceramics did not strongly depend on temperature between 20 and 400 °C, making them useful for capacitor application.
Piezoelectric Properties of Porous Potassium Niobate System Ceramics
Authors: Wada Satoshi , Mase Yasuo , Shimizu Shigehito , Maeda Kazuki , Fujii Ichiro , Nakashima Koichi , Pulpan Petr , Miyajima Naoya
Published: July 2011

Porous potassium niobate (KNbO3, KN) system ceramics were prepared by a conventional sintering method using carbon black (CB) nanoparticles. First, KN nanoparticles with a size of 100 nm was mixed with CB nanoparticles and binder using ball milling with ethanol. The mixture was dried, and pressed into pellets using uniaxial pressing. After binder burnout, these ceramics was sintered in air. Their piezoelectric properties were measured and discussed a relationship between porosity and piezoelectric properties. As the results, with increasing porosity, piezoelectric g33 constant increased significantly, which suggested that porous ceramics were effective for stress sensor application.
Piezoelectric Properties and Enhancement of Moisture-Resistance of K0.5Na0.5NbO3 by Adding ZnO-Based Glass
Authors: Oba Yoshinari , Kobayashi Ryosuke , Matsuo Yoshio
Published: July 2011

The ZnO based glass was added to calcined K0.5Na0.5NbO3 by ball milling for 20h. The addition of 1wt.% ZnO- based glass exhibited the following piezoelectric properties (kp=36%, Qm=236, e33T/e0=464). By increasing the amount of glass powder ~5wt.%, kp was decreased to 24%. However, Qm and e33T/e0 were observed slightly decreasing. Besides, the moisture-resistance of ZnO-based glass added K0.5Na0.5NbO3 was enhanced considerably as compared to that of K0.5Na0.5NbO3.
Ferroelectric Polarization Properties in High-Performance Bismuth Sodium Titanate Single Crystals
Authors: Suzuki Muneyasu , Kitanaka Yuuki , Noguchi Yuji , Akedo Jun , Miyayama Masaru
Published: July 2011

(Bi0.5Na0.5)TiO3 (BNT) single crystals were grown by flux method at a high oxygen pressure (Po2) of 1 MPa, and their polarization properties were investigated. BNT single crystals exhibited a saturated polarization hysteresis with a remanent polarizations (Pr) of 31 μC/cm2 along [100]c, 44 μC/cm2 along [110]c and 54 μC/cm2 along [111]c. These results show that spontaneous polarization of BNT is approximately 55 mC/cm2 or larger.
Microstructure Control of Barium Titanate Grain-Oriented Ceramics and their Piezoelectric Properties
Authors: Mori Rintaro , Fujii Ichiro , Hayashi Hiroshi , Nagamori Yoshitaka , Yamamoto Yuichi , Wada Satoshi
Published: July 2011

The Barium titanate (BaTiO3, BT) [110] grain-oriented ceramics along [110] direction were prepared by a templated grain growth (TGG) method. The [110] oriented BT platelike particles (t-BT) were used as template particles. The relationship between poling treatment program and piezoelectric constant was investigated. The change in the poling conditions did not greatly influence domain size and the piezoelectric constant. The relationship between piezoelectric properties and domain size in BT grain-oriented ceramics was investigated. The smaller domain size was required to increase the piezoelectric constant.
Single Phase Formation and Electric Properties of Bismuth Niobium Based Perovskite-Type Oxides
Authors: Shimamura Atsushi , Fujii Ichiro , Kumada Nobuhiro , Nakashima Kouichi , Azuma Masaki , Kuroiwa Yoshihiro , Kawada Shinichiro , Kimura Masahiko , Wada Satoshi
Published: July 2011

The structural, and dielectric and piezoelectric properties of (1-x)BaTiO3 – x Bi1/2K1/2(X1/3Nb2/3)O3(X=Cu, X=Mg or X=Zn) ceramic were studied. The single perovskite phase was observed when x≤0.5 for X=Cu and Mg and x≤0.2 for X=Zn. As x increased, the dielectric constant peak temperature and piezoelectric properties continuously decreased for X=Mg and Zn. On the other hand, those of X=Cu possessed a local maxima at x=0.7 and the peak temperature was 200°C and the large field piezoelectric constant,d33*, was 94 pC/N.
Microstructure Control of Barium Titanate – Potassium Niobate Solid Solution System Ceramics by MPB Engineering and their Piezoelectric Properties
Authors: Shimizu Shigehito , Kumada Nobuhiro , Nakashima Kouichi , Fujii Ichiro , Tanaka Daisuke , Furukawa Masahito , Kuroiwa Yoshihiro , Suzuki Tohru S. , Uchikoshi Tetsuo , Sakka Yoshio , Wada Satoshi
Published: July 2011

Effect of the microstructural homogeneity of 0.5 BaTiO3 - 0.5 KNbO3 (0.5BT-0.5KN) solid solution ceramics on the dielectric and piezoelectric properties was investigated. Microstructure of a sample prepared by a conventional sintering method was homogenous, and the room temperature crystal structure was assigned to cubic Pm3m symmetry and therefore the sample was paraelectric. On the other hand, microstructure of samples prepared by a two-step sintering method was inhomogeneous, that is, it was made of BT and KN grains. The large electric field piezoelectric constant d33* increased with increasing interface area.
High-Power Piezoelectric Characteristics of Sr2Bi4Ti5O18-Ca2Bi4Ti5O18-Based Ferroelectric Ceramics
Authors: Noumura Yoji , Sato Shigeki , Hiruma Yuji , Nagata Hajime , Takenaka Tadashi
Published: July 2011

The high-power piezoelectric characteristics of lead-free piezoelectric ceramics, based on a bismuth layer-structured ferroelectric, MnCO3-doped (Sr0.7Ca0.3)2Bi4Ti5O18(abbreviated as SCBT0.3 + Mnxwt%), were studied. SCBT0.3 + Mnxwt% lead-free ceramics showed an extremely high mechanical quality factor (Qm) of more than 3000 in the (33) vibration mode under small-amplitude vibration. The high-power piezoelectric characteristics of SCBT0.3 + Mnxwt% were measured using the high-power measurement method based on frequency sweep driving under a constant voltage condition. It was found that the vibration velocityv0-pof SCBT0.3 + Mn 0.2 wt% linearly increased up to approximately 3.0 m/s. Therefore, the Mn-doped SCBT0.3-based ceramics are a promising candidate for lead-free high-power applications.
Single Crystal Synthesis of Cubic Garnet Related-Type Li7La3Zr2O12 by a Self-Flux Method
Authors: Awaka Junji , Takashima Akira , Hayakawa Hiroshi , Kijima Norihito , Idemoto Yasushi , Akimoto Junji
Published: July 2011

We have successfully synthesized single-crystal samples of fast Li-ion conducting cubic Li7La3Zr2O12with the garnet related-type structure by a self-flux method using LiNO3at 1150°C. The as-grown Li7La3Zr2O12crystals are colorless and transparent; they also have a polyhedral-shape with a maximum dimension of 0.15 ´ 0.10 ´ 0.10 mm3. The powder XRD pattern shows the obtained crystals have cubic Li7La3Zr2O12structure, and the EDX analysis confirms the chemical composition of La : Zr = 3 : 2.
Saddle Point Energies from Ab Initio Jump Profiles in MC Simulation of Order Kinetics in Intermetallics.
Authors: Leitner Martin , Vogtenhuber Doris , Pfeiler Wolfgang , Püschl Wolfgang
Published: July 2011

Kinetic Monte Carlo (KMC) simulation is a valuable tool to investigate conﬁgu-ration changes in intermetallic compounds. The elementary process is the jump of an atomfrom a lattice site to a neighboring vacancy. In classical transition state theory the jump ratecontains the energy diﬀerence between the original equilibrium state and the saddle point (=transition) state. In traditional KMC the saddle point has mostly received rather careless treat-ment, setting it constant or relating it to the type of jumping atom. In the present work, saddlepoint heights were considered explicitly. Taking L12 ordered Ni3Al as an example, jump energyproﬁles for various atom environments were calculated ab initio in relaxed conﬁgurations ofa 3x3x3 supercell, employing the Nudged Elastic Band method where necessary. From theseresults, eﬀective ’pure’ saddle point heights were extracted. To show the eﬀect on kinetics,simulations of order-order transitions were done with jump probabilities based on these results.When compared to the old assumption of constant saddle point heights, both overall kineticsand detailed jump statistics result considerably changed.
Magic Numbers for Bimetallic Clusters
Authors: Braems Isabelle , Berthier Fabienne
Published: July 2011

An exact description of the distribution of 2D bimetallic clusters deposited on a square substrate has been obtained via an exact inventory algorithm. We show that several features of the monometallic distribution can be altered by the presence of a second species within the clusters. The diagram of ground-state morphologies of such clusters is built as a function of the chemical interactions between both components. As a consequence, the maxima in the cluster size distribution that indicate the magic numbers can be smoothened or shifted during co-deposition as a function of the composition of the two-component phase.
Special Microstructures and Twin Features in Ti50Ni50-X(Pd,Au)X at Small Hysteresis
Authors: Delville Remi , Shi Hui , James Richard D. , Schryvers Dominique
Published: July 2011

The breaking of symmetry due to atomic displacements in the austenite-martensite phase transformation generally leads to their crystallographic incompatibility. Energy minimizing accommodation mechanisms such as martensite twinning have been recently shown to be a source of hysteresis and irreversible plastic deformation. Compatibility between the two phases can however be achieved by carefully tuning lattice parameters through composition change. A dramatic drop in hysteresis and novel microstructures such as a lowering of the amount of twin lamella are then observed. Related theoretical and simulation works also support the existence of such microstructures including peculiar self-accommodating configurations at near-compatibility. We present the transmission electron microscopy (TEM) study of these novel microstructures for the alloy systems Ti50Ni50-xPdx and Ti50Ni50-xAux where the composition was systemically tuned to approach perfect compatibility. High resolution imaging of the interface between austenite and martensite supplies evidences of compatibility at the atomic level.
3D Phase Field Modeling of Martensitic Microstructure Evolution in Steels
Authors: Yeddu Hemantha Kumar , Ågren John , Borgenstam Annika
Published: July 2011

Complex martensitic microstructure evolution in steels generates enormous curiosity among the materials scientists and especially among the Phase Field (PF) modeling enthusiasts. In the present work PF Microelasticity theory proposed by A.G. Khachaturyan coupled with plasticity is applied for modeling the Martensitic Transformation (MT) by using Finite Element Method (FEM). PF simulations in 3D are performed by considering different cases of MT occurring in a clamped system, i.e. simulation domain with fixed boundaries, of (a) pure elastic material with dilatation (b) pure elastic material without dilatation (c) elastic perfectly plastic material with dilatation having (i) isotropic as well as (ii) anisotropic elastic properties. As input data for the simulations the thermodynamic parameters corresponding to Fe - 0.3% C alloy as well as the physical parameters corresponding to steels acquired from experimental results are considered. The results indicate that elastic strain energy, dilatation and plasticity affect MT whereas anisotropy affects the microstructure.
Helical Domain Patterns in Tube Configurations: Effect of Geometry Length Scales
Authors: Zhou R.H. , Sun Qing Ping
Published: July 2011

Superelastic NiTi polycrystalline tubes, when subjected to quasi-static stretching, transform from an initial austenite phase to a high-strain martensite phase by the formation and growth of a macroscopic self-organized helical domain as deformation progresses. This paper performed an experimental study on the effects of the externally applied stretching and tube geometry (length L, wall-thickness h and tube radius R) on the martensitic helical domains in the tubes under very slow (isothermal) stretching. The evolution of the helical domains with the applied strain in different tube geometries are quantified by in-situ optical measurement. We demonstrate that the shape of the self-organized helical domain and its evolution are governed by the competition between bending strain energy and domain front energy in minimizing the total energy of the tube system. The former favors a long slim helical domain, while the latter favors a short fat helical domain. The experimental results provide a strong support to the recently developed theoretical relationship.