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Volume 37, Issue 1
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[in Japanese]1990 Volume 37 Issue 1 Pages 2
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (87K) -
Takumi Minemoto1990 Volume 37 Issue 1 Pages 3-11
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThere are many kinds of image converters using Bi12SiO20 single crystal up to date. Also the possibility of applications has been described by man ?? workers. But, for the applications of the converters, there are many difficult problems to be solved. In this paper, the principles of the converters are explained together with interesting applications. And the problems to be solved are pointed out.View full abstractDownload PDF (466K) -
Norifumi Fujimura, Seiki Goto, Tokihiro Nishihara, Taichiro Ito1990 Volume 37 Issue 1 Pages 12-16
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSZinc oxide thin films were well known to grow parallel to the C-axis, a (002) oriented film, on various substrates. To utilize for the SAW (Surface Acoustic Wave) devices, a (110) textured and high resistivity films are necessary. By considering the binding style, the (110) oriented film devices could be obtained. In this paper, the resistivity controlling of ZnO films having the controlled texture to apply for the SAW filter and the transparent conducting film is discussed.View full abstractDownload PDF (231K) -
Masami Kakinoki, Kouji Ando, Norifumi Fujimura, Taichiro Ito1990 Volume 37 Issue 1 Pages 17-22
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSLithium niobate (LiNbO3) has a very large electro-optic coefficient of r33=30.8×10-12m/V, and is used as a substrate for the optical waveguide and the SAW (Surface Acoustic Wave) device. The LiNbO3 thin film is very useful for micro devices and hybridization of optical devices and electrical devices.
Lithium niobate thin films were prepared by a rf-magnetron sputtering method. Enough O2 gas pressure or enough power makes a single pahse LiNbO3. At the low O2 pressure or the low rf power, coexistence of LiNbO3 and LiNb3O8 was observed. The LiNbO3 grows epitaxially on a α-Al2O3 substrate. Crystallinity of an epitaxial LiNbO3 film on a C-cut α-Al2O3 is better than that on R-cut α-Al2O3. A lattice parameter (a-axis) of the epitaxial LiNbO3 film decreases 5% from the ordinary value. It makes the lattice mismatch decrease.View full abstractDownload PDF (4263K) -
Nobuyuki Hiratsuka, Tomonori Ichikawa, Kazuo Sugiyama, Mitsuo Sugimoto1990 Volume 37 Issue 1 Pages 23-26
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe amorphous film having no defect was homogeneous because it neither needed to heat a substrate at high temperature nor to anneal an as-grown film at high temperature. The magnetic properties of the amorphous oxide film with perpendicular anisotropy was M=80 emu/cc, Hc=0.6 KOe, squareness ratio=0.39 and Ku=1.8×105 erg/cm3 (1.8×104 J/m3). Dependence of Faraday rotation on wave length for the amorphous film showed that minus value of θF was less than 1300 nm and plus value of it was above 1300 nm. The maximum value of θF was -1.7×104 deg/cm at about 800 nm. Absorption coefficient was 72 dB/cm and figure of merit was 110 deg/dB at this wavelength. Its value of θF was smaller about one order than that of cobalt ferrite film.View full abstractDownload PDF (1170K) -
Yoshiyuki Sato1990 Volume 37 Issue 1 Pages 27-30
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSElectrochromic (EC) iridium oxide films were prepared by thermal oxidation of vacuumdeposited Ir-C films. The characteristics of thermally oxidized iridium oxide films (TOIROFs) were compared with those of anodically grown iridium oxide films (AIROFs) and of sputtered iridium oxide films (SIROFs). In brief, the characteristics of the TOIROFs are intermediate between those of AIROFs and SIROFs. The EC behavior of transmissive EC devices consisting of an amorphous WO3 film, nonaqueous electrolyte (propylene carbonate solution containing 1M LiClO4 and small amount of H2O) and TOIROF was also presented. The ECD showed a transmission modulation at 633 nm between -0.6 and -0.2. The excess of H2O in the nonaqueous electrolyte was found to lead to the deterioration of the WO3 films.View full abstractDownload PDF (249K) -
Kei Miyamoto, Yuzuru Takahashi, Suguru Inamura, Hiroki Miyamoto, Gun K ...1990 Volume 37 Issue 1 Pages 31-33
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThin Plates of BGO single crystals which have good opto-electric properties were grown by EFG method. By using a box-shaped crucible instead of a cylindrical crucible, the horizontal temperature gradient of the top of the die was decreased within 3°C. Consequently, a large thin plate of BGO single crystal with a good quality was stably grown. The size of the crystal was a width of 32 mm, a length of 40 mm and a thickness of 2 mm. The extinction ratio of the crystal was larger than 2000.View full abstractDownload PDF (1218K) -
Sachio Toyota, Mitsuhiro Takata1990 Volume 37 Issue 1 Pages 34-37
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDefect-free and homogenous PLZT ceramics were prepared by vacuum sintering and succeeding HIP. Maltilayer shutters and small size switching elements were made by using the PLZT. The maltilayer shutters have a polarized ratio of 0.989 at wavelength of 545 no. The switching speed which exceeds 10 nano-second was observed in the small size switching element.View full abstractDownload PDF (2450K) -
[in Japanese]1990 Volume 37 Issue 1 Pages 40
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (55K) -
Katsuyoshi Hotta, Toshimasa Suzuki, Haruo Hirose1990 Volume 37 Issue 1 Pages 41-45
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSWater (liquid or vapour) effects on high- Tc superconductors have been reported by several investigators. We argued in the preceding report these effects for the Bi-Pb-Sr-Ca-Cu-O system superconductor by magnetic and electrical characteristics in addition to SEM observations and X-ray diffraction. However such deterioration of superconductivity as Tc decrease was observed as has been expected, SEM images suggested possible improvement in the critical current Jc or increase in pinning sites by solving the materials existing around the crystals periphery into the water. This article reports the results of Jc measurements for the liquid water effect and the related magnetic behavior. The maximum magnetization is found to behave similarly to the critical current Jc with respect to water soaking time. That the surface of the sample is also found partly suffered from the electron beam current of the electron microscope may suggest a result of the water effect.View full abstractDownload PDF (2298K) -
Tamotsu Noda, Teruo Isuzu, Akio Nakamura, Yuu Shiohara, Shoji Tanada1990 Volume 37 Issue 1 Pages 46-49
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIt is necessary to understand phase equilibria in the Bi-system to effectively produce superconductors in this system. Experiments were performed using a quench method together with microscopic study as well as composition analyses by ICP and EPMA. Equilibrium phases at different temperatures were investigated and plotted on a quasi-binary temperature versus composition diagram between the nominal compositions Bi2 Sr2 Ca2 Cu3 Ox (2223, the high Tc phase) and Bi2 Sr2 Ca Cu2 Ox (2212, the low Tc phase). The liquidus temperature of the compound with the 2223 nominal composition found to be above 1100°C, and the primary solid phase formed to be Carich oxide. These results contradict those in previously reported phase diagrams, in which the temperature of the liquidus is about 1000°C. The liquidus lines along the composition axis as well as the primary phase coresponding to these lines Is also reported.View full abstractDownload PDF (170K) -
Hiroshi Nagai, Masahiro Kakuzen, Masaru Yokota, Kazuhiko Majima1990 Volume 37 Issue 1 Pages 50-53
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTwo peaks in the resistivity of the Bi2Sr2CaCu2Oy were detected at 300 and 650°C on heating process, but no peak was detected at 300°C on cooling process in spite of holding at 300°C for 100hr. In order to elucidate the cause of the peak at 300°C, the measurments of high temperature resistivity, Tc, thermogravimetry and X-ray diffraction were carried out for the Bi2Sr2CaCu2Oy quenched for various temperatures. Tc and normal-state resistivity as a function of a quenching temperature, Tq, had a steep minimum at Tq=300°C. The high temperature resistivity was also strongly dependent on Tq, but had a peak or a slope change at about 300°C on heating. X-ray diffraction showed that no change was found before and after quenching or high temperature resistivity measurement up to 400°C. The weight decrease was detected at 350°C during heating in air, but little change during cooling process. From these results, it may be considered that the peak in the resistivi-ty at 300°C is due to the decrease in the electrical hole concentration compensating the increase in the oxygen vacancy concentration. Further detailed research is in progress.View full abstractDownload PDF (203K) -
Jun Takada, Toshio Egi, Kiichi Oda, Hitoshi Kitaguchi, Akiyoshi Osaka, ...1990 Volume 37 Issue 1 Pages 54-59
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe influence of the calcining temperature on the formation of the high-Tc phase and the electrical conductivity has been studied for the sample with a nominal composition of Bi0.96Pb0.24Sr1.0Ca1.1Cu1.6Ox. The product in the sample calcined at 680°C was much different from that in the sample calcined at 800°C. Namely, Bi0.46Ca0.54-ySryOz(0.1<y<0.2), Bi10Ca7O22, Ca2PbO4, SrCO3 and CuO were formed at 680°C, while the low-Tc phase and Ca2PbO4 were mainly formed at 800°C. At 850°C, the fraction of the high-Tc phase increased more quickly in the sample calcined at 680°C than in the sample calcined at 800°C, and mostly monophasic high-Tc phase was obtained by the sintering at 850°C for 24h after the calcination at 680°C, however, that sample showed lower Tc(zero)=87K than the sample calcined at 800°C.View full abstractDownload PDF (1245K) -
Satoru Ohno, Hideo Okuyama, Kazuhiro Honma, Masaya Ozawa1990 Volume 37 Issue 1 Pages 60-63
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe superconductive ceramics of Bi-Sr-Ca-Cu-O system, (4336) has been synthesized using the mixed powder of carbon free materials [Bi2O3, Sr(OH)28H2O, Ca(OH)2 and Cu2O]. The properties of synthesized ceramics were examined by X-ray diffractometry, scanning electron microscopy, electron probe microanalysis and susceptibility measurement. The most favorable temperature range for the high Tc phase formation was between 870°C and 880°C, regardless of the mixed powder was calcined or not. It was found that the large crystal of Ca-Sr-Cu-O phase crystallizes in a matrix at initial sintering stage and the superconductivity of synthesized ceramics increases as the crystal dissolves into the matrix.View full abstractDownload PDF (1694K) -
Hiroharu Nakashima, Toshihide Ohnishi, Tetsuya Hasegawa, Kohji Kishio, ...1990 Volume 37 Issue 1 Pages 64-68
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSChemical composition, oxygen nonstoichiometry and its effect on superconductivity of a single CuO2-layer compound, Bi-Sr-Cu-O were investigated. The critical temperature, Tc, was strongly dependent on cation and oxygen compositions and the optimum cation composition found in this study was around Bi2Sr1.875Cu1. 126Ov. Its oxygen content, y, was examined through chemical titration analysis after quenching the specimens from various temperatures. It was found that the formal valence of Cu was in a range from 2.05 to 2.15 and maximum Tc appeared to exist at around 2.1.View full abstractDownload PDF (242K) -
Hiroshi Nagai, Kenn Ohobayashi, Masaru Yokota, Kazuhiko Majima1990 Volume 37 Issue 1 Pages 69-72
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe effect of partial substitution of Ba for Sr or Ca in the BiSrCaCu2Oy on the formation of the high-Tc phase was studied. A series of samples BiSr1-xBax CaCu2 Oy and BiSrCa1-x Bax Cu2 Oy, (x=0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.5, 1.0) was prepared by the conventional ceramic method. The differential thermoanalysis and microstructural observation revealed that the substitution of Ba for Sr lowered the melting point and partial melting temperature and widened the temperature range of the partial melting with increasing Ba substitution(x≤0.1) for Sr. Tc measurements and X-ray diffraction analyses showed that the fraction of the high-Tc phase was at maximum when the BiSr1-x Bax CaCu2 Oy, (x=0.1) was sintered in the partial melting region. The partial substitution of Ba for Ca also lowered the melting point and partial melting temperature, but showed little effect on the formation of the high-Tc phase.View full abstractDownload PDF (199K) -
Toshiyuki Ido, Hiroshi Terada, Saburo Muto1990 Volume 37 Issue 1 Pages 73-76
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe single crystals of the superconductor in Bi system were prepared by gradual cooling method using the compound calcined Bi2O3, SrCO3, CaCO3, and CuO powders. The growth runs were started at 960°C and a cooling rate of 5-16°C/h was employed. Single crystals 5×3×0.5mm3 were obtained. They showed that the zero-resistivity temperature was 78K, indicating the low temperature phase. It was also verified by XRD. The annealing at 840°C in 30h did not change the characteristics of the resistivity and XRD. The starting material with the differnt composition from the stoichiometry showed lower zero-resistivity temper-ature as a polycrystal.View full abstractDownload PDF (3000K) -
Toshihiko Nishida, Takashi Ohtsuka, Susumu Shimano, Takeshi Shiono, To ...1990 Volume 37 Issue 1 Pages 77-82
Published: January 25, 1990
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSBi2Sr2CaCu2Ox ceramic powder prepared by solied-state reaction was encupsulated in SUS304 stainless steel mold with dimentions of 20φ(O.D.) - 10φ(I.D.) × 30hmm. The mold were heated at 840°C for 10 minutes and were press-forged rapidly under various uniaxial compressive loads to avoid excessive heat loss. Density of the processed ceramics was estimated from the results of Vickers hardness(Hv) measurment. The Orientation degree(f) of the superconducting (00l) plane of the crystal grains was determined by an X-ray diffraction analysis of the polished surface of the ceramics. The values of Hv and f increased with an increase in the deformation ratio of the mold during the processing.View full abstractDownload PDF (2173K) -
Jun Takada, Hiroaki Asano, Hitoshi Kitaguchi, Kiichi Oda, Akiyoshi Osa ...1990 Volume 37 Issue 1 Pages 83-88
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIt is well known that HIP treatment provides highly densified ceramics. The influences of HIP treatment on the densification of the Bi-Pb high-Tc ceramics and the electrical conductivity have been studied on the sample with a nominal composition of Bi0.96Pb0.24Sr1.0Ca1.1Cu1.6Ox. It was found that the density of the sample was attained over 90% of the theoretical density of the Bi-Pb high-Tc phase by the HIP treatment at 850°C for 2h. While the electrical resistance of the sample without HIP treatment decreased in linear with decreasing temperature from 280K to 120K and dropped to zero near 100K within the experimental limit, that of the HIP treated sample increased semiconductively between the temperature range from 280K to 110K, and below 110K gradually dropped to zero at 60-70K. However, the degradation of the HIP treated sample in the electrical conductivity was recovered by the heat treatment at 850°C for 48h in air. This behavior in the electrical conductivity seems to be associated with the precipitation of Ca2PbO4 in the grain boundary and the deficient of oxygen in the high-Tc phase.View full abstractDownload PDF (2242K) -
Yoshiyuki Nishikawa, Makoto Hiraoka, Keisuke Yamamoto, Takeshi Shintan ...1990 Volume 37 Issue 1 Pages 89-93
Published: January 25, 1990
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSBy using plasticized superconducting raw compounds, we extruded string-shaped and tape-shaped wires. Adopted Bismuth-lead-strontium-calcium-copper oxides (Bi-Pb-Sr-Ca-Cu-O) have been produced by solid-state reactions. They were calcined at 850°C for 50 hours, ground, re-calcined and re-ground. The composition of Superconducting pawders were Bi0.7Pb0.3SrCaCu1.5Oy.
Plasticized superconducting raw compounds consist of the binders(PVB), the plasticizers(DOP), the dispersants and ceramic powders. Raw compounds were ex-truded to the 1.5mm∅ strings and the 0.5×3.0 or 5.0(thickness×width, mm) tapes.
These strings and tapes were sintered, and the superconducting properties(Tc, Jc, SEM, XRD) were measured.
The sintering conditions were at 830-850°C, for 50-200 hours. Tc's were not so differed by sintering temperatures and times.
The sintered tape-shaped specimens seemed to have the c-axis orientations with the observation of XRD-patterns and SEM-fractured surface.
Jc's of tape-shaped wires were superior than string-shaped wires. These values were 60-85, 163-174A/cm2 at 77K OT respectively.The Jc of the wire added about 0.3 wt.mole silver to 1.0 wt.mole BSCCO was 268A/cm2.View full abstractDownload PDF (1219K) -
Seiichro Kashu, Yasuyuki Matsuzaki, Makoto Kaito, Makoto Toyokawa, Kei ...1990 Volume 37 Issue 1 Pages 94-98
Published: January 25, 1990
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSSuperconducting thick film of BPSCCO is formed on MgO substrate by gas deposition using fine powder of Oi-Pb-Sr-Ca-Cu-O(BPSCCO) having diameter less than 1μm. The pattern of the deposited film is linear, and the thickness of it can be controlled in the range of 5-200μm.
After heat treatment at 770°C for 10hr in air atmosphere, Tc(end) showed 105K and critical current density of 225A/cm2 are obtained at 77K in zero magnetic field.
The structure of the surface of thick film by X-ray diffraction pattern, and composition ratio of Ui and Pb in film, were reported.
Tape like BPSCCO thick film with width of 10mm was formed on substrate using similar method. Tape like thick film is expected to utilize as material of superconducting tape.View full abstractDownload PDF (2573K) -
Satoshi Nagai, Norifumi Fujimura, Taichiro Ito1990 Volume 37 Issue 1 Pages 99-102
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe behavior of excess atoms and the formation of the high-Tc phase were investigated on thin films crystallized from the amorphous Bi-Sr-Ca-Cu-O prepared by a rf magnetron sputtering. In the films which have more Ca and Cu than the stoichiometric 80K phase composition, formation of the 80K phase may cause the segregation of excess Ca and Cu atoms of grain boundaries by annealing at the special temperature range. Segregation and the vaporization of them have unfavorable influence on the surface structure and the electrical property. And by annealing at lower temperature, excess atoms do not segregate in spite of formation of the 80K phase. But, in the films which once formed the 80K phase, the 110K phase could not be obtained by post-annealing.View full abstractDownload PDF (3850K) -
Hiroshi Maiwa, Kazunori Komori, Masahiro Kato, Noboru Ichinose1990 Volume 37 Issue 1 Pages 103-107
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe phase diagram of (BiO)2Sr2Can-1CunO2n+2 of the line (1≤n≤8) could be determined. Based on the phase diagram, we were able to grow single crystals by the self flux method. The features of the crystals grown using such method were in good agreement with the phase diagram. The largest Bi2Sr2CaCu2Ox single crystal could be grown from the compound with nominal composition Bi2Sr2Ca2Cu3O10.View full abstractDownload PDF (2693K) -
Jun Takada, Fumine Shitani, Hitoshi Kitaguchi, Kiichi Oda, Akiyoshi Os ...1990 Volume 37 Issue 1 Pages 108-113
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe formation of the high-Tc phase and the electrical property have been studied for the Pb-rich sample with a nominal composition of Bi:Pb:Sr:Ca:Cu=0.726:0.374:1.0:1.0:1.65 sintered at temperature range between 840 and 853°C. The sample calcined at 800°C for 12h consists of a large amount of Ca2PbO4 and CuO beside the low-Tc phase. The low-Tc phase increases rapidly in an early stage of sintering and then decreases through a maximum as sintering is extended. On the other hand, the high-Tc phase increases much gradually in comparison with that in the Pb-poor sample of Bi:Pb:Sr:Ca:Cu=0.96:0.24:1.0:1.1:1.6 reported previously. The samples sintered in the temperature range from 845 to 853-C show Tc of about 110K, independent of sintering temperature.View full abstractDownload PDF (337K) -
Takafumi Aomine, Terukazu Nishizaki, Takahiro Yamamoto1990 Volume 37 Issue 1 Pages 114-117
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIt is known that sintered bulk samples of high Tc superconducting oxides have low critical current density and show hysteresis of critical currents in low magnetic fields. These phenomena are attributed to weak links at a grain boundary. In this work we report on the hysteresis of sintered bulk samples of high Tc superconducting oxides and of superconducting, relatively long bridges which have a constricted part made artificially. The former hysteresis is found to be very similar to the latter one. We consider that the hysteresis of sintered bulk samples of high Tc superconducting oxides occurs for the existence of superconducting, relatively long bridges and trapped flux in them.View full abstractDownload PDF (258K) -
Rikuo Ogawa, Kazuyuki Shibutani1990 Volume 37 Issue 1 Pages 118-121
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe effect of high pressure oxygen loading on the superconducting properties of La and Y type high-Tc superconductors have been studied b using O2-HIP (Oxy en Hot Isostatic Pressing). Superconductivity observed in 02-HIPed La×CuO4 and La2-×Ba×CuO4 was systematically investigated. Increase in Tc and Meissner signals by decrease in oxygen deficiency was observed and strong cooling rate dependency was found in superconducting La×CuO4. In YBCO system, tetragonal structure with high oxygen concentration was stabilized by O2-HIP. O2-HIP conditions to synthesis 1-2-4-8 phase were investigated in Y and Ho systems.View full abstractDownload PDF (257K) -
Wei Zhang, Kozo Osamura1990 Volume 37 Issue 1 Pages 122-126
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn the present study, the Ba-Cu-O and Y-Cu-O systems have been investigated. In the Ba-Cu-O system, a structure change of Ba2CuO3.3 phase from orthorhombic to tetragonal crystal symmetry was observed to occur at 1083K. The tetragonal phase exists in the higher temperature with the form of Ba2CuO3.1, the lattice constant was a=b=0.3991 and c=1.2968nm, the space group was 14/mmm. The isobaric section of BaO-CuOx under 0.21 atm. oxygen was determined. In the Y-Cu-O system, the isobaric sections and the phase diagrams of CuO0.5-CuO-YO1.5 were determined in various oxygen partial pressure. The existence of three invariant reactions in the Y-Cu-O system was confirmed.View full abstractDownload PDF (1254K) -
Masaru Yokota, Koichi Kanbara, Jun Imazu, Hiroshi Nagai, Kazuhiko Maji ...1990 Volume 37 Issue 1 Pages 127-130
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSInfluences of repressing and resintering on grain orientation of superconductive YBa2Cu3Oy ceramics were investigated.. Especially, infuluence of lubricants addition such as Ag, AgO or Ag2O on grain orientation and densification were studied by means of X-ray diffraction analysis and SEM observations; (1) First treat of repressing by static oil press and conventional resintering affected the densification, especially, Ag2O addition was favorable. On the other hand, more than 2 times of treats decreased the densities of specimens. (2) Dynamical working (swaging) affected both the densification and the grain orientation. (3) Critical current density(Jc) of swaged sample was about 25 times larger than that of as sintered sample.View full abstractDownload PDF (1783K) -
Makio Naito, Masahiro Yoshikawa, Tsutomu Yotsuya1990 Volume 37 Issue 1 Pages 131-133
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSOur new apparatus, called 'Mechanofusion System', which was developed by modifying a dry attrition type mill, can grind different kinds of powder materials down to submicron level, disperse them uniformly, and change them into composite particles.
In this paper, this apparatus was applied to prepare the raw powdery materials of Y-Ba-Cu-O superconductors. Although these raw materials were treated in single calcining and grinding process, the obtained superconductors showed the critical temperature of 90K class and the diffraction pattern of orthorhombic crystal structure of Y-Ba-Cu-O. On the other hand, when a dry vibration ball mill was substituted for this apparatus, a calcining and grinding process had to be repeated several times to obtain the product of the same quality.
It was found from the above results that this method was an effective one to prepare the raw powdery materials of ceramic superconductors.View full abstractDownload PDF (1199K) -
Hirohiko Murakami, Junya Nishino, Seiji Yaegashi, Koji Yamaguchi, Yuh ...1990 Volume 37 Issue 1 Pages 134-136
Published: January 25, 1990
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSWe have succeeded in producing of yttrium-barium-cuprate powders using metal alkoxides at below 650°C by sol-gel process. In this work, the basic experiments were focussed on the selection of metal alkoxides as starting materials and suitable solvents to prepare chemical homogeneous solution. A highly concentrated mixed alkoxides solution was prepared using Y(n-OC4H9)3, Ba(OC2H4)2, and Cu(N03)2 as starting materials and that the formation of superconducting 123 powders fired only at 650°C.
The powders were characterized by X-ray diffraction, TEM, and magnetic susceptibility measurements. X-ray diffraction patterns of the powders showed a presence of 123 single phase. TEM observation of this powder revealed small spherical partices with an average agglomerate size to be less than 0.05μm.View full abstractDownload PDF (1738K) -
Mamoru Ishii, Masasuke Takata, Kensuke Nakajima, Tsutomu Yamashita, Sh ...1990 Volume 37 Issue 1 Pages 137-140
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe flux penetration phenomenon and the flux profile have been studied by the measurement of the magnetic shielding properties of the Y-Ba-Cu-O cylindrical superconductor. The magnetic shielding properties were measured at 77.3K with the cryogenic hall probe, which was moved from the center to the perimeter of the cylindrical specimen. The flux penetrated from the perimeter towards the center of the cylindrical specimen and the external magnetic flux density, at which the flux started to penetrate, was approximately 7 gauss. This low value might be attributed to the flux penetration in the grain boundaries. Then, the flux profile inside the cylindrical specimen deviated from the critical state model with the increase of the external magnetic flux density.View full abstractDownload PDF (183K) -
Tsunekazu Iwata, Akihiko Yamaji, Youichi Enomoto1990 Volume 37 Issue 1 Pages 141-144
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSWe examined the structures of (110) preferred oriented YBa2Cu3Oy thin films by X-ray diffractometry with a 4-axis goniometer. It is noted that some films, in which the RHEED method had detected only the (110) domain, had (103) domains. The results indicate that the films have different structures between their surface and inside. So to characterize the precise structure of the films, this X-ray diffraction method is very useful.View full abstractDownload PDF (1028K) -
Masao Kimura, Akihiko Hayashi, Mitsuru Morita, Munetsugu Matsuo, Kiyos ...1990 Volume 37 Issue 1 Pages 145-148
Published: January 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe bulk material of YBa2Cu3O7-x prepared by the Quench and Melt Growth (QMG) process was characterized from crystallographic points of view. It was shown that the QMG-processed material was a composite of YBa2Cu3O7-x (123) matrix and Y2BaCuOy (211) dispersoids. Because the material was highly oriented, analysis of the crystal structure was carried out by means of a modified method of texture analysis. It was found that the matrix consisted of only a few twinned crystallites of the order of 10-2m which were related to each other with boundaries of little difference in angle. The material was concluded to be a large grain composed of 123 crystallites containing a fine dispersion of 211 phase.View full abstractDownload PDF (1994K) -
Hiromasa Mazaki, Hiroshi Yasuoka, Shigeru Katsuyama, Koji Kosuge, Yuta ...1990 Volume 37 Issue 1 Pages 149-152
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMeasurements of complex susceptibility of YBa2(Cu1-xFex)3Oy (0 ?? x ?? 0.20) were made in the temperature region of 100-5 K.
Two different methods were adopted to prepare the samples. Group I was prepared by slow cooling from 850°C in flowing oxygen gas. Group II was prepared by heating in flowing nitrogen gas at 800°C for 20 h, followed by slow cooling to room temperature in the same atmosphere and then by annealing in flowing oxygen gas below 400°C for more than 20 h. Comparisons of the results suggest that the samples in group II contain the 90-K phase for all the values of x used. From the present results and our previous works, we think that the clustering of substituted Fe ions takes place in the Cu-1 planes of these samples.View full abstractDownload PDF (215K) -
Kazunuki Yamamoto, Kazuto Hirata, Kenji Iijima, Katsuhiko Hayashi, Hir ...1990 Volume 37 Issue 1 Pages 153-156
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSHigher-harmonic ac susceptibility was investigated for single-crystal YBa2Cu3O7-x thin films, when a magnetic field was applied perpendicular to the film plane. Real and imaginary part of the harmonic susceptibility were successfully measured independently each other. Odd terms had finite values and varied complicatedly in the temperature region when the imaginary part of fundamental susceptibility formed a single peak. Second harmonic also had a finite value, however, its value was extremely small. These results suggest the existence of some mechanism to obstruct the vortex motion in the specimen.View full abstractDownload PDF (202K) -
Takahito Terashima, Yoshichika Bando, Kenji Iijima, Kazunuki Yamamoto, ...1990 Volume 37 Issue 1 Pages 157-161
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSSuperconducting Nd-Ce-Cu-O thin films were epitaxially grown on SrTiO3(100) by activated reactive evaporation. As grown films showed the metallic temperature dependence of the resistivity and superconducting transition at 12.5 K (R=0). The remarkable parallel shift of the onset temperature of the resistive transition in the magnetic field was observed. Ginzburg-Landau coherence length along the c axis and in the basal plane are 7 Å and 96 Å, respectively.View full abstractDownload PDF (913K) -
Nobutaka Kojima, Masaki Kato, Kazuyoshi Yoshimura, Koji Kosuge, Yutaka ...1990 Volume 37 Issue 1 Pages 162-165
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe La4BaCu5O ?? with the orthorhombic structure has been prepared for the first time by the following heat treatments : firing in flowing N2 gas at 780°C or quenching into liquid N2 from 1000°C in air. The oxygen content of this phase (the high-temperature phase) is y=12 in La4BaCu5O ??, and that of the well-known tetragonal phase (the low-temperature phase) is y=12.5. We have proposed the new structure model for the tetragonal phase in which the structure is built up by only CuO5 pyramids and also for the orthorohmbic phase built up by CuO4 squares and CuO5 pyramids (regularly arranged). This orthorohmbic phase has also metallic conductivity down to 4.2K.View full abstractDownload PDF (232K) -
on the Effects of Sr and Oxygen ContentsKazuyoshi Yoshimura, Youichi Nishizawa, Koji Kosuge, Yutaka Ueda1990 Volume 37 Issue 1 Pages 166-171
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe ac susceptibilities were measured on the powdered samples of La2-xSrxCuO ?? with various Sr and oxygen contents. Only the sample containing x-0.16 and y-4 showed the sharp superconducting transition at Tc=38K with a large volume fraction, f, of more than 80%. The others had rather broad transitions at lower temperatures with smaller f, while the onset temperature of the Meissner effect was close to 38K, suggesting that there existed a small amount of superconducting phases with Tc of 38K, and that the weak coupling in between by the Josephson effect took place at lower temperatures. These results may imply that only the compound with x-0.16 and y-4 is intrinsic in the superconductivity of this system.View full abstractDownload PDF (321K) -
E Gang, Shinichi Kikkawa, Fumikazu Kanamaru, Yoshinari Miyamoto1990 Volume 37 Issue 1 Pages 172-175
Published: January 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSYBa2Cu3O ?? with y>7 and y<6.5 were prepared under high pressure conditions of 3GPa, 830°C, 8hrs. BaO2 and BaCuO2 were respectively used as barium source. Both phases of YBa2Cu3O ?? were tetragonal with a = 1/3c = 3.87A, c = 11.60Å and a = 3.86Å, c = 11.70Å respectively. They were semiconductors. YBa2Cu4O8 was obtained with BaY2F8 from a mixture of Y2O3 : YF3 : BaO2 : CuO = 0.9 : 0.2 : 4 : 6 under conditions of 3GPa, 830°C, 8hrs. The product showed Tc around 90 K.View full abstractDownload PDF (205K)
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