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Volume 44, Issue 2
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[in Japanese]1997 Volume 44 Issue 2 Pages 126
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (76K) -
Shingo Kaimori, Shuji Kawasaki, Masaki Azuma, Mikio Takano1997 Volume 44 Issue 2 Pages 127-131
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSLa2CuSnO6, even though it contains CuO2 layers, does not exhibit superconductivity. It might result from the in-plain Cu-O bond length being too long(about 2.0 Å, compared with 1.9 Å of La2CuO4). So, we replaced La with smaller atoms Pr, Nd, Sm, expecting that these might contract the CuO2 layers and lead to superconductivity. For synthesis we used high pressure(6Gpa for Pr, Nd and 8Gpa for Sm). The result Is that, contrary to our wish, the CuO2 layers buckled even more seriously and the Cu-O bond did not get shorter. In this paper, we focused on the magnetism of Ln2CuSnO6(Ln=La, Pr, Nd). In the temperature range of 150 to 350K, these compounds showed almost the same characteristics which have been explained assuming spin-canted weak ferromagnetism. However, Pr2CuSnO6and Nd2CuSnO6exhibited ferromagnetic behavior at lower temperature suggesting ordering of the Pr3+(Nd3+)moments. Antlferromagnetic coupling between the weak ferromagnetic CuO2 layers and the ferromagnetic LnO layers has also been suggested.View full abstractDownload PDF (362K) -
Shinichi Kikkawa, Noriko Taya, Fumikazu Kanamaru1997 Volume 44 Issue 2 Pages 132-136
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPreparation and oxygen doping of La2Can-1 CunO2n+2 were investigated by applying soft chemical methods. Mixed aqueous solution of La, Ca and Cu acetates was titrated with tartaric acid aqueous solution. La2CaCu2O6(n=2) could be obtained by firing the coprecipitates even at 800°C because of their homogeneously mixed state in the precipitates although the same compound had been prepared above 1000°C by solid state reaction. Both La2Ca2Cu3O8 (n=3) and La2Ca3Cu4O10 (n=4) could be firstly obtained at 700°C in the similar preparation method under ambient pressure. They were not stable above 800°C to decompose into mixtures of La2CaCu2O6 and small amount of other compounds. Porous sintered body of La2CaCu2O6 with relative density of about 15% was obtained by this preparation method. It could be effectively oxygen-doped by electrochemical method. The product showed a presence of superconducting phase with Tc around 30K.View full abstractDownload PDF (280K) -
Atsuyoshi Inoue, Masato Kakihara, Minoru Osada, Shinjirou Tochihara, H ...1997 Volume 44 Issue 2 Pages 137-141
Published: February 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSHigh-purity polycrystalline samples of Bi2.1Sr1.9-xLaxCuO6+d with x=0-1 have been prepared by the polymerized complex method X-ray powder diffraction and complex magnetic susceptibility mesurements have shown that the samples are of a single-bulk Bi2201 phase without any impurity such as Bi17Sr16Cu7Oy, CuO, Bi2Sr3Cu2Oy, The dependence of the superconducting transition temperature Tc(onset) with increasing La content has a parabolic-like behavior with maximum Tc(onset)=16.6 K at x=0.3. We heve investigated the effect of La substitution for Sr on Raman spectra of Bi2.1Sr1.9-xLaxCuO6+d. The apical-oxygen phonon at-630cm-1 softens by -20cm-2 with increasing La content, when x goes from 0 to 1. This change can be interpreted in terms of the charge redistribution induced by decreasing the Cu and Bi valences with La doping.View full abstractDownload PDF (310K) -
Masashi Fujiwara, Mokoto Nakanishi, Totsuo Fujii, Jun Takada, Yoshihir ...1997 Volume 44 Issue 2 Pages 142-146
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effects of electrochemical Li-doping on superconducting properties of the Bi-2212 phase have been investigated. The electrochemical Li-doping into the 2212 phase was first succeed with remaining the original crystal structure and without formation of any second phase. Maximum Li content y as LiyBi2Sr1.5Ca1.5Cu2Oz by this electrochemical reaction was found to be 0.37. The Li content increased with increasing in reaction time and applied potential. The lattice parameters (a, c) of the Bi-2212 crystals increased continuously from (5.397Å, 30.69Å) for y=0.0 to (5.411Å, 30.89Å) for y=0.37. Tc of the doped samples continuously decreased to OK for around y=0.27.View full abstractDownload PDF (283K) -
Nobuyoshi Takabatake, Etsuro Sugimata, Tatsuhiro Tachibana, Wataru Mur ...1997 Volume 44 Issue 2 Pages 147-151
Published: February 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe electrochemical reduction was applied to porous Bi-Cu system superconductor in 0.05N:Ca⋅(NO3)2⋅4H2O, 0.03N:Sr(NO3)2, 0.05N:Pb(NO3)2, 0.05N:Cu(NO3)2⋅3H2O in methanol using platinum as the counter electrode. Changes in crystal phase and morphology by electrochemical treatment were investigated by XRD, Tc, oxygen content by iodometric titration and SEM method. Tc(onset) of the sample of the 30Å phase treated electrochemically in Ca2+ solution was highest, and enhansed by 9K, but that of the 37Å phase being decreased. The oxygen content was decreased by 0.14 maximumly, and the c lattice constants were stretched a little except in Cu2+ Solution. In the SEM observation, the reaction proceeded to the inner part of sample except in Cu2+ solution. Then this reaction is considered to be a reduction in which deposited particles react with oxygen atoms in the samples and followed by stretching of the c lattice constants. It was found that a the sample of the 30Å phase could be reduced in liquid phase as well as in gaseous phase.View full abstractDownload PDF (3629K) -
Preparation of Bi-system Superconducting Film by Metalorganic Deposistion and their Epitaxial GrowthNobuyoshi Takabatake, Tatsuhiro Tachibana, Wataru Muramoto, Kentaro Oh ...1997 Volume 44 Issue 2 Pages 152-157
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBi-Pb-Sr-Ca-Cu-O superconducting films were prepared by metalorganic deposition on single LaAIO3(100) substrates using acetate solution of starting composition Bi2.46Pb0.74Sr2.0Ca2.2Cu3.2Oy. The films were prepared by repeating the process of coating and decomposition( at 700°C for 30 min ) 5 times and finally sintering at 855°C for 12 hours. The values of Tco and Jc of 1.5 μm thick films were 98K and 1.2×104A/cm2(64K, OT) respectively. The result of x-ray pole figures has shown that these films were epitaxial through a good lattice match of LaAlO3 substrates. ICP analysis showed that mole ratio of Pb was lower than 0.1 in the film on MgO(as mole ratio of Cu=3.2).View full abstractDownload PDF (2209K) -
Kunio Matsuzaki, Akihisa Inoue, Tsuyoshi Masumoto1997 Volume 44 Issue 2 Pages 158-161
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe role of Ag sheath on the formation of a 2223 phase in Ag-sheathed Bi-Pb-Sr-Ca-Cu oxide tapes was investigated. It was found that the Ag sheath promoted the formation of the 2223 phase through the extension of the temperature range between its partial melting and decomposition as well as through the ease of the control of the atomosphere in the Ag sheath. Furthermore, the Ag sheath was recognized to act as an effective substrate for the formation of the well-developed texture structure.View full abstractDownload PDF (1894K) -
Yuji Noguchi, Masasuke Takata1997 Volume 44 Issue 2 Pages 162-167
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe have proposed the new method for measuring transport critical current density Jct of high-Tc polycrystalline superconductors on the basis of the exponential critical-state model Jct=J0 exp(- Binter/B0), where J0 and B0 are constant, andBinter is intergrain magnetic-flux density. Full-penetration field Hp and remnant-magnetization saturating field H6 are measured directly from the magnetization hysteresis and the remnant-magnetization curve of the sample, respectively. The model parameters J0 and B0 are derived by substituting Hp and Hs into critical-state equations. A critical current density measured by four-probe method is averaged one of local Jct over the sample exposed to self magnetic field generated by applied current, and increases with decreasing the cross-sectional area of the sample, while the intrinsic property of local Jct can be estimated by the method proposed in this work.View full abstractDownload PDF (335K) -
Shinjiro Tochihara, Hiroshi Yasuoka, Hiromasa Mazaki1997 Volume 44 Issue 2 Pages 168-172
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWe modified the Bean critical-state model by taking into consideration the surface barrier and the lower critical field of type-II superconductors. In the framework of this modified Bean critical-state model, we have calculated the initial magnetization curves and full hysteresis loops for an infinitely long cylinder immersed in an external ac field superimposed on a dc bias field. Through the computed M(H) curves, we give some discussion on the effect of A H and Hc1 to the initial magnetization and the temperature dependence of hysteresis loops of type-II superconductors.View full abstractDownload PDF (261K) -
Katsuyoshi Hotta, Hajime Miyazawa, Yoshinori Miyazawa, Masao Murakawa, ...1997 Volume 44 Issue 2 Pages 173-176
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA study on connecting superconductors of Y system 123 phase through the laser irradiation treatment has been conducted. Superconductive powder of the identical phase pasted with a mixture of organic binder and solvent were filled as a medium between the two pieces of the superconductive bulk installed on a jig system, and which were set on a X-Y table to be irradiated by CO2 laser accompanied by oxygen gas blow along its contact line under the conditions : laser output power 260-320 W at defocus distance of focal point 120 mm, assist gas pressure 98-294 kPa, beam scan speed 1-8 mm/min, and beam scan times 1-3 strokes.
The results indicated that the electric resistance was almost constant before the laser irradiation but 57.9 K as Tc(and) was obtained for the certain samples when blown with a great deal of oxygen gas at low speed beam scans at the laser irradiation. SEM image and EPMA mapping after the laser irradiation showed that the superconductive bulk and the paste were connected successfully.View full abstractDownload PDF (2394K) -
Tetsuo Kato, Noriyoshi Kurata, Yufen Bao, Katsushi Kusaka1997 Volume 44 Issue 2 Pages 179-184
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSOn the sintered 12.5 percent chromium-iron magnetic alloy added Fe-P powder from 0.4 to 1.2 percent, the change in the magnetic properties with the sintering time at 1200°C was mainly studied in making use of the EPMA mapping analysis . After sintering for 1 hour, DC and AC magnetic properties come to the maximum value by the addition of 0.6 and 0.8 percent Fe-P respectively. The sintered density increases with the increasing of sintering time and DC magnetic properties increase monotonously in the same way. However, AC magnetic properties show a specific inclination to firstly increase and then decrease with sintering time. It was comfirmed by the EPMA mapping analysis that these changes in the magnetic properties originate from the phenomena of the liquid phase sintering, the solid solution of P and its remaining at the grain boundaries caused by Fe-P addition of over 0.8 percent.View full abstractDownload PDF (3917K) -
Tool Shape and Roughness of Finished SurfaceEiichi Sentoku, Hiroshi Tanaka, Hiroshi Kawabata1997 Volume 44 Issue 2 Pages 185-189
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn recent years, ceramics for a few mechanical and electronic parts are performed on the cutting process of the green-compact. The residual crack on the finished surface is influenced the strength of the ceramics after the sintering. The purpose of this paper is to clarify the cutting performance of the ceramics green compact that used the alumina of the grain size 0.2 μ m. The machining performance of alumina green-compact is discussed from view point of the relation between the shape of tool edge and the surface roughness on the workpiece. In the cutting test by turning, the cutting condition is cutting speed 100m/min, feed 0.1mm/rev, depth of cut 0.2mm. The tool shape on the insert tip are made chamfer angle from -25°to 5° The main results obtained are follows:(1) The surface roughness in feed direction and the in circumference direction was existed an correlative. (2)In the chamfer angle -10°on the tool edge, the surface roughness at cutting could give rise to Rmax 4.0 μm. (3)The tool life of this cutting was lager than other cutting.View full abstractDownload PDF (2497K) -
Rieko Yaguchi, Eiji Kamijo1997 Volume 44 Issue 2 Pages 190-193
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAlN ceramic is used as the package material instead of Al2O3 for microelectronics application fields because having high thermal conductivity, thermalstabi1ity, thermal expansion coefficient same as silicon high electrical resistance, low dielectric constant and so on. It is difficult to make a metallizing layer because of AlN is covalent bonded compound. We tried todeposit a copper film with RF sputtering method on to an oxidized top surface with ionic bonded Al2O3 ultra thin layer on AlN ceramic, and measured the adhesion.
The samples which were processed in the oxidation for 5 hour in air at 1173K gave a maximum value, 956 kg/CM2, in the adhesion. The decrease of the heat resistance by the oxidation process was not observed.View full abstractDownload PDF (2463K) -
Takashi Murakami, Akio Saito, Akira Kitahara, Yasuharu Shirai, Haruyuk ...1997 Volume 44 Issue 2 Pages 194-197
Published: February 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe intermetallic compound Nb3Al has attracted much attention as a potential high temperature material because of its high melting point. In the present study, we have made shock-consolidation experiments on Nb-20at. %Al alloy powders, which is produced by mechanical alloying of elemental powders, with the use of a single-stage propellant gun as a function of projectile velocity in the range of 0.75-1.49km/s. The density of compacts increases with increasing projectile velocty and saturates to a value of 7.25 Mg/m3 when the velocity exceeds 1.16km/s. X-ray diffraction analysis indicates that the compound Nb3Al is formed for projectile velocities greater than 1.16km/s. Very fine microstructures with grain size of 10-200nm as well as high hardness values are observed on compacts consolidated with these projectile velocities.View full abstractDownload PDF (2770K) -
Kenzo Fukaura, Hisakichi Sunada, Yoshihiko Yokoyama, Tomohiro Tsukaguc ...1997 Volume 44 Issue 2 Pages 198-201
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPure aluminum matrix composites reinforced with SiC particles were fabricated by powder metallurgy, which involves hot pressing. Effects of particles volume on hardness and wear resistance of composites were investigated. Hardness of composites proportionally increased with increasing volume fraction of particles and 30%SiCp/Al composite has maximum hardness and its hardness is 2.7 times greater than that of pure aluminum. Increasing the volume fraction of reinforcements was remarkably efficient for wearing at low and middle sliding speed. Wear surface observation shows that adhesive and abrasive wear occurred at low and middle sliding speed, and melt and seizure wear took place at high sliding speed.View full abstractDownload PDF (2853K) -
Kenzo Fukaura, Hisakichi Sunada, Yoshihiko Yokoyama, Kazushige Kidena1997 Volume 44 Issue 2 Pages 202-206
Published: February 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTwo kinds of CuO/Al composites and TiO2/Al composite were prepared by powder meturllagy involves hot pressing. Afterward, structures and hardness changes were investigated by means of Electron Probe Micro Analyzer, X-ray diffraction equipment and Vickers hardness tester.
In the case of 3mass%CuO/Al composites, CuO was deoxidized by aluminum during heating at 823K, as a result, Cu dissolved into aluminum matrix and CuO particles are gradually replacing Al2O3 particles on in-situ manner. Consequently Al2O3/Al composite was made and it revealed age hardning by isothermal heat treatment. On the other hand, 10mass%CuO/Al composite, intermetallic compound Al2Cu was formed in the matrix due to excessive amount of Cu atoms.
In the case of TiO2/Al composite, since Ti atoms diffused toward aluminum matrix, detrimental Al3Ti were formed in the aluminum matrix and at the same time TiO2 was transformed into Al2O3.View full abstractDownload PDF (4031K) -
Hisamichi Kimura, Kenichiro Sasamori, Wei Zhang, Akihisa Inoue1997 Volume 44 Issue 2 Pages 207-212
Published: February 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical grinding(MG) was performed for Al-Cr and Al-V based alloys by using the crushed powder of arc-melted Al94.5Cr3Ce1Co1.5, Al96V4Fe2, Al91V6Fe3 and Al88V8Fe4 alloys and the atomized Al96V4Fe2 powder. The shape, structure and thermal stability were examined on powder prepared by MG. The phase of Al94.5Cr3Ce1Co1.5 powder change in the order of Al+Al13Cr2→Al+icosahedral(I)→Al+I+amorphous(Am)→Al+Am by MG. The nonequilibrium icosahedral or amorphous and Al phases were found to be formed for the MG Al-Cr and Al-V base alloys with Al-rich compositions of 88 to 95%. The formation of the MG-induced nonequilibrium phases were easier for atomized powder than for the crushed powder.View full abstractDownload PDF (4083K)
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