bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Polarographic Oxygen Sensor Using the Pores of the Pt Cathode as a Gas Diffusion Barrier
Authors: Usui Toshio , Yamamoto Hideo , Ishibashi Kohsei , Nakazawa Mitsuhiro
Published: February 2005

A gas polarographic oxygen sensor using the pores of the Pt cathode as an oxygen diffusion barrier has been investigated in O2–N2 gas mixtures at 600°C. As expected, the pores of the cathode functioned as a gas diffusion barrier restricting the access of gaseous oxygen to the interface of the Pt cathode and a zirconia electrolyte; consequently, the limiting current was realized. The resulting current increased linearly with the oxygen concentration in the range of 3–25% in the ambient atmosphere when the voltage applied to the cell was held constant within a range of 0.6–2.4 V. In addition, the output current of the sensor was interpreted to be a mixed current of both an ohmic current proportional to the applied voltage and a current based on the diffusion restriction of gaseous oxygen.
Zn Diffusion in In1-xGaxP
Authors: Kim Seon Tai , Moon Dong Chan
Published: February 2005

The properties of Zn diffusion in the III-V ternary alloy semiconductor In1-x
Ga
x
P have been investigated. The Zn diffusion depth changed in proportion to the square root of diffusion time and decreased with composition of In1-x
Ga
x
P. The effective diffusion constant at a given temperature was decreased with composition, while the activation energy for Zn diffusion was increased, due to a lower contribution of the interstitial diffusion with increasing Ga atom content in In1-x
Ga
x
P
Electrical and Optical Properties of CuInS2 Grown by the Sintering Method
Authors: Yamamoto Nobuyuki , Ogihara Jyun , Horinaka Hiromichi
Published: February 2005

Electrical and optical properties as well as achieved density are studied for highly densified and oriented CuInS2 crystal-like tablets prepared by the sintering method. The stoichiometric single-crystal fragment grown at 1050°C is found to have the best electrical quality with resistivity of 50 Ωcm. Deviation from stoichiometry results in p-type and n-type conduction for Cu2S-rich and In2S3-rich crystals, respectively.
The Enhancement of Tc in Calcium Free Tl-Bilayer Superconducting System (Tl2Ba2Cu1Ox)
Authors: Saini K. K. , Sharma C. P. , Ekbote S. N. , Asthana Pavas , Suri D. K. , Agnihotry Chanderkant , Chandra Subhas
Published: February 2005

The observation of enhanced T
c in calcium free Tl compounds Tl2Ba2Cu1O
x
(2201) with varying concentration of Tl and Cu has been reported. Three different starting compositions (2201, 1201 and 2202) were studied extensively with varying conditions of preparation. Under the optimised conditions: sintering temperature 970°C and duration 3–10 minutes the highest T
c (onset) ∼115 K and T
c (zero) ∼95 K was found. The XRD studies showed the transformation of all the three nominal compositions into 2201 phase with different T
cs.
Synthesis and Magnetic Properties of Fe7C3 Particles with High Saturation Magnetization
Authors: Tajima Shin , Hirano Shin-ichi
Published: February 2005

The formation behavior and magnetic properties of Fe7C3 particles were investigated under atmospheric pressure. The starting material of barium-containing iron oxide was carbureted with CO by heat treatment. Fe7C3 particles were formed in the reaction temperature range of 300–375°C along with a small amount of Fe5C2 particles. Fe7C3 content in the product increased with the increase in the partial pressure of CO and the decrease in the reaction temperature. DTA-TG analysis revealed that the product contained about 5–10 wt% free carbon. The saturation magnetization of the product was about 110 emu/g regardless of the reaction conditions. The coercivity and the ratio of the residual magnetization to the saturation magnetization increased with the increase of the Fe7C3 content in the product.
Hot-Pressed BN–AlN Ceramic Composites of High Thermal Conductivity
Authors: Kanai Takao , Tanemoto Kei , Kubo Hiroshi
Published: February 2005

Hexagonal boron nitride-aluminum nitride (75–25 wt%) ceramic composites are synthesized by uniaxial hot pressing. High thermal conductivity, 247 W/(m·K), is attained for the perpendicular direction of the hot-pressing axis of the sintered body, by optimizing the amount of added sintering aid, calcium carbide. The composites have remarkable anisotropy with respect to structure and thermal conductivity. The revelation mechanism of high thermal conductivity is discussed.
Low-Temperature Thermal Expansion of Silicon
Authors: Sugino Ken-ichi , Okazaki Atsushi
Published: February 2005

In connection with the results of high-resolution X-ray diffraction, thermal expansion of single-crystal specimens of silicon has been measured in the temperature range of 90–300 K at intervals of 1 K. The experiment is based on a new method, the dual-capacitance technique, which independently detects the movement of the top and bottom surfaces of a specimen; a change in the length perpendicular to the surface planes can therefore be determined reproducibly and accurately. Measurements are made of a few specimens in the crystallographic directions [111], [110] and [100]; the results for heating and cooling show no appreciable difference in any case.
Molecular Orientation in Mixed Monolayers of Hemicyanine and Fatty Acid at an Air/Water Interface Studied by Second Harmonic Generation
Authors: Shirota Koichiro , Kajikawa Koutaro , Takezoe Hideo , Fukuda Atsuo
Published: February 2005

The molecular orientation of mixed monolayers consisting of hemicyanine dye and arachidic acid at an air/water interface is studied by optical second harmonic generation. It was found that the average molecular tilt angle with respect to the surface normal is almost unchanged throughout the compression process, and is smaller in a monolayer containing a higher fraction of hemicyanine. The effective local field factor was also evaluated as a function of surface number density and was found to agree qualitatively with the theoretical prediction.
Dependence of Poly(3-alkylthiophene) Film Properties on Electrochemical Polymerization Conditions and Alkyl Chain Length
Authors: Wang Shenglong , Takahashi Hiroyuki , Yoshino Katsumi , Tanaka Kazuyoshi , Yamabe Tokio
Published: February 2005

Conductivity of the poly(3-alkylthiophene) (PAT) films is strongly affected by the conditions of electrochemical polymerization. The oxidation potential is higher and the conductivities lower in the PAT films of longer alkyl chain length. On the other hand, ΔH
pp is narrower and the spin concentration higher in the PAT films of shorter alkyl chain length.
Dependence of ECR Plasma Etching Characteristics on Sub Magnetic Field and Substrate Position
Authors: Samukawa Seiji , Mori Sumio , Sasaki Masami
Published: February 2005

By using an ECR plasma etching system equipped with a sub magnetic coil, the dependences of etching characteristics on sub magnetic field and substrate position of polyimide film etching are investigated. A bowing-free etching profile, etching rate of more than 1 µm/min, and etching rate uniformity of ±5% on a 6 inches diameter substrate are achieved at the ECR position under O2/SF6 etching gas pressure of 5×10-4 Torr. Etching characteristics at the ECR position are explained by collimated ions, extremely high ion current density and uniform ion current compared with the off-ECR position.
Growth Mechanism of ZnO Film by Reactive Sputtering Method –Significance of Thermodynamics in a Plasma System–
Authors: Tsuji Naoto , Komiyama Hiroshi , Tanaka Kazunobu
Published: February 2005

Zinc oxide films are prepared on a glass substrate by sputtering a zinc target in the rf glow discharge plasma of an argon/oxygen mixture. Growth rate, crystallographic structure, optical absorption, and the electrical conductivity of the films prepared are correlated experimentally with the conditions of the film growth process. The escape rate of zinc atoms from the growing surface, which depends solely on temperature, predominantly affects the chemical composition of the prepared film which includes Zn/ZnO mixture, Zn1+x
O, and ZnO. The role of thermodynamic equilibrium in a glow discharge plasma system that is likely to be far from equilibrium and is kinetically controlled is pointed out for the first time.
The Influence of Al+++ Substitution for Fe+++ in M-Type Ba Ferrite Powder on the Intrinsic Coercivity HcJ
Authors: Zheng Zheng , Zong-Yu Zong-Yu , Feng Feng , Jie Jie , Mei Mei , Xue-Ming Xue-Ming , Guo Guo , Bi-Jun Bi-Jun , Zhang Zhang , You-Gang You-Gang
Published: February 2005

The influence of Al+++ Substitution for Fe+++ in M-type Ba ferrite on the magnetocrystalline anisotropy field H
A and the critical single-domain radius R
c has been studied by Haneda and Kojima. It is difficult to obtain H
cJ values agreeing with theoretical results for the reason that the H
cJ is very sensitive to the preparation method. We have been developing a new method called “coprecipitation combined with high-temperature melting.” It offers a suitable condition for studying the rule of H
cJ of Ba Fe12-x
Al
x
O19. Our results conformed to the effects calculated by Haneda and Kojima. The highest level of H
cJ in our experiment reached 16000 Oe. We have fabricated plastic sheet magnets from the superhigh H
cJ ferrite powder and padded the soft ferrite core with this sheet magnet to adjust the bias magnetic field. This ferrite core can be improved and the weight and size of the device can be reduced.
Magnetic Properties and Microstructures of Fe-Polyethylene Co-Evaporated Films
Authors: Maro Tsuyoshi , Kitakami Osamu , Fujiwara Hideo
Published: February 2005

The magnetic properties, the microstructures and the chemical binding state of carbon atoms of Fe-polyethylene films prepared by co-evaporating Fe and polyethylene were investigated. Magnetic property measurements revealed that the dependence of the saturation magnetization of Fe-polyethylene films on the carbon content was different from that of sputtered Fe–C films, and that Fe-polyethylene films with the carbon content of 11–13 at.% exhibited good soft magnetic properties. The magnetic properties of the Fe-polyethylene film with the carbon content of 11 at.% were as follows; M
s=1390 emu/cm3, H
c=2 Oe, µ=2000 (at 1 MHz), µ=900 (at 10 MHz). The temperature dependence of M
s and H
c indicated that the crystallization temperature was about 240–260°C. The results of XPS showed that most carbon atoms in the Fe-polyethylene films chemically combined with Fe atoms.
Frequency Modulation Method for a He–Ne Laser Using the Mechanical Resonance of the Laser Cavity
Authors: Mio Norikatsu , Tsubono Kimio
Published: February 2005

We developed a method for modulating the frequency of an internal-mirror He–Ne laser (λ=633 nm) by means of the mechanical resonance of the laser cavity. The servo system for frequency control using this method is also demonstrated.
Stress-Optical Coefficients in Polycarbonates
Authors: Shirouzu Shigenori , Shikuma Haruo , Senda Norio , Yoshida Masahiro , Sakamoto Shuji , Shigematsu Kazuyoshi , Nakagawa Takashi , Tagami Sanae
Published: February 2005

Stress-optical coefficients in the glassy state (C
g) were measured in polycarbonates (PCs), and mechanisms of birefringence production by stress and relationships between C
gs and chemical structures were discussed.
Surface Structure of Ion-Implanted Silica Glass
Authors: Fukumi Kohei , Chayahara Akiyoshi , Satou Mamoru , Hayakawa Junji , Hangyo Masanori , Nakashima Shin-ichi
Published: February 2005

The structure of silica glass implanted with O+, B+ and Ag+ at an acceleration energy of the order of MeV has been investigated by infrared reflection and Raman scattering spectroscopies. It is found that the Si–O–Si bond angle decreases with ion implantation. Three-fold siloxane rings are formed with ion implantation. It is deduced that compaction of silica glass caused by ion implantation is attributed to the decrease in the Si–O–Si bond angle and the formation of small siloxane rings. The modification of the silica glass structure caused by ion implantation is similar to that caused by neutron irradiation.
Epitaxial Growth of Iron and Vanadium Films Vacuum-Evaporated onto a Copper Buffer Layer
Authors: Ando Yoshinori , Dingley David J.
Published: February 2005

Epitaxial growth of iron and vanadium films vacuum-evaporated onto a copper (111) buffer layer was examined by transmission electron microscopy. In order to reveal fine details of each film, an ion-milling system was effectively applied. The pseudomorphism of thin iron films evaporated onto copper was discussed according to the electron diffraction pattern and moiré fringes observed in two-layer films. The coexistence of two typical orientation relationships between bcc and fcc metal films, namely Kurdjumov-Sachs and Nishiyama-Wassermann orientations, and continuous distribution between them were confirmed by electron diffraction patterns for two-layer films, Fe/Cu and V/Cu.
Static Charge Elimination of Charged Matter Using UV Lamp
Authors: Gosho Yasushichi , Yamada Manabu , Saeki Masamori
Published: February 2005

Static charge elimination of a charged matter can be achieved using a low pressure quartz mercury lamp. Positive charge elimination is by photoelectrons emitted from the quartz surface of the lamp and negative charge elimination by photoelectrons emitted from the charged matter. This technique can be used in the case where inflammable gases are present and be used even under vacuum conditions.
Damage Caused by Stored Charge during ECR Plasma Etching
Authors: Samukawa Seiji
Published: February 2005

The influence of stored charge caused by changing the plasma parameter can be accurately shown by measuring the leakage current in CMOS-inverter integrated circuits. The leakage current increase is due to nonuniform ion current density distribution and self-bias voltage at the point of ECR plasma discharge turn-off. Positive charge ions are stored by the ion current density difference on a wafer. Moreover, a large voltage across the gate oxide is generated by the self-bias voltage at the point of ECR plasma discharge turn-off, and finally degrades the gate oxide.
Growth of Bulk CuGaS2 Single Crystals Using Solution Bridgman Method
Authors: Miyake Hideto , Sugiyama Koichi
Published: February 2005

Bulk CuGaS2 single crystals have been grown using a modified Bridgman technique from In solutions (solution Bridgman method). At temperatures below 1020°C, where a miscibility gap exists in the In solutions with a stoichiometric CuGaS2 solute, sulfur-excess In solutions are required for obtaining single crystals. The crystals are generally CuGa
x
In1-x
S2 alloys with (1-x)=0.03–0.06 due to partial occupation of Ga sites by In atoms.
Formation of Cubic Boron Nitride Films on Diamond by Plasma CVD Technique
Authors: Okamoto Masaki , Utsumi Yoshiharu , Osaka Yukio
Published: February 2005

Cubic boron nitride (c-BN) thin films could be deposited on diamond using the plasma chemical vapor deposition (CVD) technique at low pressure. The deposited films are characterized by infrared absorption spectroscopy and reflection high-energy electron diffraction (RHEED). The c-BN phase on diamond can be synthesized at the appropriate self-bias and microwave power. In contrast to the Si substrate, the peeling of the c-BN phase from the diamond substrate has not been observed for six months. The RHEED pattern of c-BN film on diamond shows that the c-BN film consists of microcrystals.
A New Droplet Breakup Model for Dimer Ion Formation from a Gallium Liquid Metal Ion Source
Authors: Hornsey Richard , Ishitani Tohru
Published: February 2005

It is demonstrated that energy distribution curves for Ga2
+ found in the literature are inconsistent with existing models of cluster ion formation in liquid metal ion sources (LMIS). A new model for the rapid breakup of metastable droplets away from the emitting area is proposed to explain gallium dimer ion formation. Simple calculations are performed to establish the feasibility of this mechanism, and the practical application of this model is discussed in detail.
RF Plasma Production at Ultralow Pressures with Surface Magnetic Confinement
Authors: Shirakawa Teruyuki , Toyoda Hirotaka , Sugai Hideo
Published: February 2005

A 13.56 MHz rf inductively coupled plasma was maintained at pressures as low as 2.7×10-3 Pa (2×10-5 Torr) with the use of multidipole magnetic confinement. When more than 90% of the inner wall area was covered with surface magnetic fields, the plasma potential drastically decreased from 80 V to 20 V. These observations were consistent with ambipolar diffusion in partially magnetized plasmas. Additional potential control by an externally biased target was possible over a wide range without changing the plasma density. This large-diameter plasma at very low neutral pressures is promising for new plasma processing techniques.
Oxide-Powder-Covered Annealing in GaAs
Authors: Yoshida Masato , Shimizu Kazushi , Ishibashi Hiroyuki , Susa Kenzo
Published: February 2005

Annealing was performed on GaAs single crystals covered with Ga2O3 powder under reduced pressure. The annealing at 820°C produced a thin film of about 2 µm on the crystal surface. The film was confirmed to be an oxide substance containing β-Ga2O3. The Hall effect measurement revealed that, with oxide powder, the surface region where the change of electrical properties can be minimized to a few microns while without oxide powder, this figure increases to over 200 µm. This is explained by the capping effect of the film to prevent a thermal decomposition of GaAs.
Photoluminescent Properties of AlAs/AlxGa1-xAs (x=0.5) Disordered Superlattices
Authors: Kasu Makoto , Yamamoto Teiji , Noda Susumu , Sasaki Akio
Published: February 2005

The AlAs/Al0.5Ga0.5As disordered superlattice is fabricated, and its photoluminescent properties are compared with those of Al0.76Ga0.24As bulk alloy and the (AlAs)2(Al0.5Ga0.5As)2 ordered superlattice. Their macroscopic AlAs compositions are almost the same, 0.75, but their microscopic structures are different. Among them, the AlAs/Al0.5Ga0.5As disordered superlattice exhibits the highest photoluminescent intensity at 4.2 K. A red shift is observed in a photoluminescent peak.
High Critical Current Density in Silver-Sheathed Bi2Sr2Ca1Cu2AgyOx Tape
Authors: Asano Toshihisa , Tanaka Yoshiaki , Fukutomi Masao , Maeda Hiroshi
Published: February 2005

Silver-sheathed Bi2Sr2Ca1Cu2Ag
y
O
x
(y=0 or 0.8) tapes were fabricated by the powder-in-tube method and a calcination procedure including a heat treatment in vacuum or in an atmosphere of reduced oxygen partial pressure. These tapes show critical current densities of 8.88×104 A/cm2 in the field of 1 T and 4.37×104 A/cm2 in the field of 12 T at 4.2 K, respectively. The addition of silver improves the critical current density. The sintering even in the atmosphere of inert gas was confirmed to also be effective for realizing high critical current density.
Temporal and Spatial Behavior of the Field-Induced Transition between Antiferroelectric and Ferroelectric Phases in Chiral Smectics
Authors: Johno Masahiro , Itoh Keizou , Lee Ji , Ouchi Yukio , Takezoe Hideo , Fukuda Atsuo , Kitazume Tomoya
Published: February 2005

Optical transmittance change and stroboscopic micrographs have been obtained in homogeneously aligned thin cells of S-MHPOBC, C8H17O–--COO–COO-*CH(CH3)C6H13, and R-TFMNPOBC, C8H17O–--COO–-COO-*CH(CF3)C8H17, by varying the initial applied DC voltage stepwise into the final one across the threshold. There exist two components, fast and slow, in the transmittance change due to the phase transition from antiferroelectric SmCA
* to ferroelectric SmC*. The fast component is due to the pretransitional effect. The movement of the domain boundaries is responsible for the slow component. In the transmittance change due to the transition from SmC* to SmCA
*, only the slow component is observed. The movement speed is mainly determined by the difference between the final and threshold voltages.
Reduction of the Surface Resistance of YBa2Cu3O7-x Pellets and Thick Films by Adding Ag
Authors: Ishii Osamu , Konaka Tsuneo , Sato Makoto , Koshimoto Yasuhiro
Published: February 2005

This letter describes the effect of Ag addition on the surface resistance of sintered YBa2Cu3O7-x
superconductors at 17 and 50 GHz. The surface resistance decreases more than 50% by adding Ag into a pellet or a thick film of YBa2Cu3O7-x
. The thick film exhibits a surface resistance of 22 mΩ at 17 GHz and at 77 K, which is almost equal to that of pure Cu. It is also revealed that the surface resistance is proportional to the square of the frequency. These phenomena are discussed in terms of the effect of Ag on the morphologies and c-axis orientation of YBa2Cu3O7-x
grains.
Direct Observation of Flux Behavior in High-Tc Oxide Superconductors Using The Faraday Effect of Iron Garnet Films
Authors: Gotoh Satoshi , Koshizuka Naoki , Yoshida Masashi , Murakami Masato , Tanaka Shoji
Published: February 2005

A new direct observation method for the dynamical magnetic flux behavior in superconductors was developed by using the Faraday effect of an iron garnet film with perpendicular magnetization and stripe domains. The domain structure observed optically in the iron garnet film in contact with an YBa2Cu3O
x
sample reveals the magnetic field distribution of the latter. It was found that the flux gradient was nonuniform due to the inhomogeneous distribution of fine Y2BaCuO5 inclusions, and the region with the largest pinning force was located in the sample used.
Preparation and Properties of Superconducting Copper Oxides (Pb, Cu)(Sr, Ba)2(Y, Ca)Cu2Oz
Authors: Ono Akira , Uchida Yoshishige , Takenouchi Satoshi
Published: February 2005

Single-phase samples of the new superconductor (Pb, Cu)(Sr, Ba)2(Y, Ca)Cu2O
z
(1212 phase) were prepared at 920°C in air, and the solubility limits of Pb, Ba and Ca in the 1212 phase were studied. For three single-phase samples and one almost-single-phase sample, the T
c's were determined by the ac susceptibility. It is found that the T
c depends on the oxygen and Ca contents of the 1212 phase.
Partial Melt Growth Process of Bi2Sr2Ca1Cu2Ox Textured Tapes on Silver
Authors: Kase Jun-ichiro , Togano Kazumasa , Kumakura Hiroaki , Dietderich Daniel R. , Irisawa Naoshi , Morimoto Takeshi , Maeda Hiroshi
Published: February 2005

Bi2Sr2Ca1Cu2O
x
textured tapes with an excellent J
c were synthesized by doctor-blade casting and a melt process. Green tape was laid on a silver foil and oxide/silver composite tape was heat treated. A highly textured microstructure was formed by slow cooling from 890°C to 870°C with the oxide in a partially melted state. The highest T
c and J
c (77 K, 0 T), 89 K and 1.3×104 A/cm2, respectively, were obtained by quenching from 870°C. However, J
c at 4.2 K was higher for the sample slowly cooled to room temperature and reached 1.4×105 A/cm2 at 25 T. These results indicate the potential for the practical application of Bi-based oxide superconductors at both 77 K and 4.2 K.
Optical Properties of Bi-Sr-Ca-Cu-O Thin Films
Authors: Hirochi Kumiko , Mizuno Koichi , Matsushima Tomoaki , Ichikawa Yo , Hayashi Shigenori , Adachi Hideaki , Setsune Kentaro , Wasa Kiyotaka
Published: February 2005

The optical reflectivity and absorption spectra for the Bi2Sr2Ca
n-1Cu
n
O
x
systems (n=1, 2 and 3) were measured at room temperature using c-axis-orientated films. In the reflectivity spectra, the increase of n enhanced a Drude-like reflection and shifted its plasma edge to the shorter-wavelength region. In the absorption spectra, a near-infrared absorption was enhanced with increasing n, contrasting with an insulating Bi2Sr2NdCu2O
x
film where an interband absorption in the visible region was dominant. These features should reflect the electronic structure which gives rise to the superconductivity.
Correspondence between Smectic Layer Switching and DC Hysteresis of Apparent Tilt Angle in an Antiferroelectric Liquid Crystal Mixture
Authors: Johno Masahiro , Ouchi Yukio , Takezoe Hideo , Fukuda Atsuo , Terashima Kanetsugu , Furukawa Kenji
Published: February 2005

We have shown that field-induced antiferro-ferroelectric phase transition is accompanied by reversible smectic layer switching. A layer structure without any electric field applications forms a chevron structure of the same kind as in ordinary SmC*. After the application of a field, the field-induced bookshelf structure relaxes to an obtuse chevron structure. The texture change with focal conics or zigzag defects is interpreted by taking account of the field dependence of the layer tilt angle of the chevron structure. The origin of the layer switching is also discussed on the basis of the texture change.
Deposition of YBa2Cu3Oy Thin Films on Metallic Substrates by Laser Ablation
Authors: Saitoh Junichi , Fukutomi Masao , Tanaka Yoshiaki , Asano Toshihisa , Maeda Hiroshi , Takahara Hidefusa
Published: February 2005

The growth of superconducting YBa2Cu3O
y
thin films on a metallic substrate has been attempted by a YAG laser ablation technique. An amorphous MgO thin film was found to be a promising buffer layer when Ni-based alloys were used as the substrate. The highest zero resistance temperature, T
c( ρ=0), was 86.0 K in its as-grown state and a transport critical current density, J
c, was 8.6×103 A/cm2 at zero field and 77.4 K. The causes of the low J
c were briefly discussed, particularly with respect to the misalignment of the crystal structure of the films.
Weak Ferromagnetic Moment and Oxygen Stoichiometry of La2NiO4
Authors: Shimokawara Yoichi , Kohn Kay
Published: February 2005

Magnetic properties of polycrystalline La2NiO4+x
were studied through the measurements of thermoremanent magnetization in samples reduced with a sealed-off tube technique. The orthorhombic distortion and magnetic properties were found to be strongly influenced by the amount of excess oxygen x. La2NiO4+x
with very small x had an ordered magnetic state specified with a small ferromagnetic moment up to relatively high temperature, while the one with more excess oxygen was also a weak ferromagnet with lower Curie temperture. The existence of two magnetically different phases was inferred from the results.
Generation of Tunable Ultraviolet/Visible Radiation by Sum-Frequency Mixing in Barium Borate
Authors: Bhar G. C. , Chatterjee U. , Das S.
Published: February 2005

A Nd:YAG laser, its harmonic and the same pumped dye laser are used for the generation of tunable ultraviolet/visible radiations in barium metaborate crystal by noncollinear sum-frequency mixing.
Fast and Efficient Photon-Gated Burning of Persistent Spectral Holes in Donor-Acceptor Electron Transfer Systems
Authors: Suzuki Hiroyuki , Shimada Toshiyuki , Nishi Toshihiro , Hiratsuka Hiroaki
Published: February 2005

Extremely fast and highly efficient burning of persistent spectral holes was observed for metal-free tetraphenylporphine with halogenated anthracene derivatives in poly(methylmethacrylate) or poly(ethylene) film. Persistent spectral holes were burnt when the system was irradiated with two 2.5 ns pulses [energy: 0.6 mJ/(cm2·pulse)], or with two 1 or10 µs pulses [energy: 60 pJ/(cm2·pulse)] at about 645 nm. The hole formation yield is independent of the time interval between frequency-selective and gating excitation up to as long as 2 min, suggesting the participation of a stable intermediate state in the reaction.
Current Imaging Tunneling Spectroscopy of Thin n-GaAs/p-GaAs Multilayer Structures in Air
Authors: Kato Takashi , Tanaka Ichiro , Sugiyama Nao-haru , Osaka Fukunobu
Published: February 2005

Cleaved n-GaAs (100 nm)/p-GaAs (100 nm) multilayer structures were investigated in air by current imaging tunneling spectroscopy (CITS). The n-GaAs and the p-GaAs layers were clearly identified in the current image. The tunneling current-voltage (I-V) spectra of the p-GaAs (n-GaAs) layers revealed band bending due to oxidation under atmospheric conditions. It was also determined that the I-V characteristics of the n-GaAs and p-GaAs layers transitively varied near the pn junctions.
In Situ RHEED Observation of CeO2 Film Growth on Si by Laser Ablation Deposition in Ultrahigh-Vacuum
Authors: Yoshimoto Mamoru , Nagata Hirotoshi , Tsukahara Tadashi , Koinuma Hideomi
Published: February 2005

In a newly developed ultrahigh-vacuum (UHV) film preparation system equipped with in situ reflection high-energy electron diffraction (RHEED) and X-ray photoelectron spectrometer (XPS) analyzer, a sintered CeO2 target was ablated by ArF excimer laser to deposit films on Si(001), (111) and (110) substrates at temperatures ranging from 600 to 700°C. Tetravalence of the Ce in the films was confirmed by XPS, indicating that stoichiometric CeO2 was formed even in the UHV (≤10-6 Torr) condition. The orientation of deposited CeO2 films was strongly dependent on the surface state of Si substrates. The results are well explained in terms of preferential arrangement of the first plane of growing CeO2 by its interaction with substrate surface.
Microchannel Spatial Light Modulator Using Liquid Crystal for Modulating Material
Authors: Mukohzaka Naohisa , Hara Tsutomu , Suzuki Yoshiji
Published: February 2005

Optical parallel processing is an attractive technique for treating today's vast quantities of information in parallel. In this field, a spatial light modulator which modulates the light in two dimensions is required. We have developed a microchannel spatial light modulator (MSLM) using LiNbO3 for a modulating material. However, it has physical limitations in readout light intensity, the spatial resolution and operating speed. In order to improve the characteristics of MSLM, liquid crystal (LC) is adopted for the modulating material. In this paper, the structure of the device and the operating principle are explained. The basic experimental results of the device are also shown.
Phase Separation and Solid Solution in Nonstoichiometric and Stoichiometric (Sr, Mg)TiO3 Ceramics
Authors: Kawada Yukihiro , Fujimoto Masayuki
Published: February 2005

Phase separation and solid solution of stoichiometric and nonstoichiometric (Sr, Mg)TiO3 ceramics were studied using HR-AEM (high-resolution analytical electron microscopy). SrTiO3 and MgTiO3 phase separation was observed in all specimens. In addition, a small amount of MgTi2O5 was detected in a B-site-excess specimen. Mg solid solution to SrTiO3 could not be detected, but Sr solid solution to MgTiO3 was detected. This arose from the different structural packing density between the SrTiO3 perovskite structure and the MgTiO3 ilmenite structure.
An Optical Pattern Classification Using Computer-Generated Holograms
Authors: Kajiki Yoshinori , Matsushita Kenji , Shimizu Eiji
Published: February 2005

We have proposed an optical pattern classification system which performs weighting and summation by the optical system using computer-generated holograms (CGHs). Our system makes it possible to simplify the structure and to improve the processing speed. We propose a trainable pattern classification system which can perform weight modification by using a CGH matrix and a dot matrix liquid crystal display (LCD) as a shutter array. We describe the trainable pattern classifier using a CGH matrix and LCD, and present the experimental results.
Multiple Imaging and Multiple Fourier Transformation Using Microlens Arrays
Authors: Hamanaka Kenjiro , Kishimoto Takashi
Published: February 2005

A new type of coherent multiple imaging system using microlens arrays has been developed. The principles, features, basic functions and possible applications are also discussed with some experimental results which are implemented by using a planar microlens array fabricated by an ion exchange technique. An experimental result of the multichannel matched filtering has also been demonstrated.
Growth Kinetics of Microscopic Silicon Rods Grown on Silicon Substrates by the Pyrolytic Laser-Induced Chemical Vapor Deposition Process
Authors: Park Se Il , Lee Sang Soo
Published: February 2005

By using a cw Ar+ ion laser beam, microscopic crystalline silicon rods ≈102 µm in diameter and ≈103 µm in height have been grown on a silicon substrate by pyrolytic dissociation of SiH4. The kinetics of lateral growth of the silicon rods is derived from the time integration of the Arrhenius equation using a reasonable assumption that the temperature on the edge of the deposit saturates inversely to the substrate temperature with illumination time. For the axial growth, excluding the initial transient growth, the same result as Bäuerle and his collaborators is derived. The influences of laser power and illumination time on the deposited diameter and height are found experimentally, and it is found that the derived theory agrees well with the experimental results.
Optical Computing and Image Processing Using Photorefractive Gallium Arsenide
Authors: Cheng Li-Jen , Liu Duncan T. H.
Published: February 2005

Photorefractive GaAs has attractive features of fast response times and operation at near infrared wavelengths. This has opened new research opportunities which can lead to valuable applications in optical computing and image processing. This paper presents recent experimental results on matrix-vector multiplication and multiple four-wave mixing using GaAs. A combination of these two configurations provides potential architectures to build optical interconnects and neural network modules.
Optical Implementation of a Neural Network Associative Memory Using Diffraction Gratings
Authors: Weible K. J. , Pedrini G. , Xue W. , Thalmann R.
Published: February 2005

A neural network associative memory based on diffraction gratings is presented. The theoretical computational capability of the system is discussed and experimental results are presented.
An Optoelectronic Synaptic Connection Circuit with Variable Analog and Nonvolatile Weights
Authors: Yonezu Hiroo , Himeno Toshihiko , Kanamori Kohji , Pak Kangsa , Takano Yasushi
Published: February 2005

An artificial synaptic connection circuit was constructed using an optical interconnection and a nonvolatile memory device. Nonvolatile analog synaptic weights were realized, which were varied electrically and operated at a low current level. The possibility of a remarkable reduction of the number of electric wires was verified, which could lead to a realization of a large scale one-chip OEIC using a conventional wiring technique in Si LSIs.
Preparation of Pb(Zn0.52Ti0.48)O3 Films by Laser Ablation
Authors: Otsubo Shigeru , Maeda Toshihiro , Minamikawa Toshiharu , Yonezawa Yasuto , Morimoto Akiharu , Shimizu Tatsuo
Published: February 2005

Pb(Zr0.52Ti0.48)O3 films were prepared on an r-plane sapphire substrate by laser ablation using the ArF excimer laser. This is the first report on the preparation of Pb(Zr0.52Ti0.48)O3 films by laser ablation. The composition of the deposited films was found to be fairly close to the composition of the target material for a wide range of the substrate temperature, 400–750°C. The substrate temperature greatly influences the crystal structure; a low substrate temperature produces a pyrochlore phase and a high substrate temperature (750°C) a perovskite phase.
Effect of AlAs Buffer Layers on Epitaxial Growth of GaAs on Si (100)
Authors: Kobayashi Hidetoshi , Kawabe Mitsuo
Published: February 2005

Dislocation density and full width at half maximum (FWHM) of X-ray diffraction of GaAs grown on Si substrates are reduced with thin AlAs buffer layers grown by migration-enhanced epitaxy. Reflection high-energy electron diffraction (RHEED) and Auger measurements indicate that this is attributable to the layerlike growth of AlAs. There is an optimum AlAs buffer layer thickness. The minimum etch pit density and the minimum FWHM of X-ray diffraction are obtained at the thickness of 35 monolayers of AlAs. They are 6×106 cm-2 and 183 arcsec, respectively.
Decomposition of Arsine and Trimethylarsenic on GaAs Investigated by Surface Photo-Absorption
Authors: Yamauchi Yoshiharu , Makimoto Toshiki , Kobayashi Naoki , Horikoshi Yoshiji
Published: February 2005

The decomposition processes of arsine (AsH3) and trimethylarsenic (TMAs) on a GaAs surface are investigated in situ in an MOCVD reactor by the surface photo-absorption (SPA) method. This method is based on measuring the reflectivity of p-polarized light incidence at the Brewster angle. Small changes in reflectivity at the surface can be detected with a high signal-to-noise ratio. When 325-nm He-Cd laser light is used during Ga deposition on an As surface, the reflectivity increases in proportion to the Ga coverage and saturates after the complete growth of one Ga atomic layer. When the AsH3 supply in resumed, the reflectivity drops and approaches the initial value of the As surface as As coverage increases. Therefore, the decomposition of As precursors on a GaAs substrate surface can be studied by observing the decay in reflection intensity. From the substrate temperature dependence of decay lifetime, activation energies were calculated to be 17 kcal/mol and 65 kcal/mol for AsH3 and TMAs, respectively. These results suggest that the catalytic effect of the GaAs surface reduces the decomposition energy in AsH3, much more than in TMAs.
Incorporation Behavior of Si Atoms in the Molecular Beam Epitaxial Growth of GaAs on Misoriented (111)A Substrates
Authors: Okano Yoshimichi , Shigeta Mitsuhiro , Seto Hiroyuki , Katahama Hisashi , Nishine Shiro , Fujimoto Isao
Published: February 2005

The molecular beam epitaxial growth of Si-doped GaAs on slightly (1–5°) misoriented (111)A substrates was examined. Occupation sites of Si were greatly affected by the tilted angle, the flux ratio and the substrate temperature. In the growth on an exactly (111)A-oriented substrate at low flux ratio, substantially all Si atoms acted as acceptors. With increase of the tilted angle and/or the flux ratio and with decrease of the substrate temperature, the number of donor site Si atoms increased. A doping mechanism including preferential decomposition of As4 molecules at the steps was proposed.
The Frozen-in Defects and Origin of Magnetic Centres in Phosphorus-Doped a-Si:H
Authors: Morigaki Kazuo
Published: February 2005

A model for the frozen-in defects responsible for the thermal equilibrium phenomenon in phosphorus-doped a-Si:H is presented. The origin of an ESR line of g=2.004 and hyperfine lines is also discussed in relation to this phenomenon.
S-Shaped Negative Differential Resistance in a Single GaAs Quantum-Well Switching Device
Authors: Liu Wen-Chau , Lin Ching-Hsi , Sun Chung-Yih , Lour Wen-Shiung
Published: February 2005

A new GaAs-AlGaAs switching device with planar-doped barriers and a GaAs quantum well grown by molecular beam epitaxy and exhibiting S-shaped negative differential resistance (NDR) has been fabricated. The NDR phenomenon is attributed mainly to impact ionization within the undoped collector region. Furthermore, the studied NDR properties are very sensitive to the environmental temperature.
Magnetic Properties and Superconductivity of YBa2(Cu1-xFex)3Oy
Authors: Furubayashi Takao , Matsumoto Takehiko
Published: February 2005

Magnetic properties of YBa2(Cu1-x
Fe
x
)3O
y
(x=0.05∼0.15, y≃7) were investigated by magnetometry and Mössbauer spectroscopy. The temperature dependence of the susceptibility of the sample with x=0.15 (not superconducting) exhibited a cusp which is explained as the evidence of spin glass transition. Mössbauer spectra at low temperatures exhibited hyperfine splitting, whether the sample was superconducting or not. We suggest that the magnetic splittings come from spin glass, not from paramagnetic slow relaxation phenomena.
Investigation of the Si Oxidation Process by XANES Spectroscopy Using Synchrotron Radiation
Authors: Sekiyama Hideo , Nakazawa Masatoshi , Kawase Susumu
Published: February 2005

Initial oxidation of Si(100) and Si(111) surfaces has been investigated by XANES (X-ray absorption near-edge structure) spectroscopy using synchrotron radiation. At room temperature, oxidation of Si(111) surfaces proceeds much faster than that for Si(100) surfaces. The XANES spectra indicate that oxygen is atomically adsorbed onto the Si surfaces in initial stages of oxidation at room temperature. As oxidation on the surface proceeds, the XANES spectra exhibit the formation of a continuum shape resonance. The local electronic states and the local site structure for the progressive oxidation process are discussed.
Synthesis of Superconducting 2223 Compound in the Lead-Added Bi-Sr-Ca-Cu-O System
Authors: Liang Ruixing , Ishii Hisashi , Kawaji Hitoshi , Itoh Mitsuru , Nakamura Tetsurō
Published: February 2005

We report the synthesis of 2223 compound in the lead-added Bi-Sr-Ca-Cu-O system by reacting (Sr, Ca)CuO2 and (Bi, Pb, Ca)2O3-z
. Samples of nearly single 2223 phase with T
c(zero resistivity)>100 K were obtained after calcination for 36 h using this method, as compared to ≈50% 2223 phase for batches of mixed oxides and carbonates obtained by a similar calcination schedule.
Degradation of High-Temperature Superconductor YBa2Cu3O7-x in Water
Authors: Yokota Katsuhiro , Kura Takeshi , Ochi Mitsukazu , Katayama Saichi
Published: February 2005

The degradation of YBa1Cu3O7-x
(YBCO) sintered disks was examined by soaking the disks in water at 25°C. By magnetic susceptibility measurements, the degree of the degradation was found to depend on the pressure aplied when forming the disk from YBCO powders. From the analysis of our results, we derived an optimum pressure of 16.5 kbar to minimize degradation.
Preparation of Ca-Doped YBaCuO Thin Films Containing 248 Phase by RF Magnetron Sputtering
Authors: Kuroda Ken'ichi , Kojima Kazuyoshi , Tanioku Masami , Yokoyama Kazuo , Hamanaka Koichi
Published: February 2005

Ca-doped YBaCuO thin films containing predominantly a 248 phase were prepared on SrTiO3(100) substrates by sputtering three Ca-doped targets at 500°C and annealing at 750°C. The as-deposited films formed at above 500°C predominantly had a 123 phase, and those at 300°C were amorphous. On the other hand, the as-deposited films obtained at 400–500°C had an unidentified major phase with a lattice spacing of 7 Å, which changed into a 248 phase by annealing, whereas the phase of amorphous films and the 123 phase did not.
Temperature-Dependent Br K-Edge EXAFS Study on AgBrxCl1-x Solid Solutions
Authors: Yokoyama Toshihiko , Takamatsu Fumiko , Seki Kazuhiko , Miyake Kiyoteru , Tani Tadaaki , Ohta Toshiaki
Published: February 2005

Local structures of AgBr
x
Cl1-x
solid solutions were investigated by means of Br K-edge EXAFS spectroscopy with the Br composition x varying from 0.05 to 1. The virtual crystal approximation did not hold as in other solid solutions investigated previously, although the Br-Ag bond distance noticeably varies with x. It was found for the first time that the x dependence of the Br-Ag distance is more significant at lower temperature than at room temperature. Such a new finding can be explained by the suppression of the long-range force with increasing temperature, compared with the short-range force.
Optical Recording Utilizing Conducting Polymers, Poly(p-phenylene vinylene) and Its Derivatives
Authors: Yoshino Katsumi , Kuwabara Takao , Iwasa Toshinori , Kawai Tsuyoshi , Onoda Mitsuyoshi
Published: February 2005

Optical recording has been performed successfully by the preirradiation of light upon the precursor of a conducting polymer such as poly(p-phenylene vinylene) and its derivatives and subsequent thermal treatment and washing with water. The effect has been tentatively interpreted in terms of the deterioration of the irradiated area of the precursor film in which polymerization is suppressed. The application of this phenomenon for lithography has been also proposed.
Dissolution of Hydroxyapatite-Glass-Titanium Composite and HAP-Precipitation on Surface in vitro
Authors: Ban Seiji , Maruno Shigeo , Hasegawa Jiro
Published: February 2005

Hydroxyapatite (HAP)-glass-titanium composites were soaked for 60 days in 0.001 N HCl solution (pH=2.8), distilled water (pH=5.8), 0.01% ammonia solution (pH=10.6), and simulated body fluid (SBF; pH=7.1). The composites demonstrated a large weight loss and a large Ca dissolution in HCl solution, whereas Na and K dissolution was negligible. After soaking in the SBF, the weight loss from the HAP-glass-composite and the glass specimens was small, and then the surface of each composite after immersion was covered by a precipitate of HAP from the SBF.
Variable Nonlinear Transfer Characteristics of MSLM
Authors: Kobayashi Yuji , Hara Tsutomu , Suzuki Yoshiji
Published: February 2005

The thresholding nonlinearities of MSLM can be accomplished either by mesh voltage change or by writing time change. Variable nonlinear transfer characteristics of MSLM are discussed.
Computer-Generated Hologram Using TFT Active Matrix Liquid Crystal Spatial Light Modulator (TFT-LCSLM)
Authors: Amako Jun , Sonehara Tomio
Published: February 2005

A real-time Lee-type computer-generated hologram (CGH) using a TFT-LCSLM is presented. The LCSLM is very well suited for recording a CGH because of its high resolution, low cross talk and high contrast ratio. We examine both amplitude and phase characteristics of the LCSLM. We consider the effects of contrast ratio and phase shift in twisted nematic (TN) mode operation, and clarify the optimum configuration between the LCSLM and two polarizers to obtain a high-quality image.
Application of Laser Fluorescence Spectroscopy by Two-Photon Excitation into Atomic Hydrogen Density Measurement in Reactive Plasmas
Authors: Kajiwara Toshinori , Takeda Kazuyuki , Kim Hee Je , Park Won Zoo , Okada Tatsuo , Maeda Mitsuo , Muraoka Katsunori , Akazaki Masanori
Published: February 2005

Density profiles of hydrogen atoms in reactive plasmas of hydrogen and methane gases were measured, for the first time, using the laser fluorescence spectroscopy by two-photon excitation of Lyman beta transition and observation at the Balmer alpha radiation. Absolute density determinations showed atomic densities of around 3×1017 m-3, or the degree of dissociation to be 10-4. Densities along the axis perpendicular to the RF electrode showed peaked profiles, which were due to the balance of atomic hydrogen production by electron impact on molecules against diffusion loss to the walls.
2-D Array of Optoelectronic Logic XNOR Gates for Bipolar Binary Optical Processing
Authors: Zhai Hongchen , Jaspert R. , Schlier S. , Jäger D.
Published: February 2005

A new method is introduced, where bipolar binary values are directly expressed by the two levels of light intensity. An array of optoelectronic logic XNOR gates is used to execute the processing of vector-matrix products or inner-product correlation. Optical implementation of neural networks based on the Hopfield model is described as an example to show one of the possible applications of this novel method.
Interferometric Spectral Imaging and Optical Three-Dimensional Fourier Transformation
Authors: Itoh Kazuyoshi , Inoue Takashi , Ichioka Yoshiki
Published: February 2005

A three-dimensional (3-D) Fourier transform relationship associated with the 3-D spatial coherence of an optical wave field generated by a polychromatic incoherent light source is addressed. Applications to optical 3-D Fourier transformation is discussed and an experimental demonstration is presented.
Low-Temperature Static Magnetic Susceptibility of Al0.3Ga0.7As with DX Centers
Authors: Katsumoto Shingo , Matsunaga Noriaki , Yoshida Yasuhiro , Sugiyama Katsuyuki , Kobayashi Shun-ichi
Published: February 2005

We have measured the static magnetic susceptibility of Al0.3Ga0.7As doped with 1×1018 cm-3 Te from 20 mK to 1 K in order to study the electron ground state of the DX center. We observed Curie-law temperature dependence of the susceptibility which should come from some paramagnetic centers. The concentration of the paramagnetic center assuming g=2 and spin 1/2 is much lower than that of the DX center. The result indicates that the ground state of the DX center has no spin, thus supporting the negative–U picture of the ground state of the DX center.