bluuebunny/crossref_metadata_2025 huggingface dataset:
Weak Flax-Pinning Effect between 230 K and 40 K in La1.8Sr0.2CuO4
Authors: Iwazumi Toshiaki , Yoshizaki Ryozo , Sawada Hideaki , Hayashi Hiroaki , Ikeda Hiroshi , Matsuura Etsuyuki
Published: November 2005

Thermal hysteresis measurement of the magnetization of La1.8Sr0.2CuO4 revealed weak flux-pinning effect below 230 K. The hysteresis was observed in weak magnetic field and disappeared above 0.3 T. The result was similar to the flux pinning in type-II superconductors.
Preparation of (La1-xSrx)2CuO4-δ Superconducting Films by Screen Printing Method
Authors: Koinuma Hideomi , Hashimoto Takuya , Kawasaki Masashi , Fueki Kazuo
Published: November 2005

(La1-x
Sr
x
)2CuO4-δ(LSCO) films were prepared by a screen printing method. Electrical properties of the films were strongly dependent on sintering time and especially on substrate material. Quartz and corning #7059 substrates are found to react with LSCO under high-temperature sintering conditions. Crack formation was observed in the films printed on alumina substrates and sintered at 1000°C. Superconducting films could be obtained by using yttrium stabilized zirconia (YSZ) and La2CuO4 as substrates; T
c onset of 42 K and the temperature of zero resistivity as high as 25 K were achieved.
Transport Properties and Specific Heat of (La1-xBax)2CuO4-y
Authors: Maeno Yoshiteru , Aoki Yuji , Kamimura Hirohiko , Sakurai Junji , Fujita Toshizo
Published: November 2005

X-ray analysis, covering a wide temperature range between 10 and 300 K, and the measurements of the thermoelectric power and specific heat are performed on a recently discovered high-T
c superconductor, (La1-x
Ba
x
)2CuO4-y
with x=0.075. A large positive thermoelectric power is observed above T
c. The Debye temperature is 385 K and no specificheat jump is detected across T
c.
High Tc Thin Films of (La1-xMx)yCuO4-δ (M=Sr, Ba, Ca) Prepared by Sputtering
Authors: Nagata Shunroh , Kawasaki Masashi , Funabashi Makoto , Fueki Kazuo , Koinuma Hideomi
Published: November 2005

Sputtering of (La1-x
Sr
x
)
y
CuO4-δ has produced superconducting oxide films which have higher T
c values than any other oxide superconducting films so far prepared : T
c onset at 36 K and the temperature of zero resistivity at 17 K have been achieved. Superconduction was also observed in the films with partial substitution of Sr in (La1-x
Sr
x
)
y
CuO4-δ by Ba or Ca. The Meissner effect was confirmed by the measurement of dc magnetic susceptibility on the film specimen having the zero resistivity temperature of 17 K.
Infrared Spectroscopy of (La1-xMx)2CuO4-y; M=Sr, Ba, K and Ce
Authors: Ogita Norio , Ohbayashi Kohji , Udagawa Masayuki , Aoki Yuji , Maeno Yoshiteru , Fujita Toshizo
Published: November 2005

Infrared absorption spectra have been measured at room temperature for samples (La0.9Sr0.1)2CuO4-y
, (La0.925Ba0.075)2CuO4-y
, (La0.95K0.05)2CuO4-y
and (La0.9Ce0.1)2CuO4+y
. Good correspondence between the superconductivity and the infrared spectrum has been observed.
Infrared and Raman Spectroscopy of High Tc Superconducting System (La1-xBax)2CuO4
Authors: Ohbayashi Kohji , Ogita Norio , Udagawa Masayuki , Aoki Yuji , Maeno Yoshiteru , Fujita Toshizo
Published: November 2005

Infrared absorption spectra of (La1-x
Ba
x
)2CuO4-y
; (x=0, 0.02, 0.03, 0.04, 0.06, 0.075, 0.10, 0.15 and 0.20) have been measured at room temperature between the energy region from 400 to 4000 cm-1. The phonon spectra have been found to change sensitively with the change in concentration. The spectral shape has been found to show good correspondence to the crystal structure. The absorption edge of some electrical transition has been clearly observed at all compositions. The energy gap corresponding to this absorption edge has been found to be almost independent of the concentration.
Study of the Infrared Properties of (La1-xSrx)2CuO4
Authors: Sawada Hideaki , Saito Yosuke , Iwazumi Toshiaki , Yoshizaki Ryozo , Abe Yoshihito , Matsuura Etsuyuki
Published: November 2005

Reflectivity and transmission spectra of (La1-x
Sr
x
)2CuO4 were measured in the spectral range of 20-4800 cm-1. The intensity of the absorption peak around 255 cm-1 became twice with lowering temperature from 298 to 19 K accompanying weak softening, while the Cu-O asymmetric stretching mode at 510 cm-1 was almost unchanged both in its energy and intensity. The origin of the soft-phonon mode is discussed.
Electronic Structure of Perovskite LaCuO3
Authors: Takegahara Katsuhiko
Published: November 2005

The self-consistent APW band calculation for the ideal perovskite structure LaCuO3, which is a basic reference material to study the electronic structure of perovskite-related M-Cu-O compounds with M=La, Y and Sc, has been done using the local density approximation. Calculated electronic band structure is compared with that of La2CuO4 and BaPb1-x
Bi
x
O3.
A New Blanking Method for Electron Beam Lithography Using SEM
Authors: Park Sun-Woo , Shono Katsufusa
Published: November 2005

A new blanking method for electron beam (EB) lithography employing a conventional scanning electron microscope was proposed. The EB blanking for a non-exposure state was done by supplying an excess current to the condenser lens coil. Successive exposure of a square unit cell corresponding with a unit cell of our bit-map CAD gave an IC pattern on a positive or negative type EB resist. 6.0±0.2 µm minimum line width and spacing was determined at 5000 times magnification.
Electric and Magnetic Properties of La2CuO4
Authors: Uchida Shin-ichi , Takagi Hidenori , Yanagisawa Hironori , Kishio Kohji , Kitazawa Koichi , Fueki Kazuo , Tanaka Shoji
Published: November 2005

Electric and magnetic properties are investigated for La2CuO4. The properties of this material are quite sensitive to the stoichiometry of the compounds, such as oxygen deficiency. The most stoichiometric sample is semiconducting at low temperatures, exhibiting a marked increase in resistivity with ρ(10 K)/ρ(100 K)≃104. The magnetic susceptibility is weakly paramagnetic (∼10-7 emu/g) over a wide temperature range and shows a cusp at 250 K. The cusp indicates an electronic instability, most probably the formation of a spin-density-wave, taking place in this material.
Observation of the Antiferromagnetic Ordering in La2CuO4
Authors: Yamaguchi Yasuo , Yamauchi Hiroshi , Ohashi Masayoshi , Yamamoto Hisao , Shimoda Nobuyuki , Kikuchi Masae , Syono Yasuhiko
Published: November 2005

Neutron diffraction study on La2CuO4, which is the basic material of high-T
c oxide superconductors, revealed the antiferromagnetic ordering in this compound. The value of the magnetic moment is 1.1±0.3 µB per copper atom, and the Néel temperature was found to be 240±10 K from temperature dependence of the intensity of the magnetic reflection.
Effect of Residual Water on Superconductivity in (La1-xSrx)2CuO4-δ
Authors: Kishio Kohji , Sugii Nobuyuki , Kitazawa Koichi , Fueki Kazuo
Published: November 2005

Samples of (La1-x
Sr
x
)2CuO4-δ were prepared by the ceramic method under various conditions, paying particular attention on the possible effect of residual water on superconductivity. It was shown that either crystal water or absorbed water originally contained in the starting materials and/or absorbed during the preparation process, appreciably depressed the volume fraction of the superconductive region of the final product even after the prolonged heat treatment at 1100°C.
Identification of the High Tc Superconductor in the System Y-Ba-Cu-O
Authors: Takayama-Muromachi Eiji , Uchida Yoshishige , Matsui Yoshio , Kato Katsuo
Published: November 2005

In order to identify the superconducting phase in the Y-Ba-Cu-O system, phase search and electron microscopic study were performed. At least three unknown phases were found in a part of the system. Among these phases, perovskite-related compound (orthorhombic a=3.89, b=3.82, c=11.7 Å or possibly tetragonal a=3.83, c=11.7 Å) is the possible compound responsible for the superconductivity.
Far Infrared Measurements in High-Tc Superconductor SrxLa2-xCuO4-y
Authors: Nagasaka Keigo , Sato Masayuki , Ihara Hideo , Tokumoto Madoka , Hirabayashi Masayuki , Terada Norio , Senzaki Kiyoshi , Kimura Yoichi
Published: November 2005

Far infrared trasmission spectra of powdered Sr
x
La2-x
CuO4-y
at temperatures above and below T
c=37 K were measured in the range 20 to 500 cm-1. We found the absorption edge around 180 cm-1 corresponding to the energy gap E
g(0)=5 kT
c.
X-Ray Absorption Spectra of High Tc Superconducting SrxLa2-xCuO4-y
Authors: Oyanagi Hiroyuki , Ihara Hideo , Matsushita Tadashi , Tokumoto Madoka , Hirabayashi Masayuki , Terada Norio , Senzaki Kiyoshi , Kimura Yoichi , Yao Takafumi
Published: November 2005

Cu K-edge extended X-ray absorption fine structure (EXAFS) and near-edge structure have been measured in high T
c superconducting Sr
x
La2-x
CuO4-y
. The Fourir transform analysis shows the axial elongation of CuO6 octahedron along the c-axis with four short (1.89 Å) and two long (2.41 Å) Cu-O bonds, which are slightly shorter than those in CuO and La2CuO4 indicating the presence of enhanced Cu(3d)-O(2p) interaction. The near-edge spectrum of Sr
x
La2-x
CuO4-y
is similar to that of Cu2O rather than CuO, which is interpreted as an evidence for the monovalent character of Cu ions.
Superconducting Properties in Sr-La-Co-O System
Authors: Saito Yoshitami , Noji Takashi , Endo Akihiko , Matsuzaki Nozomu , Katsumata Masao , Higuchi Naoaki
Published: November 2005

The dependence of T
c of the superconducting ceramics Sr
x
La2-x
CuO4 was measured on the sintering conditions, temperature and time, on the cooling rate after annealing and on the depth from the initial surface of the sample. The sintering temperature 1050°C was better than 1000°C and the sintering for five hours was the best one. There was no difference between the superconductivity of the initial surface and of the inside of the sample.
X-Ray and Electron Microscopic Study of a High Temperature Superconductor Y0.4Ba0.6CuO2.22
Authors: Syono Yasuhiko , Kikuchi Masae , Oh-ishi Katsuyoshi , Hiraga Kenji , Arai Hide , Matsui Yoshito , Kobayashi Norio , Sasaoka Takaaki , Muto Yoshio
Published: November 2005

A superconducting oxide Y0.4Ba0.6CuO2.22 with T
c higher than 88 K was synthesized. The crystal structure was found to be a derivative of the perovskite structure with orthorhombic unit cell dimensions of a=3.818 (1) Å, b=3.888 (1) Å, c=11.667 (4) Å, and V=173.19 (8) Å3. Basic unit cell of the cubic perovskite structure was tripled along the c axis, probably due to the ordering of Y3+ and Ba2+ ions and/or of oxygen vacancy. Apparent short bond length for Cu-O may partly be explained by oxygen vacancy amounting to a quarter, but the observed high T
c suggests actual contraction of Cu-O bonds.
Lattice Parameter and Its Pressure Dependence of High Tc SrxLa2-xCuO4-y (x∼0.6) Prepared under Reducing Condition
Authors: Terada Norio , Ihara Hideo , Hirabayashi Masayuki , Senzaki Kiyoshi , Kimura Youichi , Murata Keizo , Tokumoto Madoka , Shimomura Osamu , Kikegawa Takumi
Published: November 2005

Lattice parameters of superconducting Sr
x
La2-x
CuO4-y
(x∼0.6) with T
c onset above 50 K prepared under a reducing condition and pressure dependence of the parameters have been studied. By reducing treatment, the lattice parameter c
0 at ambient pressure was shortened from 13.25 to 13.20 Å and T
c onset was increased from below 10 K to above 50 K. For the high T

c
specimen, compressibility along c-axis was larger than that along a-axis. These results suggest that the high T
c specimen with Sr content x of about 0.6 has a large amount of oxygen vacancies which are likely to be created in vertical sites of CuO6 clusters in K2NiF4 structure.
Hall Coefficient of La-Sr-Cu Oxide Superconducting Compound
Authors: Tonouchi Masayoshi , Fujiwara Yasufumi , Kita Sadamu , Kobayashi Takeshi , Takata Masasuke , Yamashita Tsutomu
Published: November 2005

Hall Coefficient of a porous La-Sr-Cu oxide superconductor (T
c.zero=32 K) have been measured. The average concentratin n
300 and mobility µ300 of electrons, the dominant carrier, are found to be 1.5×1021 cm-3 and 4.17 cm2/Vs, respectively, at room temperature. The observed n
300 decreases with increasing temperature due probably to significant capture of thermally excited electrons at dense traps existing in the grain boundary surrounding the conductive channels.
Hall Effect in Superconducting (La1-xSrx)2CuO4 Single Crystal Thin Films
Authors: Suzuki Minoru , Murakami Toshiaki
Published: November 2005

Resistivity and Hall coefficient have been measured over the temperature range below 300 K for superconducting (La1-x
Sr
x
)2CuO4 single crystal thin films epitaxially grown on SrTiO3 (100) by magnetron sputtering. It is found that the carrier density at 300 K is 6.8×1021 cm-3 and that it decreases notably with falling temperature. Carrier localization due to oxygen vacancies is briefly discussed.
Role of Ions and Radical Species in Silicon Nitride Deposition by ECR Plasma CVD Method
Authors: Hirao Takashi , Setsune Kentaro , Kitagawa Masatoshi , Manabe Yoshio , Wasa Kiyotaka , Kohiki Shigemi
Published: November 2005

The growth kinetics of silicon nitride (SiN) films prepared by the electron cyclotron resonance (ECR) CVD method have been investigated. Studying both the compositional properties of films deposited by a shielding mask to a plasma stream just above the silicon wafer and optical emission spectrometry resulting from the discharge of SiH4/N2 mixture gas and N2 gas, it is deduced that N2 ions can directly contribute to the formation of SiN films. Although N2 radicals also can play a role in SiN formation, ion- assisted effects seem to be necessary for dense SiN formation.
Effect of Oxygen Content on Defect Formation in Pure-Silica Core Fibers
Authors: Nagasawa Kaya , Hoshi Yutaka , Ohki Yoshimichi
Published: November 2005

There is slight lack of stoichiometry in pure silica glass, which varies according to the synthesis process. The lack of stoichiometry leads to defect formations: the 245 nm absorption band and drawing-induced E' centers are formed in oxygen-deficient silica, but peroxy radicals and drawing-induced 2 eV band are formed in oxygen-rich silica. The 245 nm band seems to be caused by the Si-Si bonding.
Selective Area Laser CVD of Silicon Nitride and Oxide and its Application to Microlenses
Authors: Sugimura Atsuhiko , Hanabusa Mitsugu
Published: November 2005

Selective area deposition of silicon oxide and nitride films was achieved by laser CVD based on pyrolysis. The dielectric films prepared on quartz substrates from SiH4/NH3 and SiH4/N2O mixtures using a CO2 laser were smaller in size than the beam, and their thickness profile could be reproduced from a predicted surface temperature distribution and observed temperature dependence of deposition rates. Thickness profile of oxide films was quite different when a SiH4/O2 mixture was used. Microlenses with focal lengths as short as 0.6 mm were fabricated by the present technique.
On the Reaction Mechanism of the Pyrolyses of TMG and TEG in MOCVD Growth Reactors
Authors: Tsuda Minoru , Oikawa Setsuko , Morishita Mutsuo , Mashita Masao
Published: November 2005

The differentiation of the plausible mechanism for the thermal decompositions of TMG and TEG taking place in MOCVD growth reactors was carried out by means of the quantum theoretical method using ab initio molecular orbital calculations. It was found that the combination of the radical mechanism for TMG, Ga(CH3)3–Δ·Ga(CH3)2+·CH3, and the molecular mechanism for TEG, Ga(C2H5)3–ΔGaH(C2H5)2+C2H4, explains qualitatively the experiment on the pyrolysis temperatures of TMG and TEG in the MOCVD growth reactor.
Fiber-Optic Sensor for Measuring External Forces Distributed along a Fiber
Authors: Tsubokawa Makoto , Higashi Tsunehito , Seikai Shigeyuki
Published: November 2005

A fiber-optic sensor for measuring distributed external forces applied along an optical fiber is presented. This method is based on two-beam interferometry which permits evaluation of positions and magnitudes of local mode-conversion caused by external forces. In this experiment the resolvable length was within 0.5 m for a 100 m fiber. A mode power coupling coefficient of up to 4×10-6 m-1 was also observed. This method offers many advantages for a multiplexing fiber-optic sensor.
Extremely High 2DEG Concentration in Selectively Doped In0.53Ga0.47As/N-In0.52Al0.48As Heterostructures Grown by MBE
Authors: Nakata Yoshiaki , Sasa Shigehiko , Sugiyama Yoshihiro , Fujii Toshio , Hiyamizu Satoshi
Published: November 2005

Electron mobility and 2DEG concentration in MBE-grown, selectively doped In0.53Ga0.47As/N-In0.52Al0.48As heterostructures, lattice-matched to InP, were studied as a function of Si-doping concentration in N-In0.52Al0.48As. A 2DEG concentration of as high as 3.7×1012 cm-2 (µ=22,000cm2/Vs at 77 K) was achieved with a Si-doping concentration of 5×1018 cm-3 in N-In0.52Al0.48As. This N
s value is the highest 2DEG concentration ever reported for selectively doped single-interface heterostructures, and is almost four times higher than that of conventional GaAs/N-AlGaAs heterostructures.
Identification of a Structure with Two Superconducting Phases in L-Ba-Cu-O System (L=La or Y)
Authors: Iwazumi Toshiaki , Yoshizaki Ryozo , Inoue Masahiro , Sawada Hideaki , Hayashi Hiroaki , Ikeda Hiroshi , Matsuura Etsuyuki
Published: November 2005

The superconducting transition temperature has been investigated for almost single phase (L1-x
Ba
x
)
a
Cu
b
O
c-y
compound samples where L stands for La or Y and (a,b,c) values of (6,6,14) respectively and y the oxygen deficiency has not been evaluated. The structures have tetragonal symmetry and the superconducting transition temperatures of 50 K and 54 K have been determined for the L=La and L=Y samples respectively.
Anisotropie Cooper Pairs in High-Tc Superconductors
Authors: Ohkawa Fusayoshi J.
Published: November 2005

Anisotropic Cooper pairs in high-T
c superconductors are theoretically examined by assuming two types of attractive interactions such as a superexchange interaction working between the nearest neighbor unit cells, and breathing modes of oxygen octahedrons working as attractive interactions between the second and third neighbors. Cooper pairs with d-symmetry are most probable because of strong on-site repulsive interactions. If the super exchange is the most effective, especially, the shape of Fermi surface, which is characteristic of the van Hove singularity, definitely favors Cooper pairs with dγ-symmetry (k

x

2-k

y

2).
Is Spin Density Wave Always Harmful to Superconductivity? –Tc Enhancement Due to Density Wave Instabilities–
Authors: Machida Kazushige , Kato Masaru
Published: November 2005

It is shown theoretically that the superconducting transition temperature (T
c) can be enhanced by the presence of the spin density wave (SDW). By using a two dimensional imperfect neasting model we demonstrate that the SDW can raise T
c of anisotropic pairing states by an order of magnitude higher than that (T
c0) in the absence of the SDW, but it suppresses the isotropic singlet pairing state. Its implication is discussed in light of recent high T
c oxide superconductors.
Superconducting Upper Critical Field Hc2 of High-Tc Y-Ba-Cu-O Compound System
Authors: Takita Kôki , Ippōshi Takashi , Masuda Kohzoh
Published: November 2005

Superconducting transition in the magnetic field up to 9 T and upper critical field H
c2 near T
c were investigated for several samples which have the nominal composition Y1-y
Ba
y
CuO
x
with (a) y=0.60 or (b) y=0.65 and x undetermined. (a)- and (b)-samples show zero-resistance around 88 K and multi-phase and almost-single-phase behaviors, respectively, in the magnetic field, being consistent with a recently proposed model of YBa2Cu3O
x
for a 90 K-range phase. In a (b)-sample, a very large value of (-dH
c2/dT) of 3.0∼3.5 T/K or 4.0∼4.5 T/K was observed, depending on if H
c2 was taken at the 50% of the normal state resistance R
n or the 90%. Based on a theory assuming no paramagnetic limiting, this means H
c2(0) of 200 or 250 T, the highest one among the reported values.
High Tc Superconductivity Based on the Square Planar [CuO4]∞-Bonding System K2NiF4-Type (A, A*)2CuO4 and Oxygen-Deficient Perovskite (Ba2A)Cu3O7
Authors: Nakamura Tetsurō , Liang Ruixing
Published: November 2005

Based upon the experimental evidences and inferences, the almost filled σ-electron band embedded in the extended two-dimensional or one-dimensional square planar [CuO4]∞-bonding system is identified to be the unique high T
c superconductivity possible band, because it is a pseudo-inner orbital, muffled and isolated from the outer phonon systems by the other filled, localized orbitals. A high Debye temperature θD=770-800K is evaluated for the [CuO4]∞-bonding system. An ideal structural model for (Ba2Y)Cu3O7, which explains the orthorhombic constants and the high pressure behavors of T
c of this material is proposed.
Electron Diffraction and Microscopy of the Structures of La-Ba(Sr)-Cu Oxides at Liquid Helium Temperature
Authors: Hirotsu Yoshihiko , Nagakura Sigemaro , Murata Yuzo , Nishihara Takaharu , Takata Masasuke , Yamashita Tsutomu , Iwatsuki Masashi , Harada Yoshiyasu
Published: November 2005

Structural observation of the oxides, La1.9Ba0.1CuO4 (orthorhombic, T
c<4.2 K) and La1.8Sr0.2CuO4 (tetragonal, T
c=30 K: zero resistance), was made at liquid helium temperature by means of electron diffraction and microscopy, and the results were compared with those at room temperature. For the both oxides, no differences have been found in the crystal structure and morphology between 4.2 K and room temperature, although the lattice parameters changed as a result of thermal contraction.
Effect of Annealing in High-Tc Superconducting Y-Ba-Cu Oxide
Authors: Ito Yukio , Hasegawa Haruhiro , Takagi Kazumasa , Miyauchi Katsuki
Published: November 2005

Effect of annealing under various gas flow atmosphere on the crystal structure and electrical resistivity for the high-T
c superconducting single phase in Y-Ba-Cu oxide system is investigated. When a specimen is annealed under a nitrogen or argon atmosphere, the unit cell dimensions in an orthorhombic cell change remarkably, and the superconducting properties are degraded.
Anisotropy of the Upper Critical Magnetic Field in Single Crystal YBa2Cu3O7+y
Authors: Hidaka Yoshikazu , Enomoto Youichi , Suzuki Minoru , Oda Migaku , Katsui Akinori , Murakami Toshiaki
Published: November 2005

The upper critical magnetic field H
c2 was measured on single crystals of the recently-discovered superconducting YBa2Cu3O7+y
oxide. The H
c2 along the basal plane is estimated to be larger than that along the c-axis by a factor of 5. A small anisotropy of H
c2 in the basal plane is also found. It is not clear at present whether this small anisotropy is intrinsic or due to crystal imperfectness such as micro-twinnings.
Transmission Electron Microscope Studies on High-Tc Superconductor Ba0.7Y0.3Cu1Ox
Authors: Ikeda Shozo , Hatano Takeshi , Matsushita Akiyuki , Matsumoto Takehiko , Ogawa Keiichi
Published: November 2005

Suscessful electron microscope observation was made for samples prepared by ion milling. Energy dispersive X-ray analysis showed that the composition of dominant phase was 18% Y, 29% Ba and 53% Cu in metal atoms. Plate like twins were observed in this phase; the twinning planes are {110} and the shape of twins is lenticular. This observation suggests that twins were induced mechanically to save the elastic energy produced during the phase transformation. Dislocations were also frequently observed in the phase. The directions of Burgers vectors are most likely to be 100 and 010.
Growth of (La1-xSrx)2CuO4-δ Crystals from High Temperature Solution
Authors: Inoue Tetsuo , Hayashi Shigeyuki , Komatsu Hiroshi , Shimizu Makoto
Published: November 2005

(La1-x
Sr
x
)2CuO4-δ single crystals (about 2.5×2.5×0.2 mm3 in the maximum size) were grown from high temperature solution, which was prepared by dissolving (La0.9Sr0.1)2CuO4-δ compound (50 wt.%) in CuO (50 wt.%) at about 1160°C.
Preparation of High-Tc Y-Ba-Cu-O Superconductor
Authors: Kawai Tomoji , Kanai Masaki
Published: November 2005

High-T
c Y-Ba-Cu-O superconductors were prepared by coprecipitation and noncoprecipitation solid diffusion methods. The electrical resistivities against temperature were compared for these preparation methods.
Large Exchange Enhancement of Electron-Phonon Coupling as a Possible Mechanism of High Tc Superconductivity
Authors: Kim Duk Joo
Published: November 2005

We discuss on the roles of the exchange interaction between electrons and the nature of the bare ion-ion interaction, besides the Fermi surface nesting, in making the electron-phonon coupling λph large. We discuss under what condition, λph can be strongly exchange enhanced and how such condition is fulfilled in the high T
c oxide superconductors. Also we show how the spin fluctuation coupling destructive to superconductivity might be neglected despite such exhange effect in λph.
High Tc Superconductivity of Y-Ba-Cu-O Ceramics
Authors: Kobayashi Masanobu , Satoh Hosaku , Ayusawa Kazutoshi , Abe Hitoshi , Tsuruoka Taiji , Ajioka Tsuneo , Shibata Susumu , Kawamura Kazutami , Nihei Kohji
Published: November 2005

The superconductivity and structure was studied in Y-Ba-Cu-O ceramics. BaCO3, Y2O3, CuO were mixed at a composition of YBa2Cu3O6.5, calcined at 900°C for 5 h, and sintered under various conditions. The critical temperature was 90 K for the ceramic sintered at 950°C for 10 h. The structure was analyzed with scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy.
Upper Critical Field of High Tc Superconductor Y0.4Ba0.6CuO2.22
Authors: Kobayashi Norio , Sasaoka Takaaki , Oh-ishi Katsuyoshi , Kikuchi Masae , Furuyama Masafumi , Sasaki Takako , Noto Koshichi , Syono Yasuhiko , Muto Yoshio
Published: November 2005

The upper critical field of Y0.4Ba0.6CuO2.22 has been studied by the electrical resistivity measurement in the magnetic field up to 23.4 T. The transition temperature was given to be 89.8 K for the midpoint of the resistive transition with ΔT
c=3.7 K. The slope of the critical field was -1.6 T/K. The upper critical field H
c2(0) was estimated to be 96 T according to the Werthamer, Helfand and Hohenberg expression for dirty limit. It is expected that the resistivity does not appear up to 61 T at 0 K in the framework of the BCS-WHH theory.
Novel Ferroelectricity in Fluorinated Ferroelectric Liquid Crystal
Authors: Yoshino Katsumi , Ozaki Masanori , Taniguchi Hiroki , Ito Masanori , Satoh Kazuo , Yamasaki Noritsugu , Kitazume Tomoya
Published: November 2005

Ferroelectric liquid crystals with spontaneous polarization exceeding 10-7 C/cm2 have been prepared by introducing a fluorinated carbon. The liquid crystals show anomalous dielectric behaviour due to the wall and field effects.
High Resolution Transmission Electron Microscopy of Defects in High Tc Superconductor Ba2YCu3Oy
Authors: Matsui Yoshio , Takayama-Muromachi Eiji , Ono Akira , Horiuchi Shigeo , Kato Katsuo
Published: November 2005

Defects in high-T
c superconductor Ba2YCu3O
y
, where y varies from 5.8 to 6.5, are examined by high resolution transmission electron microscopy (400 kV). Two kinds of planar defects are observed and they are considered to be formed by an insertion of additional metal and oxygen layers;
1) near CuO1-x
layers between two BaO layers, or
2) in the region near Y layers.
Weak diffuse electron scattering, which is possibly related to the short range ordering of oxygen vacancies in CuO1-x
layers, is also observed in a h
k
O reciprocal lattice section.
Complex Susceptibility of La1.9Sr0.1CuO4-δ
Authors: Mazaki Hiromasa , Takano Mikio , Kanno Ryoji , Takeda Yasuo
Published: November 2005

The response of superconducting La1.9Sr0.1CuO4-δ against a small ac magnetic field is studied in terms of complex susceptibility χ=χ'-iχ''. The superconducting transition shows two types of characteristics: One is insensitive to the change in the amplitude h
0(5-1000 mOe) of the external ac field, and the other is very sensitive to it. In the latter case, the transition width is appreciably broadened and the peak height of χ'' is enhanced as h
0 increases. Besides, no frequency dependence is found below 500 Hz. These behaviors are qualitatively similar to that of the multiconnected network consisting of weak-link junctions.
Effect of Concentration Ratio and Preparation Process on the Superconducting Properties of the Y-Ba-Cu-O System
Authors: Murakami Masato , Teshima Hidekazu , Morita Mitsuru , Matsuda Shoichi
Published: November 2005

We report the effects of concentraion ratio and preparation variables on the superconducting properties of the recently discovered Y-Ba-Cu-O compounds with transition temperatures greater than 90 K. We also report identification of the phase we believe responsible for the superconducting behavior.
Probing Magnetism of High-Tc Superconductor Y-Ba-Cu Oxide by Positive Muons
Authors: Nishida Nobuhiko , Miyatake Hideaki , Shimada Daisuke , Hikami Shinobu , Torikai Eiko , Nishiyama Kusuo , Nagamine Kanetada
Published: November 2005

Magnetic properties of a newly discovered high-T
c superconductor, Y-Ba-Cu oxide, were studied by zero-field positive muon spin relaxation method in a zero external magnetic field. Some kind of a magnetic phase transition was found at a temperature between 10 K and 27 K. It is discussed how this magnetism relates to the superconductivity.
High Field Properties of Superconducting YxBa1-xCu-Oxides
Authors: Noto Koshichi , Morita Hiroaki , Watanabe Kazuo , Murakami Yoshitake , Fujimori Hiroyasu , Kobayashi Norio , Muto Yoshio
Published: November 2005

The transition temperature, T
c, the upper critical field, H
c2(T), and the critical current density, J
c(H), at 4.2 K have been studied in high-T
c Y
x
Ba1-x
Cu-Oxide system. Two maxima in T
c around x=0.33 and 0.4 have been observed. The slope dH
c2
mid/dT near T
c for the sample x=0.4 is -1.5 T/K, resulting in H
c2 at 0 K higher than 85 T by an extrapolation according to the WHH theory. Although the J
c value of ∼3.5 A/cm2 at 15 T is very low, it decreases only 10% even at 27 T, showing high potential for practical use at high fields when J
c is raised by the introduction of strong pinning centers in this material.
Anomalous Resistivity in Ba-Y-Cu-O Systems
Authors: Oda Yasukage , Kohara Takao , Nakada Ichiroh , Fujita Hiroshi , Kaneko Tetsuyuki , Toyoda Haruhisa , Sakagami Eiji , Asayama Kunisuke
Published: November 2005

Anomalous temperature dependence of the resistivity was observed in Ba-Y-Cu-O systems whose starting composition is different from the Ba, Y, Cu ratio of 2:1:3. It may be attributed to an occurrence of partial superconductivity with higher transition temperature than 90 K, or a semiconductor-metal transition.
Preparation and High Tc Superconductivity of Ba-Y-Cu Oxides
Authors: Ohta Masatsune , Takahashi Koh , Okai Bin
Published: November 2005

High T
c superconductors of monophase, Ba2YCu3O8-x
, and mixed phase samples were prepared from mixtures with Ba/Y/Cu ratios of 2/1/3 and 2/1/3.5, respectively. They were investigated by dc electrical measurements and X-ray diffraction. All samples have basically an orthogonal structure. The zero-resistivity temperatures for the monophase and mixed phase samples were 86 K and 77 K, respectively. The reason for the different superconducting characteristics is also discussed.
Effect of Pressure on Superconducting Transition Temperature of Y0.4Ba0.6CuOy
Authors: Kai Bin , Takahashi Koh , Ohta Masatsune
Published: November 2005

Superconducting transition temperatures were measured under pressure for Y0.4Ba0.6CuO
y
specimens. The onset temperature T
co increases with the increase of pressure at the rate of 0.45 deg/GPa, whereas the behavior of complete temperature T
cf is more complicated; at first it increases and then above 10 GPa it decreases. Residual resistance remained without disappearing even below T
cf with specimens put under stress.
High Tc Superconductivities of A2Ba4Cu6O14+y
Authors: Tsurumi Shigeyuki , Hikita Makoto , Iwata Tsunekazu , Semba Kouichi , Kurihara Susumu
Published: November 2005

Superconductivities of A22Ba44Cu6O14+y
(0<y<2.5, A = lanthanides except for Pm) compounds are studied through X-ray powder diffraction pattern analysis and electrical resistance measurement. Resultant compounds in case of A = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm and Yb except for Ce, Pr, Tb and Lu exhibit both characteristic diffraction patterns for A2Ba4Cu6O14+y
, i.e., oxygen defect perovskite (GDP) and superconducting state. Key structure for realizing high Tc more than 90 K and narrow transition width is confirmed to be related with the GDP phase.
Effect of Hetero-Valent-Ion Doping in the High Tc Y-Ba-Cu-O Superconductor
Authors: Uwe Hiromoto , Motoi Yuichi , Yamaguchi Hirotaka , Sakudo Tsunetaro
Published: November 2005

Effect of hetero-valent-ion (Ce and La) doping on the resistive transition of the high T
c superconductor Y0.33Ba0.67CuO
n
or Y0.37Ba0.63CuO
n
has been investigated. The midpoint of the resistive transition is found to decrease and the width to increase, with increase of the doping. Unstable resistive anomaly at a higher temperature is also observed.
Persistent Current in Y-Ba-Co Oxides Superconductor at Liquid Nitrogen Temperature
Authors: Yamada Tadatoshi , Morita Masao , Yokoyama Shoichi , Yamamoto Shunji , Iwamoto Masatami , Yoshizaki Kiyoshi , Wakata Mitsunobu , Hujiwara Fumio , Kubo Yoshio , Miyashita Shoji , Matsuno Shigeru , Nagai Takayuki , Hashimoto Yasuo
Published: November 2005

The bulk specimens of (Y1-x
Ba
x
)3Cu3O8-δ, x=0.5∼0.73 were prepared from oxide and carbonate powder mixtures. Critical temperature was higher than 90 K in the four-probe method. Critical current, 113 A/cm2 was also obtained in the same method at liquid nitrogen temperature and zero external field. Persistent current was proved at liquid nitrogen temperature.
Pressure Effect on the Superconducting Transition Temperature for (YxBa1-x)CuO2.3 Compound System
Authors: Yoshida Hajime , Morita Hiroaki , Noto Koshichi , Kaneko Takejiro , Fujimori Hiroyasu
Published: November 2005

The presure effect on the superconducting transition onset temperature (T
co) and complete transition temperature (T
cf) was measured for the compound (Y
x
Ba1-x
)CuO2.3 with x = 0.325, 0.35 and 0.425. Both T
co and T
cf increase with increasing pressure. The values of dT
co/dP and dt
cf/dP are in the range of 0.09 to 0.17 K/kbar and 0.20 to 0.40 K/kbar, respectively. These values decrease with increasing the concentration x.
Characterization and Critical Current Density Determination of High-Tc Superconductor Ba-Y-Cu Oxide
Authors: Hioki Tatsumi , Oota Akio , Ohkubo Masataka , Noritake Tatsuo , Kawamoto Jun-ichi , Kamigaito Osami
Published: November 2005

X-ray diffraction is used to characterize a sintered specimen of Ba-Y-Cu oxide which has zero resistance below 91 K and a diamagnetic susceptibility, χ, as large as 43% of the perfect diamagnetism at 84 K. About 90% of the specimen volume is found to be Ba2YCu3O
x
. The critical current densities under zero applied magnetic field are measured to be 105 A/cm2 at 77 K and 300 A/cm2 at 4.2 K. The influence of machining of the specimen on χ is investigated. Pulverization of the sintered bulk reduces χ/(-1/4π) from 43% to 14% at 84 K. This reduction is recovered by a subsequent thermal annealing.
Crystal Structures of YBa2Cu3Ox and LnBa2Cu3Ox (Ln = Ho and Dy)
Authors: Onoda Masashige , Shamoto Shin-ichi , Sato Masatoshi , Hosoya Syoichi
Published: November 2005

Structure determinations of YBa2Cu3O
x
and LnBa2Cu3O
x
(Ln = Ho and Dy) are carried out by single crystal X-ray diffraction. The x values obtained in the present analyses are about 6.0, 6.0 and 6.25 for Y, Ho and Dy compounds, respectively and they have tetragonal structure with space group P4/m
m
m. The structures are perovskite-related ones with the c axis triplicated due to the ordering of Ba and Y or Ln. All oxygen atom sites around Y or Ln atoms in the c plane are vacant. Almost all oxygen atom sites in the layers which contain the Cu(1) sites (4/m
m
m) are also vacant. The present YBa2Cu3O6 crystal is found to be a semiconductor, which indicates the importance of the oxygen number for the occurrence of superconductivity in Y-Ba-Cu-O and Ln-Ba-Cu-O systems.
A New Analytical Model for Spin Coating Process with Solvent Evaporation
Authors: Shimoji Sadao
Published: November 2005

The effect of solvent evaporation on the film thickness produced by the spin-coating process is expressed as a function of concentration of solvent. This function is inserted into the equation for the film thickness. The equation obtained gives its analytical solution, which depends on time and the concentration. The concentration is obtained from the diffusion equation. Thus, a more detailed analysis of solvent evaporation becomes possible than before. As an application, the experimental dry film thickness of Jeneckhe is analyzed and a comparison is made with his model.
SiO2 Thin Film Prepared from Si3H8 and O2 by Photo-CVD Using Double Excitation
Authors: Okuyama Masanori , Fujiki Noriaki , Inoue Kohji , Hamakawa Yoshihiro
Published: November 2005

Silicon dioxide thin films have been prepared at low temperatures from 25 to 390°C from Si3H8 and O2 gases by photo-CVD using the double excitation of VUV light from a D2 lamp and UV light from a Hg lamp. Growth rate is ∼150 Å/min at 25°C and decreases as the substrate temperature increases. The amount of Si-H and Si-OH, and the fixed-oxide-charge also decrease as the temperature increases. The film deposited at 260°C shows small interface state density and the minimum is 3.6 × 1010 cm-2eV-1 near the midgap.
Arsenic Pressure Dependence of Interdiffusion of AlGaAs/GaAs Interface in Quantum Well
Authors: Furuya Akira , Wada Osamu , Takamori Akira , Hashimoto Hisao
Published: November 2005

Arsenic pressure dependence of interdiffusion of AlGaAs/GaAs hetero-interface at a high temperature has been studied by masuring the wavelength shift of photoluminescence in a multi quantum well. It was found that the interdiffusion at the temperature of 850°C was minimized under arsenic pressure of 100 Torr and it was enhanced both under the lower and higher arsenic pressure. Also the degradation of photoluminescence intensity was observed only under the higher arsenic pressure. These properties are considered to be caused by excess vacancies of gallium and aluminum, and their assosiated defects.
Capless Rapid Thermal Annealing of Silicon Ion Implanted Gallium Arsenide
Authors: Hara Tohru , Gelpey Jeffrey C.
Published: November 2005

Argon arc lamp rapid thermal annealing of ion implanted gallium arsenide (GaAs) has been studied. Silicon ion was implanted into semi-insulating GaAs at 120 keV with a dose of 3×1012 cm-2. Capless annealing was performed by dc argon arc lamp at temperatures of 850-1000°C. Carrier concentration profiles are abrupt at the interface and fit well with the LSS profile. Abruptness of the profile was 0.78 at 850°C for 15 s and at 1000°C for 2 s, where the abruptness was defined as 1.0 in LSS theoretical profile and a lower value shows a gentler profile. This value is much greater than that by tungsten-halogen lamp rapid thermal annealing of 0.36 and furnace annealing of 0.34. This annealing technique is useful for the formation of a shallow channel layer with abrupt·carrier concentration profile for GaAs MESFET's.
Tunable VUV Generation by Anti-Stokes Stimulated Raman Conversion of XeCl Laser Radiation
Authors: Takahashi Akihiko , Matsumoto Osamu , Maeda Mitsuo , Miyazoe Yasushi
Published: November 2005

This paper reports on the results of experiments into efficient higher-order anti-Stokes Raman conversion of tunable short-pulse XeCl laser radiation. The maximum output energy of the pumping laser, in which the radiation of a frequency-doubled dye laser is amplified by two XeCl laser amplifiers, is 55 mJ with a pulse duration of 1 ns FWHM. Using hydrogen gas as a Raman medium, a series of anti-Stokes lines up to the 12th order (121.5 nm) is generated in the vacuum ultraviolet (VUV) region.
A New Position Alignment Method in Electron-Beam Direct Writing Lithography Using the SEM
Authors: Park Sun-Woo , Shono Katsufusa , Dumin David J.
Published: November 2005

A new alignment method for direct writing using an electron-beam is described. The alignment mark corresponding to the unit cell of the bit-map CAD system is defined in the poly-Si layer. The alignment marks consist of array and chip marks. The alignment method consists of two steps of two dimensional displacement and rotation of the coordinate axis. The marks are directly recognized by searching for the alignment marks on the CRT of SEM. NMOS IC test devices were fabricated on a Si wafer employing this alignment method. The alignment mistolerance between each pattern layers was less than 1 µm under the 6 µm design rule.
Proposed Modulator for Global VLSI Optical Interconnect Network
Authors: Bradley E. , Yu P. K. L.
Published: November 2005

An optical absorption modulator which reflects the incident radiation instead of transmitting it, and doubles the absorption path length in doing so, is suggested. The usefulness of such a configuration is demonstrated by outlining a global optical interconnect network for VLSI circuits, which can be implemented if such a modulator is available.
Growth of ZnSe-ZnS Strained-Layer Superlattices by Metallorganic Molecular Beam Epitaxy
Authors: Taike Akira , Teraguchi Nobuaki , Konagai Makoto , Takahashi Kiyoshi
Published: November 2005

Metallorganic molecular beam epitaxial (MOMBE) growth of ZnSe-ZnS strained-layer superlattices (SLS) on (100) GaAs substrates has been demonstrated for the first time. Diethylzinc, diethylselenide and diethylsulphide were used as source gases and pyrolysis of DESe and DES was carried out in cracking cells. The satellite peaks observed by X-ray diffraction measurements are indicative of superlattice structures. Photoluminescence spectra of SLS measured at 4.2 K showed blue emission originating from the recombination of electron-hole pairs between the quantized levels in ZnSe well layers.
Complexes of Nitrogen and Point Defects in Silicon
Authors: Suezawa Masashi , Sumino Koji
Published: November 2005

The effect of electron-irradiation is investigated on the optical absorption in nitrogen-doped Si. Two absorption peaks that have been ascribed to pairs of nitrogen atoms are found to split each into two peaks due to electron-irradiation. One of the two peaks after the splitting of each peak is attributed to the absorption due to vibration of an ordinary nitrogen atom-pair and the other to that of a complex consisting of a nitrogen atom-pair and a single vacancy.
Frequency Dependence and Mechanism of Electroluminescence in ZnS (Cu, Al) Electroluminescent Phosphors
Authors: Miyashita Kazuo , Wada Masanobu , Takahashi Tadashi
Published: November 2005

First, it is confirmed that the empirical equation B=B
0 exp
(-C/√V) is applicable to the electroluminescent emission from ZnS (Cu, Al) EL phosphors embedded in a dielectric. Then, based on this equation, the frequency dependence of the electroluminescent emission is discussed in detail. The quantities B
0 and C in the above equation are considered with respect to frequency and temperature. According to the experimental results obtained, the emission mechanisms of electroluminescence in this phosphor are considered, principally on the exciting high field, the primary electron source and the recombination process. Finally, it is concluded that primary electrons may be injected through the depletion layer by the tunnel effect and that the recombination process may act on the monomolecular law.
A New Definition of Information Volumes on Radiographs from Density-to-Thickness Curves
Authors: Kanamori Hitoshi
Published: November 2005

In order to develop information-radiography, a definition of information volume is given with respect to the information of contrast due to test-pieces on an object having a wide thickness-range. Among the density-to-exposure curves which passes the same end-points, the linear one has maximum information. A contrast-deficient radiograph has more information than an excessively contrasted radiograph, since the former represents the entire thickness-range. The information volumes thus defined gives radiographic effects due to the combination of equipment, exposure-factors, and objects. Some numerical examples are included.
Quantum Theory of Negative Energy in Microwave Tubes
Authors: Dodo Taro
Published: November 2005

Using the procedure of the “quantum theory of field”, the following result is derived rigorously; when a medium moves faster than the wave velocity, the quantum of wave propagating opposite to the movement of the medium has negative energy.
Dielectric Properties and DC Conductivity of Vacuum-Deposited SiO Films
Authors: Hirose Hidenori , Wada Yasaku
Published: November 2005

Dielectric properties from 10-2 to 107 c/s and dc conductivity are investigated for vacuum-deposited SiO films. The conductivity decreases with increasing oxidation and the activation energy is estimated to be 8.6 kcal/mole. Two dielectric dispersions are found, the loss peaks of which are at 10-1 c/s (1f dispersion) and at above 107 c/s (hf dispersion), respectively. The strength of 1f dispersion decreases with increasing oxidation and metallic impurities have no appreciable effect on the dispersion. The activation energy of 1f dispersion is almost equal to that to dc conduction. The dc conduction and 1f dispersion are concluded to be attributed to diffusion of free Si ions. The hf dispersion is ascribed to local torsional vibration of SiO chains. A model of the molecular structure of SiO in the glassy state is suggested, which is well consistent with the electrical and optical properties of this material.
Study on Precipitates in Oxygen-Doped Silicon Single Crystals by X-Ray Diffraction Micrography
Authors: Furusho Katsuhisa
Published: November 2005

The effects of heat-treatments on oxygen-doped silicon single crystals were studied by X-ray diffraction micrography using extinction contrast. For silicon crystals of 1×1018 atoms/cm3 oxygen-concentration, characteristic intensity increase were observed after heat-treatment at 1000°C for several hours, and individual images were resolved after heat-treatment at 1200°C for a few fours. From variation in the shape of images with diffracting planes, it was concluded that the images were due to the disc-shaped precipitates of silicon oxide parallel to {111} planes.
X-Ray Spectroanalysis of Light Elements Using H3/Zr as Exciting Source
Authors: Tanemura Takashi
Published: November 2005

The capability of a device for the X-ray spectroanalysis is studied which essentially consists of a H3/Zr source, a helium-filled specimen chamber and a proportional counter equipped with a thin plastic window. The best results can be obtained with a 0.46 mg/cm2polycarbonate window which allows the transmission of soft X-rays below 1 keV but stops the β-rays emitted from the source and scattered towards the window. It is shown that both the X- and β-rays from the H3/Zr source are effective in exciting the characteristic X-rays of light elements (Na, Mg, Al and Si) and the X-rays from the source are effective in exciting those of elements of intermediate atomic numbers (Ti, V, Cr, Mn, Fe Co and Ni). The K X-ray intensities for light elements are comparable to or higher than those for elements of intermediate atomic numbers. Two examples are given which illustrate the usefulness of this device in the X-ray spectroanalysis of light elements.
Some Characteristics of a Pulsed Probe RF Ion Source
Authors: Suganomata Shinji
Published: November 2005

A pulsed beam up to 1mA was obtained by applying pulsed voltage to the probe the RF ion source. The operating characteristics of the source were examined. The required probe voltage depends upon the rise time of the voltage pulse, and the delayed response of the beam pulse to the voltage pulse has been observed. A qualitative interpretation of the experimental results is given.