bluuebunny/crossref_metadata_2025 huggingface dataset:
Behind the Quantum and Size Effects: Broken-Bond-Induced Local Strain and Skin-Depth Densified Quantum Trapping of Charge and Energy
Authors: Pan Li Kun , Gu Ming Xia , Ouyang Gang , Sun Chang Q.
Published: July 2010

Shrinking the size of a solid down to nanometer scale is indeed fascinating, which makes all the otherwise constant physical quantities to be tunable such as the Young’s modulus, dielectric constant, melting point, etc. The variation of size also generates novel properties that can hardly be seen in the bulk such as the conductor-insulator and nonmagnetic-magnetic transition of noble metals at the nanoscale. Although the physics of materials at the nanoscale has been extensively investigated, the laws governing the energetic and dynamic behavior of electrons at such a scale and their consequences on the tunable physical properties of nanostructures have not been well understood [C. Q. Sun, Prog Solid State Chem 35, 1-159 (2007); Prog Mater Sci 54, 179-307 (2009)]. The objective of the contribution is to update the recent progress in dealing with the coordination-resolved energetic and dynamic behavior of bonds in the low-dimensional systems with consideration of the joint effect of temperature and pressure. It is shown that the broken-bond-induced local strain and the associated charge and energy quantum trapping at the defect sites perturbs the atomic cohesive energy, electroaffinity, the Hamiltonian and the associated properties of entities ranging from point defects, surfaces, nanocavities and nanostructures. Application of the theories to observations has led to consistent understanding of the behavior of nanometer-sized materials and the interdependence of these entities as well as the means of determining the bond energy through the temperature-dependent measurements.
Size Effect on Thermal Properties in Low-Dimensional Materials
Authors: Zhao Ming , Jiang Qing
Published: July 2010

An extension of the classical thermodynamics to nanometer scale has been conducted to elucidate information regarding size dependence of phase transition functions and binary phase diagrams. The theoretical basis of the extension is Lindemann′s criterion for solid melting, Mott′s expression for vibrational melting entropy, and Shi′s model for size dependent melting temperature. These models are combined into a unified one without adjustable parameters for melting temperatures of nanocrystals. It is shown that the melting temperature of nanocrystals may drop or rise depending on interface conditions and dimensions. The model has been extended and applied to size dependences of melting enthalpy, melting entropy, atomic cohesive energy. Moreover, the above modeling has been utilized to determine the size-dependent continuous binary solution phase diagrams. These thermodynamic approachs have extended the capability of the classical thermodynamics to the thermodynamic phenomena in the nanometer regime.
Direct White Light Nanophosphors
Authors: Nanda Karuna Kar
Published: July 2010

White light emission based on semiconductor nanostructures represents a new technology platform for solid state lighting. The major advantages are the easy synthesis and tuning of color emission in the visible range and the high optical stability of nanostructures. This chapter summarizes the materials that can be used as white light nanophosphors.
Nanostructured Solar Cells
Authors: Vigil Elena
Published: July 2010

Novel types of solar cells based on nanostructured materials are intensively studied because of their prospective applications and interesting new working principle – essentially due to the nanomaterials used They have evolved from dye sensitized solar cells (DSSC) in the quest to improve their behavior and characteristics. Their nanocrystals (ca. 10-50 nm) do not generally show the confinement effect present in quantum dots of size ca. 1-10nm where electron wave functions are strongly confined originating changes in the band structure. Nonetheless, the nanocrystalline character of the semiconductor used determines a different working principle; which is explained, although it is not completely clear so far,. Different solid nanostructured solar cells are briefly reviewed together with research trends. Finally, the influence of the photoelectrode electron-extracting contact is analyzed.
Size Effect and Shape Stability of Nanoparticles
Authors: Rodríguez-López Jose Luis , Montejano-Carrizales J.M. , Palomares-Báez J.P. , Barrón-Escobar H. , Velázquez-Salazar J. Jesús , Cabrera-Trujillo J.M. , José-Yacamán Miguel
Published: July 2010

Nanoparticle research disciplines—chemical synthesis, applied physics and devices based on their physical-chemical properties, and computational physics—have been very active fields for the last 15 years or so, because of the potential and current applications in medicine, catalysis, energy storage, environment and electronics applications. This wide spectrum of disciplines and their applications keep metallic nanoparticles as one of the most promising nanostructures and their research as one of the cornerstones of nanotechnology. In this contribution we present a comprehensive and extended geometrical description for the most common shapes and structures for metallic nanoparticles, as well as experimental results for these geometries with some variations given by truncations.
αShape, Birth of one Universal Parameter?
Authors: Guisbiers Grégory
Published: July 2010

The description of different effects observed in nature by only one general equation is the “Holy Grail” for all physicists. This goal has been achieved for characteristic temperatures through a top-down approach (studying size effects from macroscopic laws) and is presented in this chapter. Here, we show the general equation based on the surface area to volume ratio of nanostructures and statistics (Fermi-Dirac or Bose-Einstein) followed by the particles involved in the investigated phenomena. From the distinction between fermions and bosons, so-called particles which follow a Fermi-Dirac or a Bose-Einstein statistics respectively, this equation indicates the universal behaviour of size and shape effects on different material properties like melting, ferromagnetism, vibration and superconduction. The same shape parameter used in this universal equation can be used to determine the melting enthalpy, the phase diagrams of alloys, the energy bandgap and also the creep behavior of nanomaterials. Theoretical predictions show satisfactory agreement with experimental data taken from literature.
Size Effects in Amorphous Nanosolids
Authors: Ganguli Dibyendu
Published: July 2010

Compared to information on nanocrystals, that on amorphous nanosolids is on the whole much less organized. On the other hand, growth of structural data in recent years on the latter, that deal with the range of atomic order (short range order and beyond), coordinations of core and surface atoms and similar aspects in amorphous nanoparticles through computer simulation and other techniques, has been very impressive. Similar generation of information is also true for physical phenomena like crystallization and melting. Finally, interesting properties revealed through experimentations point toward important applications. The present article makes a brief survey of these areas and attempts at reaching certain conclusions mostly specific for amorphous nanostructures with respect to the crystalline counterparts. The article analyzes the structural data to try and explain different properties of amorphous nanosolids and also their position in the applications scenario.
The Synthesis of Nanostructured and Nanometer-Sized Systems
Authors: Delogu Francesco , Arca Elisabetta , Shvets Igor V.
Published: July 2010

The present chapter deals with the difficult task of giving a brief survey of the synthetic routes employed to prepare materials with characteristic features on the nanometer scale. Definitions and general concepts regarding nanostructured and nanometer-sized materials are shortly tackled in the introductory part, which is followed by an overview of the most important approaches developed to synthesize such materials. No attempt is made to create a comprehensive and detailed synopsis of the experimental methods currently available. Rather, attention is focused on a selected number of general methodologies, the choice of which can be usually motivated by a mix of historical perspective, scientific significance and technological potential. So-called “top-down” approaches are discussed first, whereas the second part of the chapter is devoted to “bottom-up” ones. The former group includes mechanical processing, melt quenching, and de-vitrification methods. Sonochemistry, pulsed laser ablation, wet chemical synthesis, sol-gel processing, microwave processing, spray pyrolysis, flame synthesis, inert gas condensation, vapor deposition, and vapor-liquid-solid growth form instead the latter group.
Development of Positive Electrode Materials for the High Rate Lithium Ion Battery by Nanostructure Control
Authors: Hosono Eiji , Matsuda Hirofumi , Okubo Masashi , Kudo Tetsuiichi , Fujihara Shinobu , Honma Itaru , Zhou Hao Shen
Published: July 2010

Previously, we reported the fabrication of Na0.44MnO2 and LiMn2O4 single crystalline nanowire structure. Moreover, these electrodes showed good high rate property as lithium ion battery, because the nanostructure electrode is suitable for high rate lithium ion battery. Especially, the fabrication of LiMn2O4 single crystalline nanowire was very interesting results because the synthesis of 1-dimesional single crystal structure of LiMn2O4 is very difficult based on cubic crystal structure without anisotropic structure. The LiMn2O4 single crystalline nanowire was obtained thorough the self template method using Na0.44MnO2 nanowire. In this paper, we report the fabrication of Na0.44MnO2 and LiMn2O4 single crystalline nanowire structure and the property of lithium ion battery as review paper.
Preparation and Evaluation of TiO2 Nanoparticle Thin Films by Electrophoresis Deposition
Authors: Ito Kazuatsu , Sato Yuuki , Adachi Motonari , Mori Yasushige , Yoshikado Shinzo
Published: July 2010

The transparency and uniformity of thin films of titanium oxide (TiO2) are important factors in determining the characteristics of photocatalysts and dye-sensitized solar cells. Synthesized TiO2 nanoparticles were deposited by constant-current electrophoresis deposition in ion-free water and ethanol. The number of cracks was reduced when ethanol was used instead of water. TiO2 nanoparticle thin films produced using a short deposition time had no apparent cracks and a high optical transparency. Moreover, thick TiO2 nanoparticle thin films, which have high optical trans-parency and no apparent cracks, could be deposited by repeating short-time deposition in ethanol.
Preparation of Barium Titanate Nanoparticles by Particle Growth Control
Authors: Kondo Shuhei , Kita Tatsuya , Pulpan Petr , Moriyoshi Chikako , Kuroiwa Yoshihiro , Wada Satoshi
Published: July 2010

Barium titanate (BaTiO3) nanoparticles were prepared by a two-step thermal　decomposition method using barium titanyl oxalate nanoparticles of size 30 nm with and without dry-jet milling. Dry-jet milled barium titanyl oxalate nanoparticles (BTO-B) were well-dispersed whereas those without the dry-jet milling procedure (BTO-A) were partially aggregated. A heat annealing of obtained BaTiO3 nanoparticles at the same temperature resulted in crystallite sizes of the BTO-A derived BaTiO3 nanoparticles much smaller than those of the BTO-B derived. A mesoscopic particle structure analysis of revealed much thinner surface cubic layer thickness of the BTO-B derived BaTiO3 nanoparticles compared with the BTO-A derived BaTiO3 nanoparticles. This indicated the particle growth rate to be the most important parameter for the surface cubic layer thickness determination. A relationship between the surface cubic layer thickness and the particle growth rate was investigated precisely in this study.
Thermal Property of BaO-TiO2-GeO2 Glass and the Crystallization Behavior
Authors: Yamazaki Yoshiki , Masai Hirokazu , Takahashi Yoshihiro , Fujiwara Takumi
Published: July 2010

Correlation between surface crystallization behavior of BaO-TiO2-GeO2 (BTG) glass and the thermal stability parameter measured by Differential Thermal Analysis (DTA) was examined. We have proposed normalized thermal stability ΔTnorm of the BTG glass using crystallization temperature (Tx), glass transition temperature (Tg), and melting temperature (Tm). It was found that surface crystallization occurred in the BTG glass possessing ΔTnorm (= (Tx-Tg)/Tm) value larger than 0.08. Compared ΔTnorm value of bulk state with that of powdered state, it has been revealed that Ba2TiGe2O8 was precipitated independently of thermal stabilities whereas BaTiGe3O9 or BaGe4O9 was precipitated in precursor glasses possessing high surface stability.
Dispersion of Barium Titanate and Strontium Titanate Nanocubes and their Selective Accumulations
Authors: Wada Satoshi , Nozawa Ai , Iwatsuki Shogo , Kuwabara Tetsuo , Takei Takahiro , Kumada Nobuhiro , Pulpan Petr , Uchida Hiroshi
Published: July 2010

Barium titanate (BaTiO3, BT) and strontium titanate (SrTiO3, ST) nanocube particles were prepared by a solvothermal method. The prepared particles were collected by a centrifugal separator. The X-ray diffraction (XRD) measurement and a transmittance electron microscope (TEM) observation confirmed the formation of perovskite BT and ST nanocube particles with sizes of around 17 nm. These nanocube particles were monodistributed in hexane with tri-n-butylphosphine oxide (TBPO) as dispersant, separately, and then, the accumulations composed of the BT and ST nanocubes were built up using a selective catalytic reaction between 3-bromopropylphosphonic acid (BP) and aminomethylphosphonic acid (AM) as smart glue. The TEM observation confirmed that a part of accumulations showed a hetrointerface connection between BT and ST.
Synthesis and Characterization of CaZnGe2O6
Authors: Hatakeyama Hirotoshi , Narumi Yousuke , Uematsu Kazuyoshi , Ishigaki Tadashi , Toda Kenji , Sato Mineo
Published: July 2010

We report the synthesis and photocatalytic activity of CaZnGe2O6, which contains Ca2+ ions and one-dimensional GeO4 chains (Ge4+: d10 electronic configuration). This sample demonstrated the water splitting phenomenon by loading with RuO2 cocatalysis. Moreover, Ln-doped CaZnGe2O6 (where Ln = La, Ce, Pr, Nd, or Sm) shows a higher photocatalytic activity than CaZnGe2O6.
Effects of H2O Addition on One-Step Liquid-Phase Synthesis of Highly Aligned Carbon Nanotubes
Authors: Yamashita Shunsuke , Kikitsu Tomoka , Yamaguchi Yoshihiro , Yamagiwa Kiyofumi , Kuwano Jun
Published: July 2010

Highly aligned carbon nanotube arrays (HACNTAs) were synthesized on a stainless steel substrate from a methanol solution of Co(Ⅲ) acetylacetonate by the one-step liquid-phase synthesis, and effects of H2O addition on the HACNTA growth were examined. The growth rate was considerably accelerated, and the lifetime of the catalysts was prolonged by addition of a small amount of H2O. HACNTAs with over 400 m thickness were formed on the side surfaces of the substrate by resistance-heating for one hour. This suggests that the added H2O removes deposited amorphous carbons from the catalyst surfaces and consequently accelerates the growth rate.
Effect of Substrate on Growth Mechanism of Flower Structured InN Fabricated by APHCVD
Authors: Sakamoto Naonori , Sugiura Haruka , Fu De Sheng , Wakiya Naoki , Suzuki Hisao
Published: July 2010

InN belongs to the III-group nitride materials and is known to have a low decomposition temperature which causes intractable grain growth compared to the other nitrides, GaN, AlN, etc. We prepared InNs with a flower-like shape as well as film structure by Atmospheric Pressure Halide CVD process, in which InN is synthesized by CVD under atmospheric pressure. In the present study, growth mechanisms of the flower structured InN prepared on Si(100) and a-plane sapphire substrates is reported.
Effect of Ba Addition on Electrical Characteristics of Bi-Based ZnO Varistors
Authors: Fukumori Ai , Takada Masayuki , Akiyama Yuji , Sato Yuuki , Yoshikado Shinzo
Published: July 2010

With the goal of fabricating low-breakdown-voltage varistors, the effect of adding Ba to ZnO varistors on the ZnO grain size was investigated. Grain growth of ZnO could be markedly promoted by adding both Ba and Bi. The maximum grain size was approximately 150 μm and the minimum varistor voltage was approximately 12 V/mm. However, it had relatively poor tolerance characteristics for electrical degradation. It is speculated that when adding both Ba and Bi to a Mn–Co-added ZnO varistor, it is necessary to form the molten phases of Ba and Bi to promote grain growth of ZnO. It is also conjectured that the growth of ZnO grains is not promoted when Ba and Bi do not coexist in the molten phase because Ba forms compounds with Mn independently with the addition of small amounts of Bi.
Preparation of Barium Titanate Grain-Oriented Ceramics and their Piezoelectric Properties
Authors: Mori Rintaro , Pulpan Petr , Hayashi Hiroshi , Nagamori Yoshitaka , Yamamoto Yuichi , Uchikoshi Tetsuo , Suzuki Tohru S. , Wada Satoshi
Published: July 2010

Barium titanate (BaTiO3, BT) 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. BT grain-oriented ceramics with higher relative density (Drel) over 95 %, high degree of orientation along [110] direction (F110) over 80 % and grain sizes around 30 µm were successfully prepared using only the template particles. The relationship between microstructures and piezoelectric constant (d33) was investigated. The higher F110 was, the higher Drel and the smaller grain size were required for enhancement of the piezoelectric properties.
Improvement of Compact X-Rays Source Using Uniaxially Polarized LiNbO3 Single Crystal
Authors: Guan Yang , Fukao Shinji , Ito Kazuyuki , Nakanishi Yoshikazu , Sato Yuuki , Ito Yoshiaki , Yoshikado Shinzo
Published: July 2010

X-ray radiation using pyroelectric crystal is intermittent and the X-ray intensity is low and unstable compared with a conventional X-ray radiation method, such as X-ray tube. It is expected that the X-ray intensity becomes stable if electric field intensity and supply of electron are stable. In this study, to use X-ray radiation equipment as an electron source, tandem-type X-ray radiation equipment which is composed of two LiNbO3 single crystals polarized in a z-axis is proposed. When the temperature gradient for each crystal was the same, the X-ray intensity became approximately 6 times higher at a maximum. When the temperature gradient for each crystal was reversed, the period of X-ray radiation became approximately two times longer and the X-ray intensity became approximately 20 times higher at a maximum. Moreover, the stability of X-ray radiation for the repetition of temperature could be improved.
Fabrication of Dye-Sensitized Solar Cells with Electrolyzed TiO2 Nanotube Array Films
Authors: Nakamura Takahiro , Hayashi Kazuho , Masahiro Asahara , Ogihara Takashi
Published: July 2010

A TiO2 nanotube array film was synthesized by the anodic oxidation of a Ti plate in an NH4F electrolyte. The film was broken into nanotubes by carrying out ultrasonication. The nanotube powder was mixed with TiO2 nanoparticle powder to form a paste. The paste was used in the fabrication of ceramic porous electrodes of dye-sensitized solar cells.
The Influence of Some Technological Parameters on the Fracture Toughness of Ceramic Materials
Authors: Goanta Viorel , Mares Marian
Published: July 2010

In order to determine the fracture toughness of the materials presenting high hardness values in the superficial layers, the Vickers micro-indentation was imposed as a reliable procedure. That method became attractive because of the relative simplicity of the experimental technique and because of its low cost. There are several calculus relationships that could be applied using the data provided by that method, in order to determine the material fracture toughness. The determination of fracture toughness using the Vickers indentation method is based on the analysis of radial cracks propagation, from the corners of the indentation trace. The length of these cracks is connected with the material fracture toughness, on the basis of some semi-empirical calculus relations that are taking into account the indentation load and some physical characteristics of the test material, as Young’s modulus and Poisson’s coefficient.
In the present paper, fracture toughness was determined on a series of ceramic samples, made of the same material, but with different geometrical shapes and obtained by applying different technological procedures. The influence of some technological parameters on the fracture toughness was evaluated. The material fracture toughness was determined, into the vicinity of the propagated cracks (in a sample that could be a final product), on an area with a specified geometric contour.
As a preliminary stage, a step by step FEM analysis was made, into the Vickers indentation material region, for different values of indentation load. In this manner, it was proved that the maximum stress value, on the perpendicular direction, as related to the crack diagonal plane, is always located at the peak of the indentation trace, and that is the effective start-point of cracking, for this type of indentation.
FEA of Dynamic Behavior of Top Hat Bonded Stiffened Composite Panel
Authors: Mohamad G. , Tarfaoui Mostapha , Bertram Volker
Published: July 2010

In this work the dynamic responses of bonded top hat stiffened panel have been studied by using finite element analysis model (Abaqus). A symmetrical 2D model was performed and used in the simulations. In the first part, dynamic behavior and impact speed effects at such composite structure have been studied. In the second part, other simulations were carried out by using cohesive elements proposed to predict the delamination might happen under such loading.
Manufacturing of Carbonaceous Materials Based on Olive Stones Biomass for Electrochemical Applications
Authors: Pikasi Anastasia , Georgiou Pantelitsa , Simitzis Johannis
Published: July 2010

Carbonaceous materials have been obtained by pyrolysis of composites based on olive stones biomass, novolac resin as binding agent, with or without an aromatic compound (naphthalene). The pyrolysis residue at 1000 °C is 40 w% and its electrical conductivity, σ, is 0.13 S/cm. Small cylindrical specimens have been manufactured and pyrolyzed at 1000 °C in order to be used as electrodes. Platinum was electrodeposited by cyclic voltammetry on these specimens using them as working electrodes or on commercial carbon fibres, respectively, for correlating purposes. The morphology of both carbon materials, used as electrodes, was characterized by SEM images and the presence of Pt was determined based on EDS analysis. The crystallographic planes of Pt–carbon of Pt deposited on carbon materials were characterized with XRD. The oxidation of ethanol from a proper solution using the carbonaceous specimen and the carbon fibres as working electrodes was examined by cyclic voltammetry.
Physicochemical and Electro-Rheological Characterization of Kaolinite / CMS / Silicone Oil Fluid
Authors: Reiss Thomas , Laribi Saoussen , Fleureau Jean-Marie , Tassin Jean Francois
Published: July 2010

The aim of this study is to elaborate electro-rheological fluids based on kaolinite. the scientific characterization made it possible the identification of the composite nature and the checking of the intercalation of the polymer among the clay particles The rheological behaviour of the fluid depends on the electric field. A yield stress of the suspensions is observed, which increases with the applied electric field.
An interpretation based on the different modes of association between the clay particles is proposed to account qualitatively for the observed behaviour.
Influence of Strain Rate on the Yielding Behavior and on the Self Heating of Thermoplastic Polymers Loaded under Tension
Authors: Hadriche Ismail , Ghorbel Elhem , Masmoudi Neila , El Halouani Foued
Published: July 2010

The effect of strain rate on the mechanical behavior of thermoplastic polymers (Polymethyl methacrylate, Polycarbonate and Polyamide 66) has been studied. Deformation tests in tension were conducted over the range of strain rate varying between 2.6 10-4s-1 to 1.3 10-1s-1. The Young’s Modulus E and Yield stress σST evolutions have been identified and modelled as a function of the strain rate. It has been established that, in the range of the considered strain rates, the yielding behavior of PMMA and PC is well described by the Eyring theory while for PA66 the Ree-Eyring theory is successfully used to illustrate the yielding behavior. During tensile tests the specimen surface temperatures were monitored using an infrared camera. Results reveal a significant temperature rise at large deformations for PA66 and PC. As the strain rate increases the temperature is steadily increased with deformation due to plastic work. Hence, for PC and PA66, a significant thermal softening is observed after yielding which affects the stress-strain behavior. Thermo-mechanical coupling during polymer deformation can be considered in the modeling of the mechanical behavior of polymers. No self-heating has been detected for PMMA.
Approximate Solution of the Structural Problems Using Probabilistic Transformation
Authors: Ouhimmou S. , El Hami A. , Ellaia Rachid , Tkiouat M.
Published: July 2010

The aim of this paper is to present a new methodology for the evaluation of the statistical proprieties of the response of structures, based on The Finite Element Analysis (FEA) coupled with the Probabilistic Transformation Method (PTM). Uncertainty modelling with random variables motivates the adoption of advanced PTM for reliability analysis to solve problems of mechanical systems. The PTM is readily applicable in the case where the expression between input and output of structures are available in explicit analytical form. However, the situation is much more involved when it is necessary to perform the evaluation of implicit expression between input and output of structures through numerical models. For this we propose technique that combines the FEA software, and the PTM program to evaluate the Probability Density Function (PDF) of the response where the expression between input and output of structures is implicit. This technique is based on the numerical simulations of the FEA and the PTM by making an interface between Finite Element software and Matlab. Some problems of structures are treated in order to demonstrate the applicability of the proposed technique.
Electrical and Proton Conducting Polymer Based Composite Electrodes Incorporating Fuel Cell Catalysts: Screen Printed Systems Analysed Using Hall Measurements
Authors: Petrik Leslie F. , Ndungu Patrick , Iwuoha Emmanuel Iheanyechukwu
Published: July 2010

40% Pt on carbon black was used to make various inks. Compositions were altered by changing the organic component (2-propanol vs 1,2-¬propanediol), the liquid to solid ratio, and addition of Fullerenes to alter electronic properties. Inks were printed onto Nafion® or bond paper substrates using a Presco screen printer. The inks rheological properties were thoroughly characterized, and screen printed electrodes were characterized using optical microscopy, and hall measurements. Ink formulation had a major effect on final film morphology, with high water ratio formulations optimum for the Nafion® substrate and low water ratios ideal for bond paper. The final film integrity influenced sheet hall coefficients with p-type carriers dominating inhomogeneous films, and n – type carriers dominating well formed films. However hall mobility did not correlate with film thickness. Rheological studies showed that increasing the solid ratios and changing the solvent increased the viscosity, and the storage modulus (G') of between 84 and 224 and viscoelastic behaviour of inks correlated with good print quality.
Amorphous and nc-Si:H Intrinsic Thin Films for Solar Cells Applications
Authors: Halindintwali Sylvain , Knoesen Dirk , Julies Basil A. , Muller Theo , Arendse Christopher J.
Published: July 2010

This contribution discusses the deposition process and properties of intrinsic silicon thin films processed by the hot wire chemical vapour deposition technique. We review some fundamental characterization techniques that are used to probe into the quality of the material and thus decide its susceptibility to be used as the intrinsic layer in solar cells industry. This paper covers the optical, structural and electrical properties of the material. Results from UV-visible and IR spectroscopy, XRD and Raman scattering, X-section TEM as well as dark and photo-currents are given. It is shown that the thermal activation energy is a good measure of the quality of the sample.
Preparation of Atomic Oxygen Oxidant by Electrolysis with Ultrasonic
Authors: Li Lin Bo , Xue Juan Qin , Hong Tao , Wang Miao , Yang Jun
Published: July 2010

The atomic oxygen oxidant—Peroxy-monosulfuric acid was prepared by the method of electrolysis under the condition of with and without ultrasonic. The influence of electrolysis time, electrolyte concentration, electrolytic voltage and the additive concentration on the concentration of oxidant were investigated. The result indicated that with the usage of ultrasonic, combination the cavitation effect and the chemical effect enhanced the concentration of electrolysis oxidant; with the electrolytic time of 3 hours, the electrolytic tension of 6V, the sulfuric acid weight concentration of 35%, the additive concentration of 0.5g/L, the ultrasonic frequency of 40kHz and the power of 150W, the oxidant concentration could reach to 0.9177mol/L. This research is helpful for decreasing the production cost of atomic oxygen oxidant.
Surface Characterization of Oxygen Plasma Treated Nano-SiO2 Sol-Gel Coating UHMWPE Filaments
Authors: Zhang Ying Chen , Shi Feng Jun , He Jian Xin , Wu Hong Yan , Qiu Yi Ping
Published: July 2010

UHMWPE filaments have a low surface free energy and therefore often require a modification of their surface properties before any use. Atmospheric pressure plasmas treatment is a convenient and environmentally friendly way to obtain these modifications by introducing new chemical groups at the surface without affecting the bulk properties. This paper studies the influence of nano-SiO2 sol-gel coating pretreatment on atmospheric pressure plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers when a mixture of 100% helium and 1% oxygen used as the treatment gas. The surface properties of the plasma-treated UHMWPE filaments are characterized using contact angle measurements and ATR-FTIR spectroscopy. The UHMWPE filaments show a remarkable increase in surface free energy after plasma treatment. ATR-FTIR spectroscopy of the plasma-treated UHMWPE filaments reveals that plasma treatment introduces oxygen-containing functionalities on the UHMWPE filaments surface leading to the increased surface free energy.
Study of Cyclohexane Photooxidation over Pt-WO3 Catalysts Mixed with TiO2 under Visible Light Irradiation
Authors: Ichihashi Yuichi , Saijo Shingo , Taniguchi Masaaki , Taniya Keita , Nishiyama Satoru
Published: July 2010

The photooxidation of cyclohexane to cyclohexanone, cyclohexanol and CO2 was carried out by visible light irradiation to tungsten oxide photocatalysts. The physical mixing of tungsten oxide and titanium oxide (WO3+TiO2) led to the high photocatalytic activity. It was speculated that the physical mixing of WO3 and TiO2 took place the charge transfer between WO3 and TiO2, and this inhibited the recombination between electrons and holes on the WO3 surface. The platinum loading on WO3 further developed the photocatalytic activity of WO3+TiO2 photocatalyst. Hence, the degree of the recombination between electrons and holes may dominate the photocatalytic activity of cyclohexane oxidation.
Removal of NO2 and SO2 Using Porous Media Made from Sewage Sludge
Authors: Yoo Yeong Seok , Park Eun Zoo , Ban Hyo Jin , Chae Ho Jun
Published: July 2010

This study was carried out to investigate adsorption characteristics on NO2 and SO2 for two kinds of media, ie the carbonated media and its zeolite coated media with sewage sludge. Porous media was manufactured through processes of drying, extruding, forming, carbonation and washing. Zeolite was coated on the media, and then thermally treated. Test of NO2 and SO2 removal was peformed by detecting NO2 and SO2 concentration at inlet and outlet of the reactor continuously flowing the mixed gas. Zeolite coated media showed higher than carbonization media in removal efficiency of NO2 and SO2. Also, zeolite coated media took shorter time for achieving in 84% removal of SO2 than carbonated media. And, zeolite coated media showed that removal efficiency of NO2 and SO2 maintained high in early stage as well as time elapsing. It make possible the zeolite coated media remove SO2 and NO2 for long time. As a result, micro pore in zeolite could increase breakthrough time and adsorption capability, compared to macro pore in carbonated media. Zeolite coating on porous media would be effective on removal of SOx and NOx.
Influence of Strain Aging on the Microstructure-Property of an X100 Pipeline Steel
Authors: Zhang Xiao Yong , Gao Hui Lin , Ji Ling Kang , Zhuang Chuang Jing
Published: July 2010

The influence of strain aging on the microstructure-property characterization of an X100 pipeline steel was investigated by means of a thermal simulation technique, microscopic analysis method and mechanical properties testing. The experimental steel was prestrained in the tension at 6 pct and then was baked at 150oC, 200oC, 250oC and 300oC for 60 minutes, respectively. The results indicated that the strength and hardeness of test steel X100 increase and the plasticity and toughness decrease with the increasing of strain aging temperature, and it can get a higher ratio of yield to tensile and a lower strain-hardening coefficient which result in lower hardening capacity of X100 pipeline steel. There are two reasons for this strain aging phenomenon. One is the solute atoms of C, N in the α-Fe which Aggregated at the dislocation zones; the other is the compounds precipitation of C, N induced by the dislocations.
Thermoelectric and Transport Properties of In-Filled CoSb3 Skutterudites
Authors: Jung Jae Yong , Park Kwan Ho , Ur Soon Chul , Kim Il Ho
Published: July 2010

In-filled CoSb3 skutterudites (InzCo4Sb12) were prepared and the filling effects on the thermoelectric and transport properties were examined. Seebeck coefficient and Hall coefficient confirmed that all the samples showed n-type conductivity. Temperature dependence of the electrical resistivity suggested that InzCo4Sb12 is a highly degenerate semiconducting material. The thermal conductivity was considerably reduced by In filling and the lattice contribution was dominant.
The Theoretical Research of Constitutive Property, Reactivity and FTIR of Chitosan
Authors: Xue Juan Qin , Wen Dan Dan , Yu Li Hua , Wang Yu Jie , Zhu Jun
Published: July 2010

The structural optimization and the frequency for chitosan monomer, chitobiose and chitotriose with the quantum chemistry abinitio HF and the density functional B3LYP method by choosing 6-311 + G (d, p) as the basis set were calculated and studied. For its three rotational isomers, gauche-trans (gt), gauche - gauche (gg), and trans-gauche (tg), the calculations comparatively were performed respectively. The charge distribution and frontier molecular orbit were analyzed by using the method of natural bond orbital (NBO). The calculated IR spectrum was compared with the experimental data. The results showed that the three rotational isomers gt, gg, and tg can stably existed in chitosan with the stability order gg﹥gt﹥tg. Its highest occupied molecular orbital (HOMO) was provided primarily by nitrogen atom and its lowest unoccupied molecular orbital (LUMO) was provided mainly by the oxygen atom; Its reaction active sites were concentrated in -NH2 and –OH. The calculated infrared spectra were in good agreement with the experimental values.
Dynamic Compression Behavior of Lotus-Type Porous Iron
Authors: Tane Masakazu , Kawashima Tae , Horikawa Keitaro , Kobayashi Hidetoshi , Nakajima Hideo
Published: July 2010

Dynamic and quasi-static compression tests were conducted on lotus-type porous iron with porosity of about 50% using the split Hopkinson pressure bar method and universal testing machine, respectively.　In the dynamic compression parallel to the pore direction, a plateau stress region appears where deformation proceeds at nearly constant stress, while the plateau stress region does not appear in the quasi-static compression. The plateau stress region is probably caused by the buckling deformation of matrix iron which occurs only in the dynamic compression. In contrast, the compression perpendicular to the orientation direction of pores exhibits no plateau-stress regions in the both dynamic and quasi-static compression.
Effect of Transfer Velocity on Porosity of Lotus-Type Porous Aluminum Fabricated by Continuous Casting Technique
Authors: Iio Yutaro , Ide Takuya , Nakajima Hideo
Published: July 2010

Lotus-type porous aluminum was fabricated by continuous casting technique in mixture gas of hydrogen and argon at various transfer velocities in order to understand formation process of pores. The porosity and pore diameter decrease with increasing transfer velocity. The transfer velocity dependence of the porosity in lotus aluminum is different from that in other lotus metals such as stainless steel and copper. It is considered that the difference is attributed to lower solubility in aluminum than that in other metals.
Effect of Addition of NiO Powder on Pore Formation in Lotus-Type Porous Carbon Steel Fabricated by Continuous Casting
Authors: Kashihara Makoto , Yonetani Hiroshi , Suzuki Shinsuke , Nakajima Hideo
Published: July 2010

Lotus-type porous carbon steel (lotus carbon steel) plates were fabricated by continuous casting technique in a pressurized nitrogen atmosphere. The experiments were done both with adding 0.3wt% of NiO powder in molten carbon steel in a ceramic crucible and without NiO powder. The lotus carbon steel fabricated without NiO powder under nitrogen pressures of 0.1 and 0.5 MPa had single pores which grew independently. On the other hand, the lotus carbon steel fabricated with adding NiO powder had pores which coalesced each other and became in irregular shapes. Under nitrogen pressure of 2.5 MPa, the pores formed with adding NiO powder were smaller than that formed without NiO powder. The porosity increased by adding NiO powder in every pressurized nitrogen atmosphere. From these results, NiO powder in molten carbon steel is considered to act as nucleation sites for pores at the solid-liquid interface and to increase of the pore number.
Formation of Oxide Nanotubes and Bamboo-Like Structures via Oxidation of Cu, Fe and Ni Nanowires
Authors: Matsubayashi Gen , Nakamura Ryusuke , Tsuchiya Hiroaki , Fujimoto Shinji , Nakajima Hideo
Published: July 2010

The formation process of oxide nanotube via metal oxidation reaction was studied by transmission electron microscopy for Cu, Fe, and Ni nanowires. Cu2O and Fe3O4 nanotubes were formed after the oxidation of Cu and Fe nanowires with a diameter of 55 nm in air at 423 and 573 K for 3.6 ks, respectively. Both Cu2O and Fe3O4 nanotubes had a cylindrical interior pore with uniform diameter. On the other hand, Ni nanowires became bamboo-like structures of NiO with separate interior pores after oxidation at 673 K for 7.2 ks. The formation of the interior pores in Cu2O and Fe3O4 nanotubes and NiO bamboo-like structures can be explained by the rapid outward diffusion of metal ions through the oxide layers and the clustering of excess vacancies.
Study on Bonding Performances of Air Plasma Treated FRP
Authors: Xiong Yu Lin , Gu Ji You , Hu Ying Cheng
Published: July 2010

This paper reports on the effect of air plasma on the FRP surface wettability via change of the water contact angle. The aim is to alter the surface in a manner and scale resulting in stronger bonding strength between FRP and wood. The specimens are exposed to the direct current discharge. The irradiation time and power are variables. Goniometry is employed to determine the contact angle of FRP surface. The plasma treatment leads to radical generation and activation of such agents as oxygen, thus the surface contact angle decreases significantly. The shear strength of samples of wood reinforced by treated FRP is also given to show the bond quality at the FRP-wood interface.
Strength and Densification of Ni/Al2O3 Membrane Compacted with Uniaxial Pressing and CIP for Hydrogen Separation: Influence of Pressing Process
Authors: Vichaphund Supawan , Atong Duangduen
Published: July 2010

In our previous studies, 10-40wt%Ni/Al2O3 membrane was prepared by uniaxial pressing and sintered at 900 to 1400°C for 2 h. It was found that 10wt%Ni/Al2O3 membrane sintered at 1400°C showed the highest physical and mechanical properties. Thus, this work we focused on the effect of different pressing processes on the properties of Ni/Al2O3 membrane with longer soaking time. Firstly, 10-40wt%Ni and Al2O3 powders were mixed by dried ball-milling. Then, the mixture powder was pressed to form a bar shape by two different processes; uniaxially pressing (No CIP) and uniaxially pressing followed by cold isostatic pressing (CIP) at 250 MPa for 5 min. All Ni/Al2O3 specimens from two pressing routes were sintered at 1400°C for 4h under air atmosphere and reduced at 900 °C under H2 (99.99%). From the results, it was found that the densification process affected to physical and mechanical properties of Ni/Al2O3. The CIPed - 10wt%Ni/Al2O3 membrane sintered at 1400°C for 4 h showed the highest relative density and flexural strength of 76% and 106 MPa with the lowest pore size (78 nm) and 17% porosity. The addition of nickel content gradually decreased physical and mechanical properties of Ni/Al2O3.
Study on Thermal Environmental Characteristics of Water-Retentive Asphalt Pavement
Authors: Pyun Hee Bum , Kim Ree Ho , Lee Sang Ho , Park Jong Bin
Published: July 2010

Urban area may be warmer than surrounding regions due to asphalt and concrete for roads, buildings, and other artificial structures. Especially, pavements have become an important contributor to this effect by altering land-cover over significant portions of an urban area. Therefore, researchers have studied ways to reduce the heat island effect such as cooling pavement, porous pavements such as water-retentive or water absorbing pavements. Accordingly, this study aims at the development of water-retention asphalt pavement for urban areas in order to solve problems related to the distortion of water cycle and the heat island phenomena. Experimental results indicated that asphalt pavement using developed water retaining material was effective to decrease its surface temperature compare to other pavements. A correlation between air temperature and surface temperature of the pavement was obtained to estimate the efficiency of the developed pavement materials.
Red Tide Inactivation by Silver Doped TiO2 Produced in Sono-Chemistry Method
Authors: Cho Sung Hun , Fu Zheng Yi , Niihara Koichi , Obregon-Alfaro S. , Lee Soo Wohn
Published: July 2010

Nano-technology is a super microscopic technology to deal with the structures of 100 nm or smaller. This technology also involves the developing of TiO2 materials or TiO2 devices within that size. The aim of the present paper is to synthesize the silver doped nano-TiO2 by Sonochemistry method and to evaluate the effect of different percentages (0.2-1.5%) of silver load on TiO2 in the algae inactivation, The sample were characterized by using different techniques as XPS, TEM, SEM. Photo-catalytic activity of Silver doped TiO2 were evaluated through the inactivation of red tide (Cochlodinium) using UV-irradiation (315-400nm). The best result was found with silver doped TiO2.
The Dominant Factor Analysis of Production Technology of Poplar LVL Based on Grey Theory
Authors: Li Feng , Hu Ying Cheng
Published: July 2010

Wood is one kind of natural renewable eco-material. Laminated veneer lumber (LVL) is an engineered wood product made from veneers glued together with parallelly oriented grains under heat and pressure. This paper designed Poplar LVL production experiments under different process conditions, and measured the mechanical properties of poplar LVL specimens under different experimental conditions. In this study, grey theory was used to analyze the influences of different production processes on the mechanical properties, such as press duration, press temperature, pressure and adhesive spread. The result showed that, it is feasible that grey theory is used to analyze the influence level of production technology of poplar LVL on the mechanical properties. So this paper offered a new method to analyze and design the production technology of LVL.
Development of Non Explosive Insulating and Fire Proof Materials Using Porous Industrial Byproducts
Authors: Kim Soo Ryong , Kwon Woo Teck , Kim Byung Ik , Kim Y. , Ha Sang Wook
Published: July 2010

The effectiveness of bottom ash on the mechanical and physical properties of lightweight cement mortar for fire proofing application is investigated in this study. Bottom ash is well known that it can make it possible to decrease the thermal conduction in mortar by their porous structure. Physical properties of bottom ash including pozzolanic activity and compressive strength test were measured to decide the replacement amount in formulation as well as chemical composition. This study was undertaken on the use of bottom ash as fine aggregate in fire proofing mortar. Various dosage of bottom ash such as 25%, 50%, 75%, 100% were evaluated by several measurement. We found out there were serious correlation between specific gravity and thermal conductivity, so other porous materials were also investigated to decrease the thermal conductivity of cement mortar as well as bottom ash. In this study, the researches on the mixing proportion were mainly performed to design specification of spraying fire proofing mortar. Based on the laboratory test results, we’d like to suggest the proper adding amount of bottom ash by evaluation of consistency and strength development and then optimum mixing proportions of spraying fire proofing mortar using bottom ash by various evaluations.
Decomposition Characteristics of Wood Using Supercritical Methanol for Biodiesel Production
Authors: Oh Sea Cheon , Kim Y. , Kim Soo Ryong
Published: July 2010

In this work, the decomposition characteristics of wood using supercritical methanol have been studied. The kinetic analysis was carried out for three heating rates of 5.2, 11.6 and 16.3 oC/min. And the liquid products analysis has been performed for reaction temperatures of 300-320 oC and reaction times of 0-120 min, respectively. The activation energies of wood decomposition in supercritical methanol were 45.2-48.8 kJ/mol, depending on the heating rates. And the reaction orders were 0.25 for all heating rates. And the liquid product has been analyzed by GC-MS. From this work, the yields of liquid product increased as increasing of reaction temperature and reaction time. And it was also found that the components of liquid products were mainly acetic acid, latic acid, pentanol and phenol.