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Volume 35, Issue 5
Displaying 1-36 of 36 articles from this issue
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[in Japanese]1988 Volume 35 Issue 5 Pages 299-300
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESS -
Hajime Asano1988 Volume 35 Issue 5 Pages 301-304
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSSince the discovery of high-Tc superconductivity in the La-Ba-Cu-O system, many kinds of oxide-superconductors have been found out: the 40K-superconductor La2-xAxCuO4 (A = Ca, Sr and Ba), the 90K-superconductor RBa2Cu3O7-y (R = Y and most of the lanthanide elements) and newly discovered Bi- and Ti-oxide systems. These compounds, together with BaPb1-xBixO3 of Tc = 12K, are based on the perovskite-related structure. The present paper reviews common structural features in these oxide-superconductors.View full abstractDownload PDF (2250K) -
Yoshichika Bando1988 Volume 35 Issue 5 Pages 305-312
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSBy means of the activated reactive evaporation, single crystal thin films of YBa2Cu3O7-x with their (001) and (110) planes parallel to the corresponding surfaces of SrTiO3 have been obtained successfully. The substrate temperature was kept at 500650°C and a subsequent in-situ oxidation treatment was performed below the growth temperature. An ac-resistive measurement for a (001) film 1000A thick gave a sharp superconducting transition with an end point of 90.2K and ΔTc(10-90%)=1.7K. The highest Jc of 4×106 A/cm2 at 77K was achieved for the thickness. From a complex susceptibility measurement we confirmed the Meissner effect as well as the structural uniformity of the films prepared. For the films grown on SrTiO3(110), the RHEED patterns have shown that the films have the (110) or (103) orientation depending on the substrate temperature.View full abstractDownload PDF (1048K) -
Hiroshi Komatsu, Shigeyuki Hayashi, Tetsuo Inoue1988 Volume 35 Issue 5 Pages 313-317
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe methods of single crystal growth of well-qualified high-Tc Superconductors [La2CuO4 type and ABa2Cu3O7-δ (A=Y, Eu, Er, Dy, Ho, Yb)] were described. The growth mechanism of these crystals was analysed to be a lateral growth type by surface microtopographic observation of as-grown surfaces. The crystals show many spiral layers with giant Burgers vector, whose origin was discussed in terms of the crystal habit.View full abstractDownload PDF (3627K) -
Shoichi Matsuda1988 Volume 35 Issue 5 Pages 318-320
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe transport Jc of YBa2Cu3Ox increased with sintering temperature and after a maximum of 1100 A/cm2 turned to decrease. Microcracks and second phases such as BaCuO2 and CuO along grain boundaries were observed. Magnetizatin measurement showed that single crystalline YBa2Cu3Ox made by a melt technique was almost free from weak links as differed from sintered samples. Clear specific heat jump at Tc was observed for YBa2Cu3Ox giving about (Δ Cp/Tc) of 52 mJ/mole·K2. Cu 2p core-level XPS spectra of YBa2Cu3Ox exibited a two peak structure. The higher (satellite) and lower (main) binding energy corresponded respectively to 2p3d9 and 2p3d10 L final-state configurations.View full abstractDownload PDF (357K) -
Osamu Kohno1988 Volume 35 Issue 5 Pages 321-324
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe wire processes of high Tc superconducting oxides are studying to realize its application in the field of electric power, however, the critical current density of oxide wire stays in the low range of 102 to 103 A/cm2. In this paper, the two latest results of our studies for fabricating the superconducting oxide to the wire will be presented.View full abstractDownload PDF (672K) -
Katsuzo Aihara, Michiya Okada, Akira Okayama, Toshimi Matsumoto, Shinp ...1988 Volume 35 Issue 5 Pages 325-328
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSA tape-shaped wire with YBa2Cu3O7 core and Ag sheath was fabricated by a drawing-rolling method. The critical current density Jc apparentry depended on the thickness of the tape and increased markedly with decreasing tape thickness. The maximum Jc of 3330A/cm2 at 77K in a zero magnetic field was achieved in a tape with 0.06mm thickness. The presence of a 20mT magnetic field reduced the Jc value by 1/100.View full abstractDownload PDF (350K) -
Yasunori Ikeda, Yasushi Oue, Kazuhisa Inaba, Mikio Takano, Yoshichika ...1988 Volume 35 Issue 5 Pages 329-332
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe Y2O3-BaO-SrO-CuO system was found to have the superconducting phase Y(Ba1-xSrx)2Cu3Oy where x ranges up to about 1.5. Another new ternary compound Sr3Cu5Oδ was identified. This phase has orthorhombic structure with lattice constants a=3.950Å, b=13.376Å, and c=11.468Å, and solid solution region enclosing Sr3Cu5Oδ, YSr2Cu5Oy, and BaSr2Cu5Oz.View full abstractDownload PDF (317K) -
Tatsuya Yamamoto, Takayuki Furusawa, Hideaki Seto, Kyonho Park, Kazuyu ...1988 Volume 35 Issue 5 Pages 333-338
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSSubmicron-size superconducting powders Ba2YCu3O7-δ(BYCO) having good homogeneity and reactivity were synthesized by an ethanol-aided coprecipitation method by oxalic acid. The obtained ceramics sintered at 1020°C had densities up to 98% of theoretical and exaggerated grain growth was observed at 1000°C and above. A prolonged annealing in flowing oxygen, for as long as 3 weeks, was needed to attain the zero resistivity critical temperature Tc zero=92K for the dense BYCO. A sharp superconducting transition, Tc=0.5K, was then obtained as defined by 10%-90% resistive transition.View full abstractDownload PDF (4582K) -
Sumio Sakka, Hiromitsu Kozuka, Tetsu Umeda, Takashi Monde, Jisun Jin1988 Volume 35 Issue 5 Pages 339-343
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSSuperconducting YBa2Cu3O7-x fibers and coating films have been prepared using solgel method. Homogeneous viscous sol was prepared by concentrating an aqueous solution of metal acetates. Gel fibers of 5μm - 2 mm in diameter and of more than 50 cm in length could be drawn from the sol. Heat-treated fibers had a hollow structure and were fragile, but showed superconductivity of Tc(end) at 73 K. For preparation of YBa2Cu3O7-x coating films, metal alkoxide solution was prepared using triethanolamine to dissolve copper alkoxide. Repeated application of the solution on a zirconia substrate and heat treatment in O2 resulted in the formation of a superconducting coating film of 1.5 μm in thickness having Tc(end) at 56 K. Factors affecting the properties of the fibers and coating films have been discussed.View full abstractDownload PDF (3404K) -
Toshihiko Nishida, Takeshi Shiono, Hideaki Fujioka, Tomozo Nishikawa1988 Volume 35 Issue 5 Pages 344-348
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSOrthorombic YBa2Cu3Oy ceramic powder prepared by solid-state reaction was cupsulated in SUS 304 stainless mold with the dimensions of 22φ-10φ×30h mm. The molds were preheated at a temperature of 950°C for 5 minutes, and then press-forged in a few seconds under uniaxial compressive load. Deformation ratio of the mold was about 30% of the original height and the maximum loads were about 5 ton/cm2. X-ray diffractometry on the polished surface of the press-forged ceramics showed the superconducting (00Q) planes had the preferential orientation perpendicular to the pressing axis.View full abstractDownload PDF (4626K) -
Yasuo Takeda, Ryoji Kanno, Kazunari Ina, Osamu Yamamoto, Mikio Takano, ...1988 Volume 35 Issue 5 Pages 349-352
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe sintered YBaSrCu3Oy was treated at 300-600°C under high oxygen pressure (PO2=20600atm). The samples showed the decrease of orthorhombic distortion with decreasing the annealing temperature. Below 350°C under 100atm, orthorhombic YBaSrCu3Oy transformed to tetragonal phase with the increase of oxygen content ( y>7.0). The superconductive transition temperature was almost comparable to tho orthorhombic YBaSrCu3Oy.View full abstractDownload PDF (493K) -
Kunihiro Nagata, Takahiko Iwai, Tatsuya Kiyota1988 Volume 35 Issue 5 Pages 353-357
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSWe have studied that the characteristics of YBa2Cu3Ox superconducting ceramics with hot-pressed in air and oxygen atmosphere was affected by the oxygen diffusion. In the hot-pressed samples in air, since absorbed about 40% oxygen compare that a ordinary sintered methods, it's structure indicated either the tetragonal or the orthorhombic close to tetragonal, besides superconducting did not show until near 77K in spite densification. While the hot-pressed samples in 2-3atm. of oxygen with adding 1-10wt% Ag2O not only indicated the orthorhombic phase but also showed superconducting at 91K regardless of densification, since it was to promote a high oxygen content within material during a sintering process. Therefore we believed that a superconducting and crystal structure of sample was affected by sensitive changes in oxygen content.View full abstractDownload PDF (753K) -
Kazuhiko Majima, Masaru Yokota, Hiroshi Nagai, Ken Obayashi, Toshikatu ...1988 Volume 35 Issue 5 Pages 358-361
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSY Ba 2Cu3Oy powders obtained by pulverizing the mixed powder aggregate fired at 1173K for 86.4ks were cold pressed at 98MPa and sintered at various temperatures for 86.4-1036.8ks, and the relation between the sintering behavior and superconducting properties was investigated.
The abrupt increment of sintered density ratio was observed by the sintering at 1198K after gradual increment with rising sintering temperature up to 1173K, and it remained constant in the higher sintering temperature range than 1198K. Though the sintered density ratio was about 72% even after sintering at 1173K for 1036.8ks, it exceeds 90% in the case of sintering at 1223K for 1036.8ks. The marked degradation of superconducting properties was recognized in the specimen sintered at 1223K for 759.6ks, where the lamella structure along the grain boundary due to the liquid phase formed during sintering was observed.View full abstractDownload PDF (926K) -
Kunihiro Nagata, Takahiko Iwai, Kiyoshi Okazaki1988 Volume 35 Issue 5 Pages 362-367
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe effects of pore structure on the characteristics of YBa2Cu3Ox superconducting ceramics was investigated. The density of YBa2Cu3Ox ceramics, which is related to pore size and surfaces, was controlled by calcining, milling and sintering condition. The density of samples ranging from 4.80 to 6.17g/cm3 was made by calcining temperature at 900-940°C, dry or wet mill and sintering temperature at 900-1000°C. The resistivity of samples in 300K decreased with increasing density up to 6.00g/cm3, increasing beyond that density and Tc were shift to a low temperature above 6. 00g/cm3. Inversely the critical current density increased with density, but it decreased in case of a magnified densification.View full abstractDownload PDF (695K) -
Hiroshi Nagai, Masaru Yokota, Kazuhiko Majima, Ken Ohobayashi1988 Volume 35 Issue 5 Pages 368-372
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSEffect of Fe substitution for Cu(up to 3at%) on the high temperature phase equilibria of YBa2 Cu3 Oy was investigated under various oxygen partial pressures by electrical conductivity, thermoelectric power measurements and X-ray diffraction. The YBa2 (Cu1-x Fex )3 Oy (x=0-0.03) had orthorhombic structure at room temperature. The electrical conductivity of YBa2 (Cu1-x Fex )3 Oy (x=0-0.03) increased abruptly at about 450°C and the temperature dependence of the resistivity showed a slope change at the temperature which corresponds to the orthorhombic-tetragonal transition. Arrhenius plots of the electrical conductivities of YBa2 (Cu1-x Fex )3 Oy measured under various Po2 consisted of five straight lines. The temperatures at which the straight lines intersected were confirmed to correspond to the phase transition temperatures, which markedly decreased with increasing Fe content(x). The thermoelectric power of YBa2 (Cu1-x Fex )3 Oy (x=0-0.03) is negative across the entire temperature range and Po2 range investigated, which indicates that YBa2 - (Cu1-x Fex )3 Oy (x=0-0.03) is of n-type. The temperature dependence of the thermoelectric power was very similar to that of the electrical resistivity.View full abstractDownload PDF (649K) -
Motohide Matsuda, Masasuke Takata, Tsutomu Yamashita, Shoichi Okamoto, ...1988 Volume 35 Issue 5 Pages 373-378
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe influences of the sintering temperatures in fabricating GdBa2Cu3O7-x ceramics on the critical current densities were investigated. The critical current density measured by the resistive method (Jc, res.) showed a maximum value for the sample sintered at 930°C, while that estimated from the magnetization loop (Jc, mag.) increased monotonically with increase in sintering temperature. The relationship between the decrease in Jc, res. and the second phase at grain boundary was discussed.View full abstractDownload PDF (2116K) -
Tsukio Ohtani, Tatsumi Uemura, Kazuo Ohkuma, Yasuhiro Oh-hashi, Hiroyu ...1988 Volume 35 Issue 5 Pages 379-381
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSYBa2(Cu1-xFex)3O7-y (x≥0.03) shows a tetragonal X-ray pattern different from that of well-recognized high-temperature tetragonal phase. Phase transition was observed at around 600°C for all samples (0≤x≤0.05) in magnetic susceptibility, electrical resistivity and thermoelectric power measurements. Seebeck coefficients of the pure YBCO were negative below about 500°C indicating complex conduction mechanism in the compound.View full abstractDownload PDF (341K) -
Masaru Yokota, Hiroshi Nagai, Kazuhiko Majima, Jiro Kondo, Ken Obayash ...1988 Volume 35 Issue 5 Pages 382-385
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSEffects of La addition substituting for Y in YBa2Cu3Oy on the supercoductivity were investigated. Powder mixtures of Y2O3, BaCO3, La2(CO3)3 and CuO were prepared by mechanical method, cold pressed at the pressure of 98 MPa, sintered at 1253K for 86.4 ks followed by 523K for 86.4ks and then furnace cooled in an oxygen atmosphere.
For estimating the superconductivity, electrical resistivity versus temperature was measured. X-ray diffraction analysis was performed to obtain diffraction patterns and determine lattice constants by using graphite monocromatized CuKα radiation and diffractometer.
Substitution of La for Y in YBa2Cu3Oy did not influence on Tc up to approximately 0.1mol La of Y in YBa2Cu3Oy. However, ΔTc was minimal at approximately 0.1mol La of Y, that is, superconductivity was stabilized by the substitution of La for Y. Over this, Tc inclined to lower with increasing La content. These experimental results may be related to the fact that sintered density of Y0.9La0.1Ba2Cu3Oy became larger than that of YBa2Cu3Oy at the same sintering conditions.
Tcoffset was achieved at 84 K for La0.64Ba2Cu3Oy sample; this is the highest Tc obtained among the LaBaCuO ceramics reported so far.
Lattice parameters of orthorhombic Y1-xLaxBa2Cu3Oy increased monotonously with the increase of La content up to 1 mol La of Y. Orthorhombic single phase was kept to exist up to approximately 0.2 mol of La for Y. Over this, mixture of orthorhombic phase and other phases were confirmed to be coexistent in the specimens.View full abstractDownload PDF (3627K) -
Takashi Hase, Hiroshi Kajikawa, Kouzou Nishimura, Masahiko Okuda, Yosh ...1988 Volume 35 Issue 5 Pages 386-391
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe composition of Y-Ba-Cu-O thin films deposited by RF diode sputtering was examined by EPMA (Electron Probe Micro Analysis). The composition of Y-Ba-Cu-O thin films with a target made by the solid state reaction method changed with sputtering time even if the films were deposited under identical conditions. In contrast, the composition of films with a target made by the co-precipitation method were unaffected by sputtering time when they were deposited under identical conditions. Good control of the composition of Y-Ba-Cu-O thin films was achieved by optimizing both the RF input power density and the partial pressure of oxygen.View full abstractDownload PDF (998K) -
Takeshi Kobayashi, Masayoshi Tonouchi, Yuuji Yoshizako, Masahiro Iyori ...1988 Volume 35 Issue 5 Pages 392-396
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSFirst attemt has been done in growing epitaxially the heterostructure YBaCuO/ LnBaCuO (Ln=Er, Nd) films. As an extended demonstration of the heterostructure, the superlattice structure was grown. The trilayered perovskite structure, however, was missing in the film (thinner than a few nm) grown on SrTiO3 substrates regardless of their crystal orientation. MgO was a promising material which can solve this problem.View full abstractDownload PDF (1312K) -
Jun Takada, Kazunuki Yamamoto, Kenji Iijima, Hiromasa Mazaki, Takahito ...1988 Volume 35 Issue 5 Pages 397-400
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSWe have fabricated quasiparticle tunnel junctions using superconducting single crystal thin film YBa2Cu3O7-x prepared by activated reactive evaporation method. From the tunnel measurement perpendicular to the Cu-O planes at 4.4K gap parameter Δ=11.5±1.5meV and 2Δ/kTc=3.2±0.4 were obtained.View full abstractDownload PDF (425K) -
Shuichi Iida, Toshiharu Mitsui, Kiyoshi Abe, Naomi Matsubara1988 Volume 35 Issue 5 Pages 401-404
Published: July 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL OPEN ACCESSSince the new frames in physics present a divergenceless mathematical framework for the interaction between the electron fields and the zero-point photon fields, they provide a powerful tool for the analysis of the mechanism of the superconductivity. The minimal coupling effective Hamiltonian predicts that the interaction of a single electron field with a normal-mode of the photon can raise its amplitude by a magnitude of more than 10-7, so that, by the participation of the superconductive electron fields of more than 107 in the number, and, under the action of the proposed possible Q enhancement of the mesoscopic in-crystal resonator, a good possibility is present that a unified complex of the electron fields and the zero-point photon fields is cooperatively created in the specimen. Since this mechanism is spin-independent and has no direct relation to the phonon modes, no isotope effect nor serious effect from the magnetic ions is expected. Different from metals, since the oxides have the ionic lattice which is more rigid and more difficult to be excited by the photon fields, the coupling between the resultant electron-photon field complex and the thermal modes of the phonon fields of the lattice should be much smaller.View full abstractDownload PDF (895K) -
Yasunori Ikeda, Yasushi Oue, Kazuhisa Inaba, Yoshichika Bando, Mikio T ...1988 Volume 35 Issue 5 Pages 405-408
Published: July 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL OPEN ACCESSWe have studied the subsolidus phase relation in the BiO1.5-SrO-CaO-CuO system in air. The compounds were identified by X-ray and electron diffractions. New compounds, Bi7Sr7Cu6Ox, Bi7Sr8Cu5Oy, Bi4Sr8Cu5Oz, Bi0.46CaO0.54-xSrxOy (0.1<x<0.2), Bi3Sr4Ca3Oσ and Bi0.25Sr0.75-xCax, Oy (0≤x<0.2) were found in the system.View full abstractDownload PDF (431K) -
Takayuki Uchida, Masahiro Itoh, Takahiro Takigawa, Keizo Gomi, Yujiro ...1988 Volume 35 Issue 5 Pages 409-412
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSOptimum composition was determined presisely on new oxide superconductor Bi-Sr-Cu-O system and substitution effects on Bi-Sr-Cu-O and Bi-Sr-Ca-Cu-O system were studied by electric and magnetic measurements. Maximum Tc (onset 10K) was observed at the composition ratio of Bi:Sr:Cu=1:1:1 (designated as BiSrCuOy) in the Bi2O3-SrCO3-CuO ternary system. Transition temperatures were increased with the substitution of light rare earth elements or Ca for Bi or Sr but were decreased with any other substitution. In the case of Bi-Sr-Ca-Cu-O system substitution with Pb, La, Nd, Yb or Lu for Bi or Sr are considered to be valuable for improvement of Tc and for obtaining single phase superconductor.View full abstractDownload PDF (526K) -
Hiromasa Mazaki, Yasunori Ikeda, Mikio Takano, Yoshichika Bando, Kiich ...1988 Volume 35 Issue 5 Pages 413-416
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe superconducting properties of Bi-Sr-Ca-Cu-O and Bi-Pb-Sr-Ca-Cu-O systems have been studied in terms of complex susceptibility. It has been revealed that partial substitution of Pb for Bi promotes the production of the high-Tc phase and the superconducting properties of the Bi-system are well improved.View full abstractDownload PDF (462K) -
Hiroki Miyamoto, Kei Miyamoto, Suguru Inamura, Yuzuru Takahashi1988 Volume 35 Issue 5 Pages 417-418
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSEffect of oxygen deficiency of BiSrCaCu2Ox on its superconductivity was studied. The resistance decrease of BiSrCaCu2Ox, fired at 870°C for 16 h, at about 110K increased from 80% to 86%, when the sample is annealed at 850°C in O2 atmosphere. By TG and DTA analysis, a lowering of melting temperature was observed when the sample is heated in Ar atmosphere.View full abstractDownload PDF (212K) -
Yoshio Oka, Naoichi Yamamoto, Yoichi Tomii, Hitoshi Kitaguchi, Kiichi ...1988 Volume 35 Issue 5 Pages 419-423
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe oxalate coprecipitation method was applied to the preparation of a new high-Tc superconductor BiSrCaCu2Ox and crystalline phases obtained by heat treatment were studied in connection with superconducting preperties. The pyrolysis of the coprecipitates was completed below 500°C and subsequent heat treatment above 800°C resulted in the formation of the layered structure characteristic to the superconducting phase. The particle shape was of thin flakes with the size of 10μm. The superconducting phase with Tc of 110K was formed by the heat treatment just below the melting point, which was enhanced in the melt - cooled sample.View full abstractDownload PDF (5592K) -
Kiichi Oda, Hitoshi Kitaguchi, Jun Takada, Akiyoshi Osaka, Yoshinari M ...1988 Volume 35 Issue 5 Pages 424-427
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSPartial substitution of Pb for Bi in the Bi-Sr-Ca-Cu-O system has been found to increase sharply the volume fraction of the high-Tc phase when both the starting materials, coprecipitated oxalate being used in the present study, and the heating process are appropriate. The sharp powder X-ray diffraction pattern of the high-Tc phase was obtained from well-grown particles, 1020μm wide and 0.5μm thick typically. The electrical resistance dropped to zero at 107K within the experimental limit of 10-6Ω. A large diamagnetic response in the ac susceptibility due to the Meissner effect was seen below 120K. The fraction of the high-Tc phase over the low-Tc phase was roughly estimated to be 9/1 in volume.View full abstractDownload PDF (2051K) -
Akihiko Yamaji, Makoto Hikita, Yoshikazu Hidaka1988 Volume 35 Issue 5 Pages 428-431
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSSingle crystals of Bi4(Sr, Ca)6Cu4Oz and Bi4(Sr, Ca)4Cu2Oz were grown from molten Bi2O3-SrCO3-CaCO3-CuO mixtures. These crystals have similar layered structures. The former crystal exibits superconductivity with Tc above 80K and shows Hc2 anisotropy of the ratio of 40-50 between a-b plane and c axis. The latter crystal shows no superconductivity down to 4.2K.View full abstractDownload PDF (3259K) -
Yuichi Shimakawa, Yoshimi Kubo, Takashi Manako, Yukinobu Nakabayashi, ...1988 Volume 35 Issue 5 Pages 432-436
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThree samples having general composition Tl2Ba2Can-1Cun04+2n (n=1, 2 and 3) were synthesized, and were examined their electrical properties and crystal structures. Rietveld refinement revealed that as n increased the lattice parameter, a, and interatomic distance Cu-O(2) became shorter, and the Tl-O and Ba-O layers showed a tendency to become flatter. Possible substitution of about 10% of the Ca-site with Tl ion in the 2212 and 2223 phases was also suggested.View full abstractDownload PDF (446K) -
Yutaka Ueda, Koji Kosuge1988 Volume 35 Issue 5 Pages 437-441
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSYBa2Cu3Oy with the perfectly ordered Cu1 planes was successfully prepared in the wide composition range of y by slowly cooling in O2 and N2 gases, and the superconductive properties were examined. By "perfect order", one means that the a-sites are empty and the b-sites are fractionally, randomly occupied by oxygen. From resistivity measurement under magnetic fields, the superconductive properties of oxygen deficient YBa2Cu3Oy seem to be composed of two components. The two components may be related to the electronic states of the Cu2 and Cu1 planes.View full abstractDownload PDF (606K) -
Hiroaki Toda, Yutaka Ueda, Koji Kosuge1988 Volume 35 Issue 5 Pages 442-445
Published: July 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL OPEN ACCESSThe SmxBa1-xCuOy system has been investigated by powder X-ray diffraction, electrical resistivity (R) and thermogravimetric analysis (TGA) measurements. This system forms a solid solution in the composition range 0.33≤x≤0.50. With increasing x, this system undergoes a phase transition from the orthorhombic to tetragonal structure around x≅0.41. The temperature dependence of R shows two step drops (Tc1, Tc2) toward zero resistivity on cooling, which behavior is very similar to the one observed in YBa2Cu3Oy. Tc2 gradually decreases through the orthorhombic to tetragona phase.View full abstractDownload PDF (474K) -
Tsutomu Yoshitake, Yosimi Kubo, Hitoshi Igarashi, Tetsuro Satoh1988 Volume 35 Issue 5 Pages 446-449
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThin films of Bi-Sr-Ca-Cu-O system were prepared on (100)MgO substrate by coevaporation of Bi2O3, Sr-Ca alloy and Cu metal. The films with relatively high Ca composition showed a superconducting transition with zero resistance Tc of 107K after annealed at 890°C for 5 hours. High Ca composition, high annealing temperature and long annealing duration were necessary to prepare the films with zero resistance Tc over 100K. These films showed large anisotropy of the upper critical field.View full abstractDownload PDF (484K) -
Yutaka Iwai, Takao Maeda, Mamoru Ishii, Masasuke Takata, Tsutomu Yamas ...1988 Volume 35 Issue 5 Pages 453-456
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSThe superconductive properties of the (1-x)YBa2Cu3O7-y - xTbBa2Cu3Oz system were studied. The structures are orthorhombic and lattice parameters are independent on the concentration of Tb for x<0.50. The transition from orthorhombic to tetragonal occurs for x>0.50. Critical temperatures are higher than 90K for x<0.50 and decrease for x>0.50, and superconductivity desappears at x=0.75.View full abstractDownload PDF (383K) -
[in Japanese]1988 Volume 35 Issue 5 Pages 457-464
Published: July 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL OPEN ACCESSDownload PDF (1125K)
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