bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method of Analyzing Fatigue Cracks in Cast Iron by Measuring Vibration Characteristics Caused by Impact Striking
Authors: Honjoh Katsuhiko , Jun-ichi Masuda Jun-ichi Masuda
Published: October 2002

This paper describes a technique for evaluating fatigue cracks in cast iron by analyzing vibration caused by hammer striking. The relationship between the vibration characteristics and cracking damage is quantitatively investigated for gray cast iron by using bending load tests and slitting. It is found that the resonant frequency decreases and the attenuation constant increases as cracks extend. The stage of crack extension can therefore be quantified by determining the typical relation between the attenuation constant and resonant frequency. We theoretically investigate the speed of crack growth and the destruction process of cast iron by determining the relationship between the reduction of resonant frequency caused by cracks to the stress intensity factor and stress cycles in the fatigue model. Based on the experimental results, we have devised a manhole cover diagnosis technique and we have developed a portable tester that can evaluate cracking damage of covers in the field.
Can Electric Field Influence the Sensitivity of CR-39 Detector?
Authors: Takeda Matiullah , Kudo Katsuhisa
Published: October 2002

Studies have been carried out to investigate the effect of electric field on the sensitivity of CR-39. Samples of CR-39 were exposed to neutrons and α particles under different electric field values and etched. From the measured track densities and diameters, CR-39 sensitivity and etching rates were determined. It was found that the application of voltage increases etching rates, but the sensitivity of CR-39 remains unchanged.
High-Performance Superthin Oxide/Nitride/Oxide Stacked Dielectrics Formed by Low-Pressure Oxidation of Ultrathin Nitride
Authors: Liu Han-Wen , Su Huan-Ping , Huang-Chung Cheng Huang-Chung Cheng
Published: October 2002

High-performance superthin oxide/nitride/oxide (O/N/O) stacked dielectrics have been successfully achieved by oxidizing ultrathin nitride films in low-pressure dry oxygen at 850° C for 30 min. The low leakage current and the high reliability of this O/N/O structure are attributed to the growth of the top oxide on the nitride, which is confirmed by Auger electron spectroscopy (AES) depth profiles and step-by-step diluted-HF etching results. The commonly used wet oxidation of the nitrides at atmospheric pressure cannot attain an effective oxide thickness of as low as 46 Å. Furthermore, the dry oxidation of nitrides at atmospheric pressure can only yield a nitride/oxide (N/O) structure, which results in high leakage current. Therefore, our novel technique is promising for future dynamic-random-access-memory (DRAM) technology.
Effect of γ-Irradiation on Optical Second Harmonic Intensity of Electrically Poled Silica Glass
Authors: Tanaka Katsuhisa , Kashima Kenichi , Hirao Kazuyuki , Soga Naohiro , Yamagata Shigeru , Mito Akihiro , Nasu Hiroyuki
Published: October 2002

Optical second harmonic generation has been observed in γ-irradiated and subsequently electrically poled silica glasses. The second-order nonlinear susceptibility, as well as the second harmonic intensity, increases with an increase in the γ-ray dose. The larger second harmonic intensity of γ-irradiated silica glasses may be related to the defects created by γ-irradiation.
Optical Bond Gap and Tauc Gap in a-SiOx:H and a-SiNx:H Films
Authors: Ikurou Umezu Ikurou Umezu , Ken-ichi Miyamoto Ken-ichi Miyamoto , Naomichi Sakamoto Naomichi Sakamoto , Keiji Maeda Keiji Maeda
Published: October 2002

Changes in the joint density of state (JDOS) of a-SiOx:H and a-SiNx:H films withxwere investigated by optical measurements. The optical bond gapE0which corresponds to the bonding-antibonding splitting energy was deduced from the dispersion of the refractive indices based on a single-oscillator model. The energy of the Si-Si bond,E0Si-Si, was estimated fromE0. The Tauc gap energyEtand the energy width of the linear tail were determined from optical transmission spectra. The correlation among these characteristic energies was investigated to estimate the JDOS in these alloys. It was found thatE0Si-Siincreases withx, while the bandwidth of JDOS derived from the Si-Si bond is kept constant for both a-SiOx:H and a-SiNx:H systems. This suggests that the increase in the Tauc gap energy is due to the increase in Si-Si bond energy rather than the change in the energy width of the Si-Si-bond-derived JDOS.
Effects of Different Cation and Anion Interdiffusion Rates in Disordered In0.53Ga0.47As/InP Single Quantum Wells
Authors: Shiu Wai-Chee , Micallef Joseph , Ng Isaac , Li E. Herbert
Published: October 2002

The effects of different cation and anion interdiffusion rates when disordering In0.53Ga0.47As/InP single quantum wells are investigated using an error function distribution to model the compositional profile after interdiffusion. The early stages of disordering result in a spatially dependent strain buildup, which can be either compressive or tensile. The effects of this strain profile and the compositional distribution give rise to interesting carrier confinement profiles after disordering. A significantly faster cation interdiffusion rate produces a red shift of the ground-state transition energy, which with prolonged interdiffusion saturates and then decreases. A significantly higher anion interdiffusion rate causes a blue shift in the ground state transition energy, and shifts the light hole ground state above the heavy hole ground state. The results from the model are compared with reported experimental results which have been interpreted in terms of different interdiffusion rates on the two sublattices.
Dependence of SiC Blue Light-Emitting Diode Efficiency on the p-Type Layer Growth Temperature
Authors: Matsushita Yasuhiko , Uetani Takahiro , Kunisato Tatsuya , Suzuki Junko , Ueda Yasuhiro , Yagi Katsumi , Yamaguchi Takao , Tatsuhiko Niina Tatsuhiko Niina
Published: October 2002

Dependence of SiC blue light-emitting diode (LED) efficiency on the p-type layer growth temperature in the liquid-phase epitaxial process was investigated. The external quantum efficiency of LEDs fabricated at a lower growth temperature was higher than that of those fabricated at a conventional growth temperature of 1720° C and maximized at a growth temperature of 1530° C. In this study, luminous intensity of 32 mcd was obtained at a forward current of 20 mA (λ P=467 nm).
Influence of Microcrystallite Size on Photodarkening Effects in CdS-Doped Glasses
Authors: Miyoshi Tadaki , Matsuki Hirobumi , Naoto Matsuo Naoto Matsuo
Published: October 2002

Size dependence of photodarkening effects in CdS-doped glasses was investigated using luminescence and electron spin resonance (ESR). As the microcrystallite size decreases, the ESR signal associated with the photodarkening effects increases. This result indicates that the photoinduced centers responsible for the photodarkening effects are created in the interface region between CdS microcrystals and glass matrix.
Characterization of Ba1-xKxBiO3 Superconducting Thin Films for Three-Terminal Devices
Authors: Suzuki Seiji , Iyori Masahiro , Yamamoto Tetsuya , Takahashi Kazuhiko , Yorinobu Yoshisato Yorinobu Yoshisato
Published: October 2002

The physical parameters of a Ba1-
x

K

x

BiO3 (BKBO) superconductor have been successfully estimated by measuring the Hall effect and optical reflectivity spectra for epitaxial thin films. The results of these measurements at room temperature indicated that the optimized BKBO thin film has a carrier density of 5.0×1021 cm-3 and an effective mass of 0.9m
0. Supposing the free-electron model, Fermi energy of BKBO could be estimated to be 1.2 eV
. Using these parameters, the quasi-particle transmission probability was also calculated for the BKBO/Nb-doped SrTiO3 junction.
Co Substitution Effect on Magnetic and Magnetostrictive Properties of DyFe 2
Authors: Lü Ruo-yang , Hashimoto Takasu , Toriyama Tamostu , Funayama Tomomi , Sahashi Masashi , Tang Yun-zun
Published: October 2002

The Co substitution effect on the magnetostrictive properties of DyFe2 has been investigated using magnetic measurement. The specific saturation magnetization σs of the Dy(Fe1-x
Cox)2 compounds firstly decreases with x and then increases. The magnetostriction constant λt of these compounds increases with x monotonically. These phenomena are been discussed.
Epitaxial Fe72Co28(112) Films Grown on MgO(110) Substrates
Authors: Tomita Hiroshi , Sawabe Atsuhito , Sato Toshiro , Tetsuhiko Mizoguchi Tetsuhiko Mizoguchi
Published: October 2002

The (112) epitaxial Fe72Co28films with bct symmetry (c/a≤1) were grown on MgO(110) substrates by ion beam sputtering. These films exhibited a low coercive force of 150 A/m in the hard magnetization axis with large saturation magnetization of 2.4 T although the body-centered Fe-Co system has large magnetostriction. These epitaxial films had a uniaxial anisotropy in (112) plane with [111̄] easy axis, and the energy of this in-plane anisotropy depended on the acceleration voltage of the sputtering ion beam gun. The in-plane magnetic anisotropy dependence against the acceleration voltage was discussed in terms of the bct lattice strain effect based on the pseudo-dipolar interaction model.
Direct Charge Leakage through Humid Air
Authors: Tada Yasufusa , Murata Yuji
Published: October 2002

The electric potential of a charged metal ball held in a grounded aluminum spherical shell with a single Teflon fiber is found to decay faster in humid air. Since the resistance of the Teflon fiber measured in air of 96% relative humidity was at least four orders of magnitude larger than the equivalent resistance of humid air between the ball and the shell, it is considered that the potential decay of the ball in humid air is due to the direct leakage of charge into the air.
Heteroepitaxial Growth of Yttria-Stabilized Zirconia Film on Silicon by Reactive Sputtering
Authors: Horita Susumu , Murakawa Masakazu , Fujiyama Takaharu
Published: October 2002

Heteroepitaxial yttria-stabilized zirconia (YSZ) film is difficult to grow on Si by reactive sputtering with Ar+O2 gas, since the bare Si surface is easily oxidized by plasma radiation. In order to overcome this difficulty, the substrate is subjected to weak oxidation and subsequent deposition of a very thin metallic Zr1-
x

Y

x

film prior to deposition of the YSZ film. It was found that the crystalline quality of the YSZ film on Si was further improved by repeating the cycle of weak oxidation and very thin metallic film deposition prior to deposition of the YSZ film. Rutherford backscattering spectrometry indicated a high-quality crystal with a channeling minimum yield of 7.4% for the YSZ film produced by this repetitive method in reactive sputtering.
Computerized Ultrasonic Reflectivity Tomography by Transmitter/Receiver Array Transducers at Circumference Points
Authors: Mitsuo Amagai Mitsuo Amagai , Akira Yamada Akira Yamada
Published: October 2002

Computerized ultrasonic reflection-type tomography provides a means of obtaining the acoustic reflectivity image of an object. In this paper, fixed-array transducer elements are considered with the aim of real-time data acquisition. However, the number of elements is restricted because of space limitation for the transducer arrangement. Thus, streak-like artifact is unavoidably caused by the use of very few observation views. To cope with this problem, correction of streak artifact is employed in the iteration procedure of the algebraic reconstruction technique. The validity of the method using synthesized data for weak scattering cylindrical test objects is investigated. Results show that relatively good images are obtained using a restricted number of fixed transducers.
Surface Temperature Increase in Reactive Ion Beam Etch and Improvement of Profiles by Multistep Etching
Authors: Matsutani Akihiro , Koyama Fumio , Kenichi Iga Kenichi Iga
Published: October 2002

We have carried out an in-situ measurement of temperature variation by a radiation thermometer during Cl2-reactive ion beam etch (RIBE). It is found that the surface temperature of the sample is noticeably increased by the etching with high ion-extraction voltage. The surface temperature was increased by about 250 K under ion irradiation with extraction voltage of 400 V for 15 min. We found that side-etch is caused by the temperature rise of the sample surface due to ion irradiation. We have also proposed a multistep RIBE for improving etched profiles.
Aspect Ratio Independent Etching: Fact or Fantasy?
Authors: III Andrew D. Bailey , Richard A. Gottscho Richard A. Gottscho
Published: October 2002

The scaling of anisotropic plasma etch rates with feature dimensions is an important issue when fabricating microelectronic and photonic devices. For a wide rage of conditions, etch rates are found to scale primarily with the feature depth/width or aspect ratio. Features with large aspect ratios etch more slowly than those with low aspect ratios regardless of feature width. However, in the presence of etch inhibitors, the scaling of etching rates with feature dimensions becomes more complicated. Smaller aspect ratio features may etch more slowly than larger aspect ratio features suggesting that etch-inhibiting chemistry could be exploited in achieving the here-to-fore elusive goal of aspect ratio independent etching (ARIE). Using a well-established etching model, based on Langmuir adsorption kinetics, we derive the etch inhibitor flux and surface adsorption parameters required to achieve ARIE.
Although the required parameters are non-physical when the range of aspect ratios is unconstrained, it is possible to achieve ARIE over a restricted range of aspect ratios. However, the balance required between ion, etchant, and inhibitor fluxes is a fragile one. The best approach to minimizing the variation in etching rate with aspect ratio is to operate a high density plasma at low pressure with high neutral flow rates.
The Electron Charging Effects of Plasma on Notch Profile Defects
Authors: Nozawa Toshihisa , Kinoshita Takashi , Nishizuka Tetsuya , Narai Akira , Inoue Takayoshi , Akimitsu Nakaue Akimitsu Nakaue
Published: October 2002

The notch occurrence factor in polysilicon etching was investigated using a newly designed test mask pattern. This pattern varied the space width, the line width of the line-and-space structure, and the pad perimeter which connected the line-and-space structure. By using this test pattern, it was found that the notch depth increases as the “perimeter ratio”, (i.e. the ratio of the pad perimeter to the notch line perimeter), increases. Moreover, when the perimeter ratio was very small, the notch depth was quite small. Therefore, it is considered that the notch is caused by electron supply from the periphery of the pad which collects the electrons from plasma. As a result of this electron conduction, in the case of the non-connected lines, the notch occurs only outside the line of the line-and-space structure, and in the case of the connected lines, the notch occurs at all of the connected lines. The notch depth difference between the non-connected lines and connected lines is explained by the difference in perimeter ratio.
Reaction Studies between Fluorocarbon Films and Si Using Temperature-Programmed X-Ray Photoelectron and Desorption Spectroscopies
Authors: Hirashita Norio , Miyakawa Yasuhiro , Fujita Ken , Jun Kanamori Jun Kanamori
Published: October 2002

Surface structure of plasma-polymerized fluorocarbon thin film on Si and gas desorption were concurrently studied as a function of temperature between 20 and 700° C using temperature-programmed X-ray photoelectron spectroscopy with a residual gas analyzer. The films, consisting of CF3, CF2, CF and C-CF

x

bonds, with the F/C ratio of 1.7 were found to be stable up to 200° C and to thermally decompose above 200° C. SiF4 desorption, following gradual pyrolysis with decrease in CF3, CF2 and CF bonds due to desorption of fluorocarbon gases, was observed for F/C ratios ranging from 1 to 0.1. The pyrolytic process of the film and the thermal reaction with Si substrates were further discussed based on results of additional desorption and ion-induced reaction experiments.
Hg-Sensitized Photochemical Vapor Deposition Application to Hydrogenated Amorphous Silicon Photoconversion Layer Overlaid on Charge Coupled Device
Authors: Nozaki Hidetoshi , Sakuma Naoshi , Niiyama Takako , Ihara Hisanori , Ishizuka Yoshiki , Ichinose Hideo , Iida Yoshinori , Sasaki Michio , Sohei Manabe Sohei Manabe
Published: October 2002

An Hg-sensitized photochemical vapor deposition method has been developed which has enabled a hydrogenated amorphous silicon photoconversion layer to be overlaid on a charge coupled device (CCD) imager, without a pixel separation structure. This chemical vapor deposition (CVD) method has been used to realize imaging devices with high sensitivity and high resolution for high-definition TV.
Improvement of Thin Oxides Thermally Grown on the Reactive-Ion-Etched Silicon Substrates
Authors: Ueng Shih Yuan , Wang Ping Wei , Kang Tzong Kuei , Chao Tien Sheng , Chen Wen Ho , Dai Bao Tung , Hung Chong Cheng Hung Chong Cheng
Published: October 2002

Thin oxides thermally grown in reactive-ion-etched (RIE) silicon substrates in N2O and diluted O2 ambient have been studied. The microroughness of the oxide-silicon interface was investigated using a spectrophotometer, atomic force microscopy (AFM), and cross-sectional high-resolution electron microscopy (HRTEM). The microroughness is strongly dependent on the RIE conditions and the post etching treatments. Furthermore, oxidation-enhanced interface microroughness has been observed. As compared with the pure oxides grown in diluted oxygen, N2O-grown oxides exhibit stronger immunity to RIE-induced damage. N2O oxidation of the etched specimens treated with an after-treatment-chamber (ATC) process result in the best electrical properties.
YBa2Cu3Ox Thin Films with Yttria Stabilized Zirconia Buffer Layer on Metal Substrate by Liquid Source Chemical Vapor Deposition Using Tetrahydrofuran Solution of β-Diketonates
Authors: Matsuno Shigeru , Umemura Toshio , Uchikawa Fusaoki , Ikeda Bunko
Published: October 2002

Textured YBa2Cu3O

x

(YBCO) thin films with c-axis orientation on Ni-based metal substrate with yttria stabilized zirconia (YSZ) and Pt buffer layers were formed by liquid source chemical vapor deposition (LS-CVD) using tetrahydrofuran (THF) solution of β-diketonates. The YSZ buffer layer with a-axis orientation was formed by the similar LS-CVD on prebuffer layers of amorphous YSZ and Pt deposited by sputtering at room temperature. The CVD-YSZ buffer layer was mechanically polished before the deposition of YBCO.
By transmission electron microscopy (TEM) and analytical electron microscopy (AEM), it was ascertained that YBCO and YSZ layers had platelike and column-shaped grains, respectively. An intermetallic compound of the Pt-Ni-Cr system was produced in the vicinity between the YSZ layer and metal substrate. The critical temperature (T
c) of 91 K and the transport critical current densities (J
c) of 1.4×105 A/cm2 at 77 K, zero field, and 2.0×104 A/cm2 at 1.5 T were achieved.
Microstructures of Co/Cr Bilayer Films Epitaxially Grown on MgO Single-Crystal Substrates
Authors: Nakamura Atsushi , Koguchi Masanari , Masaaki Futamoto Masaaki Futamoto
Published: October 2002

Microstructures of Co/Cr bilayer films epitaxially grown on MgO (100) and (110) single-crystal substrates have been studied by high-resolution transmission electron microscopy. The bicrystalline Co layer formed on the MgO (100) substrate contains a number of (0001) stacking faults. The single-crystal Co layer formed on the MgO (110) substrate consists of slightly misoriented subgrains, grown on (211)-oriented Cr domains. Dislocations and lattice strain are observed at the Cr/MgO (110) interface. The misorientations and the defects are thought to be introduced to accommodate the large lattice mismatch of about -16% in the MgO [1̄10] direction at the Cr/MgO (110) interface.
Relationship between Molecular Structure and Temperature Dependence of Threshold Voltage in Fluorinated Liquid Crystals
Authors: Nishi Tetsuo , Matsubara Akifumi , Okada Hiroyuki , Onnagawa Hiroyoshi , Sugimori Sigeru , Miyashita Kazuo
Published: October 2002

We evaluate the temperature dependence of threshold voltage and physical constants (anisotropy of dielectric constants and elastic constants) by using fluorinated phenylbicyclohexane liquid crystal compounds. It is found that the positions of fluorine substituents influence the dielectric constant and its temperature dependence. A systematic relationship between the fluorine substituents and physical constants was obtained.
Atomic Hydrogen-Assisted GaAs Molecular Beam Epitaxy
Authors: Okada Yoshitaka , Sugaya Takeyoshi , Ohta Shigeru , Fujita Tomoya , Mitsuo Kawabe Mitsuo Kawabe
Published: October 2002

A continual irradiation of atomic H during the growth of GaAs in molecular beam epitaxy (MBE) has been shown to be a viable method to obtain sharp heterointerfaces and high-quality epitaxial layers. We provide some fundamentally important observations related to atomic scale mechanisms and interactions, and the growth models for atomic H-assisted homoepitaxial GaAs MBE are proposed. Atomic H has been shown to be an efficient surfactant reducing the surface and total energy of GaAs(100) that acts to promote layer-by-layer and step-flow growth mode. However, the actual growth kinetics is different depending on the growth temperature, which affects the energetic stability of atomic H adsorption on GaAs(100). Furthermore, the continual removal of surface contaminants and also the excess arsenic during the growth are thought to be another important attribute played by atomic H.
Depolarization Characteristics in Sol-Gel Ferroelectric Pb(Zr0.4Ti0.6)O3 Thin-Film Capacitors
Authors: Mihara Takashi , Yoshimori Hiroyuki , Watanabe Hitoshi , Araujo Carlos A. Paz de
Published: October 2002

Studies of depolarization characteristics have been carried out on so-gel lead zirconate titanate (PZT) ferroelectric thin-film capacitors by electrical evaluation of the pulse switching response employing a capacitor-loaded circuit. Four consecutive positive pulses were used to evaluate the depolarization effect after negative writing, instead of conventional positive and negative double pulses. The extended evaluations were carried out for, e.g., pulse height, pulse width, temperature dependence, and space charge effect. The amount of depolarization strongly depended only upon the value of load capacitance. The transition and hysteresis loops from pulse switching clearly showed that the depolarization occurred due to the depoling (partial switching) of domains by an opposite-directional depolarization field which arose from accumulated switched charge on the load capacitor. We considered that depolarization occurs as a result of both external depolarization field from an external load capacitor and internal depolarization field from interfacial layers within ferroelectric material.
Analytical Simulation of Electrooptical Performance of Multidomain Twisted Nematic Liquid Crystal Displays
Authors: Sugiyama Takashi , Hashimoto Toru , Katoh Kazuhisa , Iimura Yasufumi , Kobayashi Shunsuke
Published: October 2002

The electrooptical characteristics of multidomain twisted nematic liquid crystal displays (TN-LCDs), such as optical properties, contrast ratio contours, and gray-scale performance, have been investigated by a computer simulation, where the number of domains of each pixel is chosen as 1, 2, 4, 8, 16, 32, 64, and 120 with the aim of determining the optimum number of domains. It is shown that the TN-LCD with quartered pixels exhibits the best results in terms of the viewing angle and gray-scale performance, and furthermore, that more than eight domains gives the same result as for the amorphous TN-LCD that has several thousand domains in each pixel.
Focal Conics in Chiral Smectic C Liquid Crystals. II
Authors: Nobuhiko Nawa Nobuhiko Nawa
Published: October 2002

By means of a polarizing microscope, the structural change of the focal conics is investigated in the chiral smectic C phase. It is found that the parabolic focal conics change to the ellipse-hyperbola type at the critical temperature which is related to the critical layer tilt angle of the chevron structure.
Effect of Plasma-Cathode Method on Production of Highly Charged Ions from Oxide in RIKEN 10-GHz Electron-Cyclotron-Resonance Ion Source
Authors: Nakagawa Takahide , Kageyama Tadashi , Kase Masayuki , Goto Akira , Yasushige Yano Yasushige Yano
Published: October 2002

The plasma-cathode method was characterized for producing highly charged Al, Mg, Si, Ti, Co, Ni, and Zr ions from the respective oxides in the RIKEN 10-GHz electron-cyclotron-resonance ion source. As a result, this method was found to be considerably effective in enhancing their beam intensities.
Influence of Impurities on Surface Recombination of Nitrogen Atoms in Late Afterglow
Authors: Marković Vidosav Lj. , Petrović Zoran Lj. , Pejović Momčilo M.
Published: October 2002

The influence of impurity contents (water vapour and oxygen) on surface recombination of nitrogen atoms on the glass walls and the copper electrode surface is studied. The decay of nitrogen atom number density in late afterglow has been detected by the breakdown time delay method and the memory effect was found for nitrogen with large abundance of impurities (technical purity gas). The dominant reaction on the glass walls covered with water vapour was found to be of the second order. The surface recombination coefficient has been increased by about two orders of magnitude compared to the pure gas. Also, the increase of the secondary electron yield by about one order of magnitude occurs caused by chemisorbed oxygen on the electrode surface.
Squeezing of a Focused Acoustic Beam and Acoustic Microscopy of Anisotropic Media
Authors: Tsutomu Hoshimiya Tsutomu Hoshimiya
Published: October 2002

The concept of squeezing in quantum optics is applied to focused acoustic beam evaluation for the first time. Mathematical equivalence between coherent and squeezed states in quantum optics and angular spectra in various acoustical imaging schemes is derived and discussed. The squeezing operation, which deforms or controls pairs of physical quantities, is defined to evaluate focused acoustic beam quality from a unified point of view, especially in the measurement of anisotropic materials. Furthermore, the concept of the “vector figure of merit” is introduced, which describes both the resolution of focusing and the ability to measure the anisotropy of materials.
Relaxations of Fragile Liquid by Combination of Brillouin to Raman Scattering Spectra
Authors: Kojima Seiji , Takanashi Katsutoshi , Yoshihara Akira
Published: October 2002

The broadband light scattering spectra of glycerol were measured using both the Sandercook-type 3+3 pass vernier tandem Fabry-Perot interferometer and the triple-grating additive spectrometer. The depolarized spectrum at 363 K clearly shows an α peak and a boson peak. The lineshape of spectra was analyzed by the mode coupling theory and from the phenomenology including an α relaxation of Davidson-Cole type and a boson peak of the disorder-induced model. In the polarized spectra, strong coupling between longitudinal acoustic phonon and the fast relaxation process was observed. It is found that the relaxation frequency obtained from the Brillouin components is much higher than that of α relaxation, and its temperature dependence is weaker than that of α relaxation frequency. This strongly suggests that acoustic phonons couple not to the α but the another fast relaxation process.
Elastic Variations of Paraffin Wax during Solid-Liquid Phase Transition
Authors: Hiroaki Kamioka Hiroaki Kamioka
Published: October 2002

The shear wave velocity and the attenuation of ultrasonic waves in paraffin wax, which is a mixture of many paraffin hydrocarbons, were measured at 1 MHz using the pulse transmission method in the temperature range from 10 to 80° C exceeding the melting temperature of 44-46° C. By combining the present experimental data with our previous data on compressional wave velocity, the elastic properties of paraffin wax during melting and solidification were derived. Markedly high adiabatic compressibility during melting and solidification was obtained in the melting temperature region.
Velocity of Sound and Elastic Properties of Li2O-B2O3 Glasses
Authors: Kodama Masao , Matsushita Toru , Kojima Seiji
Published: October 2002

Ultrasonic velocity in glasses denoted by the composition formula x
2 Li2 O·(1-x
2) B2 O3 (x
2 is the mole fraction) is measured over the composition range 0≤x
2≤0.28 at 10 MHz and 298 K by the ultrasonic pulse-echo overlap method. The elastic property of the glasses is analyzed in terms of the three structural units defined as BØ3≡
a
, Li+BØ2O-≡
b
and Li+BØ-
4≡
c
, where Ø represents a bridging oxygen and O- a nonbridging oxygen, on the assumption that these have their respective elastic constants defined on the basis of the elastic internal energy due to deformation. It is shown in particular that the structural unit a is converted only into the structural unit c by the reaction 2BØ3+Li2O→2Li+BØ-
4 in the composition range 0≤x
2≤0.28.
Degradation of Piezoelectric Properties at Resonant Operational Mode by a Large Input Power
Authors: Yamamoto Takashi , Fumio Mizuno Fumio Mizuno
Published: October 2002

Piezoelectric properties at resonant operational mode were measured after applying a large input power and are discussed from the viewpoint of heat generation. The heat generation by a large input power was yielded from both mechanical vibration and dielectric losses. Below 50° C, mechanical vibration and dielectric losses were larger in low-Q

m
than high-Q

m
materials; therefore heat generation became larger in low-Q

m
material. The pulsed input power could suppress the heat generation, resulting in the decrease of degradation in piezoelectric properties.
Study on Surface Acoustic Wave Devices for a Pulse Position Modulated Direct Sequence Spread Spectrum Communication System
Authors: Hohkawa Kohji , Araki Nobushige , Komine Kenji , Hara Motoaki , Hiroki Ueno Hiroki Ueno
Published: October 2002

This paper demonstrates a modulation method for a spread spectrum communication system in which a relatively large pulse compression ratio is usable for a narrow transmission bandwidth employing specially designed surface acoustic wave devices. We present the circuit configuration and discuss merits, performance, and drawbacks of the system. We also describe a basic experiment on the SAW device which verifies the feasibility of the system.
Enhancement in Diffusion of Electrolyte through Membrane Using Ultrasonic Dialysis Equipment with Plane Membrane
Authors: Li Hui , Ohdaira Etsuzo , Masao Ide Masao Ide
Published: October 2002

Application of ultrasound to accelerate the dialysis separation of electrolytes through a membrane was studied with ultrasonic dialysis equipment. The experiments were conducted with cellophane membrane and KCl solution, CH3COONa solution, and a mixture of KCl and saponin solutions. It was found that the diffusion velocity of electrolyte through a membrane with ultrasonic irradiation is faster than that without ultrasonic irradiation, and it increases with acoustic pressure. It has become clear that the reasons for enhancement caused by ultrasound are increase in liquid particle velocity and diffusion coefficient due to ultrasonic vibration. It was confirmed that the permeability of the membrane was not degraded by ultrasound in the ranges of acoustic pressure and irradiation time in this study.
A Study on the Mechanism of a Scientific Toy “Girigiri-Garigari”
Authors: Satonobu Jun , Ueha Sadayuki , Nakamura Kentaro
Published: October 2002

“Girigiri-Garigari” is the Japanese name of a scientific toy which consists of a square rod and a propeller. The wooden rod has several notches along its long edge, and the propeller is loosely attached to one end of the rod by a nail. The propeller is rotated by rubbing the rod with another bar. A player can control the revolution direction of the propeller in two ways, by changing the gripping position or condition of the rod. This paper presents an experimental study on the mechanism of this toy. Main results of this study are that the revolution of the propeller is caused by the elliptical motion excited at the end of the rod, and that the vibration system can be represented by a lumped-constants model. Then, we reveal the mechanism of how the elliptical motion is generated by the player's operations.
Multilayer Piezoelectric Motor Using the First Longitudinal and the Second Bending Vibrations
Authors: Saigoh Hiroaki , Kawasaki Mayumi , Maruko Nobuhiro , Kouichi Kanayama Kouichi Kanayama
Published: October 2002

A piezoelectric linear motor using a double-mode vibrator was constructed with one of the vibration modes being the first longitudinal and the other, the second bending. In order to reduce driving voltage, a multilayer piezoelectric ceramics vibrator prepared by a cofiring method was used. Moreover, we proposed a new type of supportive mount for the vibrator to facilitate the construction of the motor. In the new method the vibrator is bonded to an attachment plate by an elastic layer. In this paper, characteristics of the motor are described.
Visualization and Analysis of Myocardial Transition by Cardiac Ultrasound Images
Authors: Amamoto Naohiro , Oshiro Osamu , Kosuke Sato Kosuke Sato , Kunihiro Chihara Kunihiro Chihara
Published: October 2002

In this paper we present a technique for visualization and analysis of cardiac wall motion, i.e., myocardial transition abnormalities, by digital cardiac ultrasound B-mode images. This technique is based on the correspondence analysis of characteristic points, called landmarks, extracted from endocardial boundary locations and can be used for wall motion analysis of the heart. The algorithm for this technique is that first, cardiac images are segmented into the myocardium and the background image using the gradient relaxation method and endocardial boundary locations are extracted. Next, the landmarks with geometric features are specified, and correspondence analysis is performed with landmarks of the next image. Functional diagnosis of moving organs can be performed by classifying the endocardial boundary into some appropriate colors and superimposing on the original B-mode image.
Intravascular Ultrasonic Imaging with a Micromotor
Authors: Seiji Matsumoto Seiji Matsumoto , Osamu Oshiro Osamu Oshiro , Kunihiro Chihara Kunihiro Chihara , Atsuo Iida Atsuo Iida , Kenji Kawabe Kenji Kawabe , Takaki Shimura Takaki Shimura , Masato Asao Masato Asao , Toshiyuki Furukawa Toshiyuki Furukawa
Published: October 2002

This paper reports a new intravascular imaging system with a micromotor, revolution characteristics of the micromotor and experimental results using a plastic tube. In this system, an ultrasonic beam is scanned radially by the micromotor instead of a scanning wire. The experimental results show that a cross-sectional image of the tube is reconstructed and that this system has a possibility of application to the observation of the inside of a blood vessel.
Generation and Directivity Control of Bulk Acoustic Waves by Phase Velocity Scanning of Laser Interference Fringes
Authors: Nishino Hideo , Tsukahara Yusuke , Cho Hideo , Nagata Yoshihiko , Koda Toshio , Yamanaka Kazushi
Published: October 2002

A novel method for generating high-frequency bulk acoustic waves (BAW) using scanning interference fringes (SIF) is presented. The SIF are produced by intersecting two coherent laser beams with different frequencies on an opaque specimen. It is possible to generate unidirectional BAW which propagate into the specimen by this method. Propagation direction of the BAW is determined by the phase-matching condition between the SIF and the wave front of the BAW at the surface, which could be controlled by incident angles of laser beams. The principle of this method and experimental verification using a sintered Si3N4 specimen are described. Experiments were carried out using a 15 mJ/130 ns Q-switched Nd:YAG laser for 80 MHz BAW generation and optical knife-edge method with 50 mW argon-ion CW laser for detection. Directivity of BAW was steered from 24.5° to 77.5° by changing the incident angles of the laser beams from 0.066° to 0.136°. BAW were found to be well collimated especially in the near field.
Acoustical Imaging Using a Leaky Wave Transducer Composed of a Piezoelectric Ceramic Plate and an Acryl Plate
Authors: Toda Kohji , Kenji Motegi Kenji Motegi
Published: October 2002

An interdigital transducer (IDT) for leaky waves in a layered substrate composed of a piezoelectric ceramic thin plate and an acryl plate is incorporated into a C-mode acoustical imaging system. The transducer performance in the layered structure is described from the viewpoint of ultrasound radiation at an interface between an acryl plate and a water layer. The leaky wave transducer has frequency-dependent radiation angles, corresponding to the leaky wave velocity, under multiple operation modes. The bulk wave direction in a test sample via the longitudinal wave in the water layer is easily controlled by frequency change. A reflection type C-mode acoustical imaging system is successfully demonstrated for nondestructive testing.
Theoretical and Experimental Studies of Photothermal Dielectric Spectroscopic Microscope
Authors: Yasuo Cho Yasuo Cho , Tomoyuki Kumamaru Tomoyuki Kumamaru
Published: October 2002

A new photothermal technique is proposed. This is based on the temperature characteristic of the dielectric constant of light-irradiated material. When a dielectric material is illuminated with chopped light, alternating variation of capacitance is caused by the heat produced due to light absorption, and this variation is detectable with sufficient dynamic range and sensitivity. First, quantitative derivations are presented for the alternating capacitance variation in terms of the optical, thermal, dielectric and geometric parameters of the system. Next, some fundamental experiments on the photothermal dielectric spectroscopic microscope (PTDSM) to confirm the validity of this theoretically predicted photothermal dielectric signal are performed, and it is shown that the observed signals agree with the theoretical ones very well. Finally, a highly sensitive PTDSM using the coaxial cavity resonator with operating frequency of microwave range is developed. Using this microscope, the temperature characteristics of the dielectric materials for microwave application are successfully measured.
Photo-Elastic Constants of Proton-Exchanged LiNbO 3
Authors: Shoji Kakio Shoji Kakio , Yasuhiko Nakagawa Yasuhiko Nakagawa
Published: October 2002

The acousto optic interaction on proton-exchanged 128°-rotated Y-cut LiNbO3 was investigated to evaluate the photo-elastic constants. The experimental and theoretical analysis using a surface acoustic wave of 200 MHz and a He-Ne laser beam showed that the acoustic power required for 100% diffraction depends on the proton-exchange depth and that the photo-elastic constants of the proton-exchanged layer are 76% of those in unexchanged LiNbO3. The effects of annealing on the photo-elastic constants and the diffraction efficiency were also measured.
Finite Bandwidth Effects on Raman Backscattering in Inhomogeneous Plasma
Authors: Laham Nabil M. , Khateeb Ahmed M. , Ayoub Nabil Y. , Abdallah Asad K. , Odeh Isam M. , Munir S. Dababneh Munir S. Dababneh
Published: October 2002

The effect of bandwidth on Raman backscattering is investigated and an expression for convective amplification is derived, where the effects of collision and phase mismatch were taken into consideration. We found that if we neglect the collision frequency, the dependence of the amplification factor on the bandwidth disappears. The growth rate was also investigated and it was found to decrease with bandwidth. We obtained a formula to estimate the threshold intensity of the pump wave.
Long-Term Instability of Lithium-Drifted Silicon Detector
Authors: Miyachi Takashi , Matsuzawa Hidemi , Otogawa Takao , Kobayashi Norihiro , Onabe Hideaki
Published: October 2002

Using 1150 nm infrared light, the change in the detector sensitivity was studied. As a simple measure of the states of the detector sensitivity, the time derivative of the photocurrent is proposed. In terms of the derivative, the change is uniquely classified into two categories. Even after the detector is aged, the derivative does not remain constant with respect to time and voltage. The physical mechanisms which cause the change are discussed based on possible effects due to unstable surface states and the accumulation of an oxide layer.
Acoustic Properties of Lens Materials for Ultrasonic Probes
Authors: Fujii Hideji , Nakaya Chitose , Takeuchi Hiroshi , Kondo Toshio , Ishikawa Yasuo
Published: October 2002

The acoustic velocities and densities of 20 types of commercial rubber have been measured at a frequency of 2 MHz at room temperature, and they are evaluated in terms of their application to an acoustic lens or an acoustic window of probes of an ultrasonic diagnostic instrument. Fluorosilicone rubber and phoshazene rubber have lower acoustic velocities than the human body, and they have excellent impedance matching with the human body. Both the acoustic velocities and densities of butadiene rubber, polybutadiene rubber, acrylic rubber and polyurethane match those of the human body. It is also described that rubber having good impedance matching with the human body can be fabricated by adjusting the volume fraction of the added filler.
Monte Carlo Simulation of Ion Bombardment at Low Glancing Angles
Authors: Tohru Ishitani Tohru Ishitani
Published: October 2002

Monte Carlo simulations were applied to the incident ion trajectories for coarse viewing of ion-target interaction in the finishing stage of focused ion beam (FIB) cross sectioning, i.e., typically, 30 keV Ga ion bombardment of Si and W targets at low glancing angle β. Basic physical parameters of backscattering yield, energy distribution and deposited energy of the backscattered ions, and ion depth distribution are obtained as functions of β. The backscattering yields sharply increase toward 1 with decrease of β to 0, especially for a W target. The energy distributions of backscattered ions reflect the ion deceleration behavior near the surface. Such behavior is consistent with that indicated by the results of ion depth distributions. Basic properties such as ion depth, damage depth, Ga concentration, and the cross-sectional tilt angle of the FIB-milled cross sections are discussed using the basic physical parameters mentioned above.
Scanning Tunneling Microscope Observation of the Metal-Adsorbed Layered Semiconductor Surfaces
Authors: Hideki Abe Hideki Abe , Kotaro Kataoka Kotaro Kataoka , Keiji Ueno Keiji Ueno , Atsushi Koma Atsushi Koma
Published: October 2002

Two metal elements, Sn and Na, have been deposited onto layered semiconductor MoS2(0001) surfaces and observed with a scanning tunneling microscope. The metal-adsorbed area shows a very large dark spot (3–5nm diameter) when the sample bias is positive, and the atomic image of the MoS2substrate can be clearly seen inside the dark area. The same area, on the other hand, shows a bright horseshoe-shaped spot when the sample bias is negative.
Analysis of Heat-Treated 6H-SiC(0001) Surface Using Scanning Tunneling Microscopy
Authors: Yoshitomo Marumoto Yoshitomo Marumoto , Takeshi Tsukamoto Takeshi Tsukamoto , Masaaki Hirai Masaaki Hirai , Masahiko Kusaka Masahiko Kusaka , Motohiro Iwami Motohiro Iwami , Takehiro Ozawa Takehiro Ozawa , Toshihiko Nagamura Toshihiko Nagamura , Toshitake Nakata Toshitake Nakata
Published: October 2002

A scanning tunneling microscopy in ultrahigh vacuum (UHV) has been used to study hexagonal (6H) silicon carbide (0001)Si face prepared by heat treatment. √3 ×√3, 6 ×6 and 3 ×3 reconstructions were observed above 1100°C.
With increasing heat-treatment temperature, surface structure changed drastically and step heights decreased to that of a double layer. The 6 ×6 and 3 ×3 reconstructions can be explained as the structure of a graphite layer on the SiC surface and as the structure proposed by Kaplan, respectively.
Molecular Arrangements of Fatty Acids and Cholesterol at Liquid/Graphite Interface Observed by Scanning Tunneling Microscopy
Authors: Masahiro Hibino Masahiro Hibino , Akinori Sumi Akinori Sumi , Ichiro Hatta Ichiro Hatta
Published: October 2002

We have directly imaged organic molecules such as fatty acids and cholesterol adsorbed onto a graphite substrate using a scanning tunneling microscope (STM). The arrangements of pure fatty acids such as myristic, palmitic, stearic, arachidic, behenic and elaidic acids are essentially similar except that STM images change systematically with the length of the alkyl chain. The STM images attained atomic resolution and as a result we observed the individual hydrocarbon groups in the alkyl chains. In the direction parallel and perpendicular to the molecular axis, the molecules on the graphite substrate form dimers via hydrogen bonding between carboxyl groups and a superstructure with a period of four or five molecules, respectively. The image of a monolayer of a binary mixture of fatty acids adsorbed onto the substrate reflects two different lengths of alkyl chains. A monolayer of cholesterol molecules was imaged for the first time.
Nanometer Modifications of Non-Conductive Materials Using Resist-Films by Atomic Force Microscopy
Authors: Shin-ichi Yamamoto Shin-ichi Yamamoto , Hirofumi Yamada Hirofumi Yamada , Hiroshi Tokumoto Hiroshi Tokumoto
Published: October 2002

We demonstrate the nanolithography of a SiO2 substrate by modification of ultrathin films of nonconducting polymer using an atomic force microscope (AFM) followed by wet etching. Using an AFM tip under high normal forces of the order of 100 nN in air, and at a writing speed of 1 µm/s, large areas of 10 ×10 µm2 patterns with widths less than 28 nm and depths of 10 nm were reliably fabricated onto the SiO2 substrate.
Effects of High-Temperature Annealing on the Structural and Crystalline Qualities of GaAs Heteroepitaxial Layers Grown on Si Substrates Using Two-Step and Direct Methods by Molecular-Beam Epitaxy
Authors: Yodo Tokuo , Masao Tamura Masao Tamura
Published: October 2002

The structural and crystalline qualities of GaAs/Si heteroepitaxial layers (heteroepilayers) were remarkably improved by annealing at temperatures above 900° C, independently of the growth methods, either two-step or direct. The effects of high-temperature annealing on the optical property, residual strain, and the relation of the improvement in the quality with the out-diffusion of Si from the substrates and with vacancies in the GaAs heteroepilayers have been systematically investigated by a series of measurements using photoluminescence spectroscopy, secondary-electron microscopy, double-crystal X-ray diffraction, secondary-ion mass spectroscopy and cross-sectional transmission electron microscopy.
The Effect of Total Reactor Pressure on GaInSb Grown on Gd3Ga5O12 Substrate by Metal Organic Chemical Vapor Deposition
Authors: Totoki Machiko , Mizumoto Tetsuya , Nakamura Toshihiko , Maru Kouichi , Sato Yoshiyasu , Yoshiyuki Naito Yoshiyuki Naito
Published: October 2002

To investigate the possibility of improving the crystal quality of a GaInSb layer grown on a Gd3Ga5O12 substrate by metal organic chemical vapor deposition (MOCVD), experimental studies were carried out on the effect of the total reactor pressure. The lattice constant was affected by the pressure. The effect of reducing the pressure was dependent on the growth temperature. In a low-temperature regime, the lattice constant increased, and at high temperature it decreased, as the pressure was reduced. The growth rate increased as the pressure was reduced in both temperature regimes. Upon reduction of the pressure, the range of growth conditions which gives a preferentially (111)-oriented GaInSb layer became narrow.