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Volume 34, Issue 10
Displaying 1-31 of 31 articles from this issue
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[in Japanese]1987 Volume 34 Issue 10 Pages 529-530
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (110K) -
Akira Ono1987 Volume 34 Issue 10 Pages 531-534
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe compound Ba2YCu3O7-y with various 7-y was annealed in sealed gold and silica capules at 350-570°C and 0.1 MPa. Linear depression of the superconducting transition temperature(Tc) occurred with a decreasing 7-y, and Tc was zero at 7-y= 6.40 -6.45. Tetragonal phase with 6.4>7-y>6.34 was unstable below 570°C. Superstructure due to regular arrangement of oxygen vacancies was observed at 7-y=6.48. The specimen was reactive with moisture, and became a non-superconductor, although the structure remained unchanged. Coexistence of tetragonal and orthorhombic phases was observed in a specimen with 7-y=- 6.47.View full abstractDownload PDF (851K) -
Mikio Takano1987 Volume 34 Issue 10 Pages 535-536
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA group of researchers belonging to a few different universities has been formed to study Ba2YCu3O7-δ and related oxides.from various aspects and to develope new systems. Phase diagram of the Ba-Sr-Y-Cu-O system has been drawn and microstructure formed on cooling at various rates from the molten state, preparation of fine powder, complex susceptibility of powder and sinterd pellets, microscopic structure observed by TEN and Mossbauer spectroscopy of 57Fe impurity, surface chemical composition, and effects of the application of high oxygen pressure (-108Pa) have been studied for the Ba2YCu3O7-δ, and some related systems. For the developement of new systems, we are trying to prepare two dimensional lattices of MO2 (M: transition metal ions with S=1/2) sandwitched by or sandwitching acceptor layers containing highly charged transition metals.View full abstractDownload PDF (127K) -
Toshizo Fujita1987 Volume 34 Issue 10 Pages 537-544
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMeasurements of powder X-ray diffraction, superconducting transition temperature Tc and Mössbauer effect were performed from 4.2 K to 1000K for doped systems of La1.85Ba0.15(Cu1-xMx)O4-δ(LBCMO) and YBa2 (Cu1-xMx)O7-δ (YBCMO) with M=Zn, Ga and all 3-d metal elements. In fact, Fe, Co, Ni, Zn and Ga could be substituted homogeneously for Cu at least up to 10% . For M = Fe, Co and Ga, phase transitions from the orthorhombic to tetragonal structure were found with increasing x in YBCMO. Across the structural transition, however, Tc decreases gradually with x and no anomalies were found. This suggests that the superconductivity occurs essentially in the 2-dimensional phane for both LBCMO and YBCMO.View full abstractDownload PDF (274K) -
Koichi Kitazawa1987 Volume 34 Issue 10 Pages 545-549
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSElectronic structure of the high Tc oxide superconductors is discussed based mainly on the author's observations of the electrical, optical, thermal and magnetic properties. Tentatively, the observations seem to be most systematically understood in terms of the concept of the RVB (Resonating valence bond) structure.View full abstractDownload PDF (194K) -
Keiichi Ogawa1987 Volume 34 Issue 10 Pages 550-558
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIt is known that oxygen atoms along the chain in a YBa2Cu3O6+x compound play an important role in the superdonducting properties. We review the behavior of the oxygen atoms in terms of the order-disorder transformation and its effect on the electrical and structural properties.View full abstractDownload PDF (1186K) -
Ayako Tokiwa, Masae Kikuchi, Yasuhiko Syono, Osamu Nakatsu, Norio Koba ...1987 Volume 34 Issue 10 Pages 559-562
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSuperconductig compounds of pseudo-ternary (Y, La, Ba)3Cu3Oy system were synthesized and crystallographic parameters and superconducting properties were measured. Compounds of YBa2-xLaxCu3Oy series were found to be single phase up to x=1 and orthorhombic to tetragonal transition at room temperature took place with x=0.5. Tc decreased with increasing x and superconductivity disappeared for x>0.6. These results can be interpreted to be due to the decrease in average valence of copper Ions from 2.33 of YBa2Cu3O7 with Increasing x, which was caused by the substitution of divalent Ba ions by trivalent La Ions. On the other hand complete solid solution was formed for Y1-xLaxBa2Cu3Oy series, where Tc decreased gradually with Increasing x. Considerable Increase In Tc was found for the La substituted specimens by annealing around 400°C for 24hrs.View full abstractDownload PDF (157K) -
Takeshi KOBAYASHI, Sadamu KITA, Masayosi TONOUCHI1987 Volume 34 Issue 10 Pages 563-566
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHigh Tc superconductor films were sputter-grown in several crystalline forms, e.g. the polycrystal, polycrystal with c-axis preferential orientation, and (110) epitaxial crystal. The film had the critical temperature as high as 87 K. The micro-fabrication technique on the basis of the wet etching by the phosphoric acid and FELLIOX-115 was proposed. The thin line (2-4 μm wide) thus made exhibited no significant degradation in its superconductivity. The grain-boundary in the patterned polycrystalline film served as a good Josephson junction operative even at 81 K. The constricted Josephson junction array device was fabricated for the use as a sensitive image sensor. A possible application of this kind of material to the luminescence device is also demonstrated.View full abstractDownload PDF (170K) -
Akihiko Yamaji, Youichi Enomoto, Toshiaki Murakami, Minoru Suzuki1987 Volume 34 Issue 10 Pages 567-570
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThere have been many efforts to obtain high quality thin films of superconducting oxides for scientific research and electoronic application. In this report, short review of research activities on preparation of thin flms and properties of sputterd superconduct-ing Ba2VCu3O7- ?? are reported.
1)Thin films of Ba2YCu3O7- ?? were grown epitaxially on SrTiO3 single crystal substrates by the rf magnetron sputtering method.
2)Tc(zero reisitance temperature) was around 80k.
3)Anisotropy of resistivity was measured and the anisotropy factor of 34 at 100k was obtained.
4)The large critical current density of 1.8x106 A/cm2 at 77.3k was realized.View full abstractDownload PDF (2079K) -
Kazuaki Utsumi, Junji Tabuchi, Yoshimi Kubo, Yukinobu Nakabayashi, Ats ...1987 Volume 34 Issue 10 Pages 571-574
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTwelve compositions of high Tc superconducting ceramic materials, with the compositios Ba2YCu3O7-δ and Ba2LnCu3O7-δ (Ln=La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu) were synthesized and studied. The authors have focused their studies on the ortho-tetra phase transition in the lanthanide compounds as well as the yttrium compound. The orthorhombic-tetragonal Ba2YCu3O7-δphase boundary in the δ-T daiagram was determind by the detailed isobar thermogravimetric(TG) measurement under the oxygen parial pressures of 1 to 0.01 atm. The transition temperatures of the lanthanide compounds were also measured. It was found that the, transition temperatures depend on the length of the a and b axis in the unit cell. A simple model considering a repulsion energy between oxygen atoms in the c plane was proposed, explaining trends in transition temperature and oxygen content.
Thick film and green sheet powder processing techniques have been studied, with application to electronic components and devices. A paste of calcined powder was made and screen-printed on various substrates. The Tcend was found to be 87K for yttria-stabilized-zirconia substrate. The ceramic body made using green sheet process had the same properties as those of the sample made using conventional powder processing techniques.View full abstractDownload PDF (911K) -
Kentaro Setsune, Kiyotaka Wasa1987 Volume 34 Issue 10 Pages 575-579
Published: December 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSHigh Tc superconducting thin films were prepared by rf magnetron sputtering. The composition of the prepared films strongly depended on the oxygen partial pressure of sputtering gas. The crystal structure of the films was determined by the substrate temperature during sputtering. The crystal growth was affected by the substrate crystal materials. Thin film of Ga-Ba-Cu-O was grown at 600°C by sputtering without suffering the postannealing. That offset temperature was 80°C with the onset resistivity of 1.6 × 10-4Ω⋅cm at 92K and the critical current density of 6 × 106 A/cm2 at 4.2K. The preparation of stoiciometric films using the proper sputtering conditions will realize the epitaxial single-crystal at the substrate temperature under 600°C and the superconductivity superiour to that of bulk ceramics.View full abstractDownload PDF (222K) -
Yasunori Ikeda, Mikio Takano, Yoshichika Bando, Hitoshi Kitaguchi, Jun ...1987 Volume 34 Issue 10 Pages 580-582
Published: December 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe subsolidus phase equilibrium in the Y2O3-BaO-CuO system at 900°C in air was determined by solid-state reaction techniques and the powder x-ray diffraction method. The system was found to contain three quaternary compounds, i.e. YBa2Cu3Ox, Y2BaCuO5, and a perovskite like solid solution having a composition of Y2xBa2-xCuOδ whose x ranges from 0.07 to 0.25. The structural symmetry of the last material changes from tetra-gonal → orthorhombic → tetragonal as x increases. Furthermore, a new ternary compound Ba2CuOx has been isolated whose structure is tetragonal K2NiF4 type with lattice parameters a=3.988A and c=12.988A.View full abstractDownload PDF (150K) -
Jun Takada, Hitoshi Kitaguchi, Akiyoshi Osaka, Yoshinari Miura, Katsua ...1987 Volume 34 Issue 10 Pages 583-589
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe decomposition process on heating and the crystallization process from a liquid on cooling for high-Tc superconductor YBa2Cu3Ox(x - 7) have been studied through thermal analysis, microstructural observation, compositional and X-ray analyses. On heating, YBa2Cu3Ox decomposes at 993°C in air to Y2BaCuO5 and a liquid due to an incongruent melting. On cooling, YBa2Cu3Ox crystallizes around the primary crystal Y2BaCuO5 from a liquid as a result of a peritectic reaction. YBa2Cu3Ox was also found to grow markedly in the sample cooled slowly to 760°C from 1200°C.View full abstractDownload PDF (2466K) -
Yoshio Oka, Naoici Yamamoto, Yoichi Tomii, Hitoshi Kitaguchi, Jun Taka ...1987 Volume 34 Issue 10 Pages 590-596
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe oxalate coprecipitation method was applied to the preparation of high-Tc superconducting oxide powder. The process of forming the oxide through the pyrolysis and subsequent heat treatment was studied in connection with powder characterization. The oxalate copreciptate, being fine powder with -0.3μm in size, consisted of Y-Ba complex and Cu oxalates. The pyrolysis proceeded mostly by three steps in the order of dehydration, decomposition of Cu oxalate and that of Y-Ba oxalate, resulting in CuO and BaC03 phases at 500°C for 2h without changing particle shape. Heat treatment avobe 850°C was favorable to obtain the oxide powder with single phase. Its particles were less than 2μm in size when treated below 925°C and drastically grew to more than 10μm above 950°C with plate-like shape.View full abstractDownload PDF (4250K) -
Zenji Hiroi, Yasunori Ikeda, Yasuo Takeda, Mikio Takano, Yoshichika Ba ...1987 Volume 34 Issue 10 Pages 597-600
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMicrostructures of the orthorhombic Ba2YCu3O7-x have been examined by high-resolution electron microscopy. The observed high-resolution images are consistent with the oxygen-deficient tri-perovskite structure determined in previous work with neutron and X-ray diffraction. Moreover, we have observed tetragonal domains coherently intergrown with the ordinary twinning ortho-rhombic ones.View full abstractDownload PDF (3719K) -
Yasuo Takeda, Ryouji Kanno, Osamu Yamamoto, Mikio Takano, Yasunori Ike ...1987 Volume 34 Issue 10 Pages 601-602
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe sintered YBa2Cu3Oy was treated at 200-600°C under high oxygen pressure(Po2=10-600atm). The samples showed no remarkable increase of oxygen content and Tc. The effect of the impurity water in oxygen gas was also studied.View full abstractDownload PDF (111K) -
Tsukio Ohtani, Tomoyuki Okudo, Atsuhiro Tamaki, Takeshi Ueda1987 Volume 34 Issue 10 Pages 603-606
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe magnetic susceptibility X of YBa2Cu3O7-x was measured from room temperature to 900 °C under oxygen pressures of 0.1, 0.2 and 0.3 atm. The change of temperature gradient of X was observed at about 600, 660 and 680 °C under 0.1, 0.2 and 0.3 atm 02, respectively. This transition was attributed to the orthorhombic-to-tetragonal transition. The ortho-II phase was obtained by quench method. Observed Pelf with variation of quenching temperature has a minimum at about 800-850 °C which origin is not clear as yet.View full abstractDownload PDF (164K) -
Hiroshi Nagai, Masaru Yokota, Kazuhiko Majima, Ken Ohobayashi1987 Volume 34 Issue 10 Pages 607-610
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSEffect of oxygen partial pressure on the phase equiliria of YBa2 Cu3 Oy at high temperature was investigated solely by electrical conductivity measurements and X-ray diffraction. Arrhenius plots of the electrical conductivities of YBa2 Cu3 Oy measured under various oxygen pressures consisted of five straight lines, whose slopes were almost the same independent of Po2. The temperatures at which the straight lines intersected corresponded to the phase transition temperatures determined by X-ray diffraction analyses and agreed with those reported by other researchers. These results suggested that the electrical conductivity measurement might be very usefull to to detect the phase transition temperatures of this material at high temperature.View full abstractDownload PDF (204K) -
Kazuhiko Majima, Masaru Yokota, Hiroshi Nagai, Ken Obayashi, Toshikatu ...1987 Volume 34 Issue 10 Pages 611-616
Published: December 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTwo kinds of YBa2Cu3Oy powders were cold pressed and sintered at 1073-1273K for 86.4ks; one is the mixed powders (M powders) and the other is the alloy powder (A powder) obtained by pulverizing the mixed powder aggregate fired at 1173K for 86.4ks, and the relation between the sintering behavior and superconducting properties were Investigated.
The sintered density ratio of A specimen was higher than that of M specimen in any cases sintered at 1073-1273K, and the highest sintered density ratio of about 90% of theoretical was obtained in the A specimen sintered at 1253K for 86.4ks, whereas the highest zero resistance temperature of 94K was observed in the specimen sintered at 1173K for 86.4ks.
The Cu rich phase other than YBa2Cu3Oy phase was detected in the M specimens sintered at 1223K and 1253K for 86.4ks, while in the A specimens sintered at the same temperatures, only YBa2Cu3Oy phase was observed.View full abstractDownload PDF (4397K) -
Hiroki Miyamoto, Kei Miyamoto, Suguru Inamura, Yuzuru Takahashi1987 Volume 34 Issue 10 Pages 617-619
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSOxygen deficiency of Ba2YCu3O7-δ was studied by thermogravimetry and thermodilatometry. Ba2YCu3O7-δ rapidly releases and adsorbs oxygen even in temperature in the vicinity of 150°C. δ was controlled by cooling specimen in O2 gas flow after annealing in Ar gas atmosphere (O2/Ar annealing) and by Ar/O2 annealing. The lattice constants a and b in the O2/Ar annealed specimen show almost constant value in the range of 0<δ<0.7, while (a-b) in the Ar/O2 annealed specimen decreases with δ. Tc of Ar/O2 annealed sample differs from that of O2/Ar annealed sample even if the samples have the same value of δ.View full abstractDownload PDF (1339K) -
Hiromasa Mazaki, Mikio Takano, Yasunori Ikeda, Yoshichika Bando, Yasuo ...1987 Volume 34 Issue 10 Pages 620-623
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe physical properties of grain boundary involved in a disk sample of sintered Ba2Y1Cu3Ox has been studied in terms of complex susceptibility. It has been revealed that the superconducting transition of the sample takes place through the concurrence of the bulk and coupled phases.View full abstractDownload PDF (185K) -
Masataka Ohkubo, Tatsumi Hioki1987 Volume 34 Issue 10 Pages 624-626
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCritical current densities and Meissner signals of sintered Ba2YCu3Oy were measured. The sample cut in water for the measurements have a small critical current density of 3 A/cm2 at 77K and a large Meissner signal of 23% at 83K to the perfect flux expulsion. With a thermal annealing, the critical current density increased to 400 A/cm2, but the Meissner signal was almost same(19%). The Meissner signals show that the volume fraction of the superconducting phase does not change with the annealing. Therefore, the increase of the critical current suggests that the connections among grains are developed with annealing.View full abstractDownload PDF (142K) -
Seiji Adachi, Osamu Inoue, Takahiro Wada, Syunichiro Kawashima, Toshih ...1987 Volume 34 Issue 10 Pages 627-631
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSY(Ba1-x-xSrx)2Cu3O7-y (0≤x≤1.0) were prepared. The temperature dependences of resistivity and ac susceptibity were measured. The annealing effect for the ceramics has been investigated. Single phase ceramics are obtained in the range of 0≤x≤0.6. The Tc decreases linearly with increasing x. The Tc scarecely changed regardless of annealing conditions, except quenching from higher temperature than 500°C.View full abstractDownload PDF (1207K) -
Masaru Yokota, Hiroshi Nagai, Kazuhiko Majima, Ken Oobayashi, Jiro Kon ...1987 Volume 34 Issue 10 Pages 632-635
Published: December 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffects of La addition substituting for Ba in YBa2Cu3O7-d on the superconductivity were investigated. Powder mixtures of Y2O3, BaCO3 (La(CO3)3) and CuO were prepared by mechanical method, cold pressed at the pressure of 98MP, sintered at 1173-1253K for 86.4 -172.8 ks and then furnace cooled in an oxygen atmosphere. For estimating the superconductivity, electrical resistivity versus temperature was measured. X-ray powder diffraction patterns were obtained by using CuK α radiation and diffractometer.
Substitution of La for Ba in YBa2Cu3O7-d resulted to lower the Tc; at about 10% La substitution for Ba, Tc dropped below 77K. ΔTc had a tendency to broaden with increasing La content. Lattice parameters of orthorombic type were changed from a = 3.884(0)(A), b =3.819(7)(Å), c =11.670(3)(Å) for YBa2Cu3O7-d to a =3.886(6)(Å), b = 3.816(8)(Å), c =11.655(9)(Å) for YBa1⋅9La0⋅1Cu7-r (L/Ba=5mass%).View full abstractDownload PDF (244K) -
Yutaka Ueda, Nobutaka Kojima, Masaaki Yoshikawa, Hiroaki Toda, Akira M ...1987 Volume 34 Issue 10 Pages 636-640
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe orthorhombic (O)-to-tetragonal (T) phase transition in RBa2Cu3O7-δ (R: Y, Sm, Eu, Gd, Dy, Ho, Er and Yb) was investigated by high temperature X-ray powder diffraction and thermogravimetry (TG) in air and O2 gases. The ortho-I phase gradually transforms to the tetragonal phase through the ortho-II phase with increas-ing temperature, accompanied with increase of oxygen vacancies. No crystallographic distinction between the ortho-I and the ortho-II phase was found. The O-T transition in all systems is of second order and the transition temperature increases with increasing atomic number of R elements.View full abstractDownload PDF (224K) -
Mitsuo Sugimoto, Koji Yamada, Eiji Kawazura1987 Volume 34 Issue 10 Pages 641-644
Published: December 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSAn attempt to prepare the iron-doped Y-Ba-Cu polycrystalline oxides, in which the preferred planes of conductivity are oriented in a magnetic field, has been curried out. For the sintered samples with the composition of (1-y)[YBa2Cu3Ox]⋅Fe2O3 (y=0.15-0.7), the marked lowering of the conductivity was prior to the increase of the magnetization with increasing concentration of Fe atoms. When Y atoms in Y1-yFeyBa2Cu3Ox (y=0.1-0.3) was replaced by Fe atoms, the change of conductivity was slight and Tc dropped to a lower temperature. No noticeable difference in the conductivity measured between the direction perpendicular to the c-axis and the direction along to that in the crystal-oriented samples. The effect of the addition of Fe atoms on the temperature dependency of resistivity, the precipitation of other phases, the magnetude of magnetization and microstructure were also investigated.View full abstractDownload PDF (1931K) -
Toshihiko Nishida, Takeshi Shiono, Takashi Ohtsuka, Tomozo Nishikawa1987 Volume 34 Issue 10 Pages 645-646
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe possibillity of the hot-extrusion processing of YBa2Cu3Or powder was examined. The starting powder was prepared from Y2O3, BaCO3 and CuO powders using the conventional ceramic procedure, and capsulated in copper bullet. The bullet was preheated at a tewperature from 700° to 1000°C for 5 minutes, and then extruded by pressing at a maximum load of about 40 ton. Hardness measurement of the ceramic after extrusion showed that the processing had a good effect on the densification of the ceramic.View full abstractDownload PDF (1078K) -
Toshihiko Shigematsu, Mariko Ishikawa, Norihiko Nakanishi1987 Volume 34 Issue 10 Pages 647-650
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe surface states of orthorhombic YBa2Cu3Ox were examined by XPS. The surface enrichment of Y and Ba was observed with the formation of surface layer, Ba and Y carbonates. The surface Y and Ba concentration decreased with the increase of Ar ion sputtering time, due to the decrease of Ba and Y carbonates. The thickness of surface layer was estimated to be as several nm.View full abstractDownload PDF (162K) -
Hitoshi Kitaguchi, Jun Takada, Akiyoshi Osaka, Yosinari Miura, Naoichi ...1987 Volume 34 Issue 10 Pages 651-658
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHigh-Tc superconductor YBa2Cu3Ox(x ≈ 6.8) reacts upon water to decompose. In order to clarify the process of decomposition, the microstructure of the YBC ceramics was studied by means of X-ray diffraction and EPMA after the reaction with water under autoclave and ambient conditions. Under the treatment in the autoclave above 100°C, the YBC ceramics were fully decomposed and Y(OH)3 or YOOH, Ba2+ and CuO were found in the solution. Due to the EPMA study on the samples treated under ambient conditions, three regions were confirmed in the grains: a) the inner core region without any interaction with water, b) the intermediate region of low Ba content surrounding the core, and c) the surface layer containing Y and Cu in the molar ratio Y/Cu=1/3 and very little amount of Ba. On these basis, it is concluded that the decomposition of the YBC ceramics is due to the diffuse-out of Ba cations to water and that the decomposition is not accompanied by the formation of Y2BaCuO5 phase.View full abstractDownload PDF (4236K) -
Masahiro Yoshimura, Seiji Inoue, Naoya Ogasawara, Yoichi Ishikawa, Tet ...1987 Volume 34 Issue 10 Pages 659-662
Published: December 25, 1987
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe instability and reactions of YBa2Cu3O7-x were studied in the presence of water. YBa2Cu3O7-x is decomposed slowly in water at room temperature, but quickly at the temperature above 100°C. The reaction products from YBa2Cu3O7-x were BaCO3, CuO, Y(OH)3, X-phase (probably to be Ba2Cu(OH)6), etc., but did not contain Y2BaCuO5.View full abstractDownload PDF (1713K) -
Yoshinari Kaieda, Tsuneo Kuroda, Hitoshi Wada, Kikuo Itoh, Tadakuni Ni ...1987 Volume 34 Issue 10 Pages 663-666
Published: December 25, 1987
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of the cold isostatic pressing in forming process on superconductivity is studied in Y-Ba-Cu-O ceramics. Ba(NO3)2, Y2O3 and CuO are mixed to the ratio of Y:Ba:Cu=1:2:3, calcined at 1173 K, mixed with and without the various amount of CuO as a binding additive, formed with cold isostatic press at various pressure and sintered at 1173 K. The critical temperature and the zero field critical current density at 77 K are measured. The values of Tc are, similar in all kinds of the specimens but the Jc is sensitive to the amount of a binding additive and the cold isostatic forming pressure.View full abstractDownload PDF (827K)
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