All issues
Volume 35, Issue 9
Displaying 1-44 of 44 articles from this issue
- |<
- <
- 1
- >
- >|
-
[in Japanese]1988 Volume 35 Issue 9 Pages 809-810
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSDownload PDF (294K) -
Hiromasa Mazaki1988 Volume 35 Issue 9 Pages 811-816
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSMeasurements of superconducting transition in terms of complex susceptibility have been well known as one of the useful methods for studying the superconducting properties of materials. By applying this method to oxide superconductors, we have found that sintered specimens consist of the bulk superconducting phase and the weak-link coupling phase. Typical experimental results observed for some kinds of oxide superconductors as well as those of thin film single crystals are presented.View full abstractDownload PDF (724K) -
Shuhei Tsuchimoto, Eizo Ohno, Hideo Nojima1988 Volume 35 Issue 9 Pages 817-820
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe galvanomagnetic effect has been studied for the ceramic superconductor Y1Ba2Cu3Ox film prepared by the spray pyrolysis method. The hysteresis behavior of the magnetoresistance and the large fluctuation of the output voltage are observed when the applied magnetic field is perpendicular to the surface of the film. However, the hysteresis disappears and the voltage fluctuation is suppressed under the applied magnetic field being parallel to the film surface. These experimental results lead to the realization of the low-noise magnetoresistor without the hysteresis property.View full abstractDownload PDF (482K) -
Koji Kosuge, Yutaka Ueda1988 Volume 35 Issue 9 Pages 821-829
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSNon-stoichiometric YBCO was newly prepared by reduction of fully oxydized samples utilizing high purity inert gases at lower temperatures. The physical measurements such as electric resistivity, complex susceptibility, electron diffraction and nuclear quadrupole resonance were performed on thus prepared samples. A schematic phase diagram on non-stoichiometric YBCO dedused from these results has been proposed.View full abstractDownload PDF (1099K) -
Ienari Iguchi1988 Volume 35 Issue 9 Pages 830-834
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe present stage of high temperature oxide superconductors for application to electronic devices is reviewed. It is pointed out that, while the operational principles including Josephson effect are verified for these new oxide superconductors and the remarkabale progress has been made for thin film fabrication techniques, there still exists a big problem to be solved to realize practical electronic devices due to special properties of these compounds such as oxygen deficiency, anisotropy etc.View full abstractDownload PDF (514K) -
Syuji Yazu1988 Volume 35 Issue 9 Pages 835-840
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSuperconducting properties of LnBaCuO(Ln: Ho, Er, Y), BiSrCaCuO and TlBaCaCuO thin films prepared by rf magnetron sputtering, using MgO single crystal substrate, were examined. The critical current densities of epitaxially grown single crystalline LnBaCuO thin filmes were excess of 3×106 A/cm2 at 77.3K. In the polycrystalline BiSrCaCuO and TlBaCaCuO thin films around the cation ratio 2:2:2:3, the critical current densities at 77.3K were 3.4×106 A/cm2 and 3.2×106 A/cm2 respectively.View full abstractDownload PDF (1050K) -
Tatsuya Yamamoto, Takayuki Furusawa, Kyung-ho Park, Mark L Green, Kazu ...1988 Volume 35 Issue 9 Pages 841-846
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe oxide superconducting ceramic Ba2YCu3O7 is sensitive to environmental degradation. The significant deterioration seen for specimens annealed in air may be attributed to the combined effect of H2O and CO2. It has been found that this degradation could be lessened by the densification of bulk superconductor prepared from co-precipitated oxalate powder. We also investigated the effect of processing and microstructual control on the critical current density of Ba2YCu3O7. Materials sintered from co-precipitated powders showed sintered densities up to 98.5% of theoretical value and were composed of a large number of plate-like grains ( 20-100μm long, 5-10μm thick ).The critical current density of highly dense samples at 77K under zero magnetic field remained at 350 Acm-2 probably due to the presence of micro-cracks. Jc of the lower density sample ( 90% ) was larger than that of the high density sample. This might be due to a decrease in a large number of micro-cracks.View full abstractDownload PDF (8732K) -
Microstructure and the Superconducting Properties in YBa2Cu3O7-x Ceramics Added with K2O-WO3 GlassesMakoto Kuwabara, Makoto Ido, Hirokazu Shimooka, Kiyotaka Hidaka, Masat ...1988 Volume 35 Issue 9 Pages 847-850
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe influence of the addition of K2O-WO3 glasses, the amount of which ranged from 0 to 20wt%, on the microstructure and superconducting properties in YBa2Cu3O7-x ceramics has been investigated. It has been found that the resistivity in the normal conducting state of the materials increased and the superconducting transition temperature decreased with the amount of the glass added. This may be interpreted in terms of the microstructural change of the materials which can be characterized by the segregation of the Cu element resulting from the addition of the glass materials.View full abstractDownload PDF (3080K) -
Knihiro NAGATA, Takahiko IWAI1988 Volume 35 Issue 9 Pages 851-855
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe effects of pore structure on the superconducting properties of dense YBa2Cu3Ox ceramics were investigated. The dense samples, 6.20 g/cm3, with many of small pores were prepared using a high calcining temperature (940°C), a planetary milling for a long time (24h) and ordinary sintering at low temperature (900°C) for 60h. The dense samples with the small pores showed larger pore-surface than the porous samples with large pores. Therefore, the dense sample facilitated the diffusion of oxygen within the material during the sintered processing, and it has become the orthorhombic structure. The resistivity and the critical current density of the dense samples increased about twice of that of the normal density samples.View full abstractDownload PDF (3118K) -
Hisatomo Yamamoto, Kunihiro Nagata, Takahiko Iwai1988 Volume 35 Issue 9 Pages 856-860
Published: December 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL FREE ACCESSWe have studied the characteristics of YBa2Cu3Ox superconducting ceramics prepared by explosive compaction using hexagon charge. The explosive compacted samples indicated the tetragonal phase and did not show superconducting until 77K. However, the compacted sample with annealing became the orthorhombic phase and showed superconducting at 82K.View full abstractDownload PDF (3306K) -
Seiji Yamada, Takao Ogawa, Takeshi Miki, Hideyasu Tsuiki, Noriyoshi Ka ...1988 Volume 35 Issue 9 Pages 861-864
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSuperconductive films composed of Ba2YCu3O7-X were prepared by fume pyrolysis with a temperature programmed electric furnace. Fumes generated from an aqueous solution of Ba, Y and Cu nitrates with an aid of supersonicant were introduced into the furnace with flowing O2. Fine particles consisting of Ba, Y and Cu ions were formed in the furnace and deposited on the surface of a YSZ substrate placed at the top of the furnace. Films thus prepared and annealed at 1273 K showed superconductive properties below 90 K and zero resistivity was observed at 80 K with 100 uA of the current.View full abstractDownload PDF (585K) -
Yoshio Masuda, Tsuyoshi Tateishi1988 Volume 35 Issue 9 Pages 865-869
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSYBa2Cu3Ox superconducting fibers were fablicated from a solution of Y.Ba alkoxides and Cu acetate through sol·gel method. Homogeneous viscous sol was prepared by hydrolysis of the solution under acidic condition and holding 60-80°C. Gel fibers of 10μ-1mm in diameter and more than 5m in legth could be draw from the sol. Dense ceramic fibers were obtained by heating the gel fibers to 400°C at a slow rate of 10°C/h and sintering at 950°C. These fibers showed the diamagnetism below 95K.View full abstractDownload PDF (4980K) -
Takahito Terashima, Yoshichika Bando, Kenji Iijima, Kazunuki Yamamoto, ...1988 Volume 35 Issue 9 Pages 870-874
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe orientation of YBa2Cu3O7-x thin films grown on (110) planes of SrTiO3 by activated reactive evaporation was investigated by means of reflection high energy electron diffraction. The orientation of the films depended on the substrate temperature. The films with the (110) plane parallel to the substrate surface grew in the narrow range of substrate temperatures around 530°C, while the films with the (103) plane parallel to the surface grew at the temperatures above 600°C. The change of the epitaxial orientation with the substrate temperature was discussed refering the temperature dependence of the lattice mismatch between YBa2Cu3O7-x and SrTiO3.View full abstractDownload PDF (2453K) -
Toshihiko Shigematsu, Norihiko Nakanishi1988 Volume 35 Issue 9 Pages 875-878
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSBa2YCu3Ox was prepared by the vacuum calcination and subsequent oxidation of Ba2YCu3Ox prepared by a conventional ceramic method. Surface state of this sample was examined by the X-ray photoelectron spectroscopy. During the vacuum calcination up to 1200 K. two temperature maxima in the deoxidation rate were observed at around 670 K and 1170 K. First peak was correspond to the orthorhombic to tetragonal phase transition in Ba2YCu3Ox and second peak came from the reduction of Cu2+ to Cu1+ accompanied by the decomposition of Ba2YCu3Ox. This sample was easely oxidized in oxygen atmosphere at around 1173 K. After the vacuum calcination and subsequent oxidation, the surface condensation of Ba and Y usually observed in Ba2YCu3Ox prepared by the conventional ceramic method was eliminated. This came from the evolution of CO2 from carbonate ion remained at the surface layer of Ba2YCu3Ox occurred during the vacuum calcination.View full abstractDownload PDF (589K) -
Hiroaki Toda, Yutaka Ueda, Koji Kosuge1988 Volume 35 Issue 9 Pages 879-884
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSmBa2Cu3Oy and GdBa2 Cu3Oy with various y have been prepared by quenching and by the reduction in N2 gas, and their superconducting properties were examined by electrical resistivity and χao measurements. The superconducting transition temperature Tc1' determined by χao seems to decrease stepwise with decreasing y. This suggests the existence of 60 K-class superconductor, similar to YBa2Cu3Oy.View full abstractDownload PDF (490K) -
Hiroshi Okada, Teiji Kusaka, Zenji Hiroi, Mikio Takano, Yasuo Takeda1988 Volume 35 Issue 9 Pages 885-890
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe phase change of the non-superconducting tetragonal- I ' phase(YBa2Cu3O6.76) by annealing in oxygen atmosphere was studied.Tetragonal-III(YBa2Cu3O7.06) and Orthorhombic-III(YBa2Cu3O7.11) are formed under the annealing conditions:(1)900°C×2hr+400°C×10hr and (2)400°C×100hr, respectively.Examination with a high resolution electron microscope revealed that T- I ' has homogeneous tetragonal structure without any microdomain structure. However T-III has partial inhomogeneity which is caused by microdomain structure or twinning. O-III has homogeneous orthrhombic structure with slightly different a and b axes. T-III and O-III show the superconducting transition at 92K and 60K, respectively as obtained by magnetic susceptibility measurements. The set of results supports the importance of ordering of oxygen in the Cu(1)-O chain site for the occurrence of the high temperature superconductivity in the Y-Ba-Cu-O system.View full abstractDownload PDF (918K) -
Synthesis snd Superconducting PropertiesShigeru Katsuyama, Yutaka Ueda, Koji Kosuge1988 Volume 35 Issue 9 Pages 891-895
Published: December 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL FREE ACCESSThe compound YBa2(Cu1-xFex)3Oy with the orthorhombic structure was successfully prepared in the wide composition range (0≤x<0.15) by a new preparation method, and the superconducting properties were examined. This orthorhombic phase shows the superconducting transition near 90K even for x=0.12 and shows the orthorhombic-to-tetragonal phase transition on heating. The stabilization of the orthorhombic phase seems to be due to the arrangement of Fe ions in the Cu1-O planes.View full abstractDownload PDF (625K) -
Microscopic StructureShigeru Katsuyama, Yutaka Ueda, Koji Kosuge1988 Volume 35 Issue 9 Pages 896-901
Published: December 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL FREE ACCESSYBa2(Cu1-xFex)3Oy with the orthorhombic structure was prepared in the wide composition range (0≤x<0.15) by heating in pure N2 gas followed by annealing in O2 gas below 400°C. The stabilization of the orthorhombic phase was discussed in terms of the arrangement of Fe ions in the Cu1-O planes. 57Fe Mossbauer measurements were performed on the five samples of YBa2(Cu0.96Fe0.04)3Oy which were prepared by the different thermal treatments. As the results, Fe ions occupy both Cu1 and Cu2 sites and the substitution of Fe ions for Cu ions in the Cu2 sites is little affected on the superconducting properties of YBa2Cu3Oy.View full abstractDownload PDF (709K) -
Tsukio Ohtani, Tatsumi Uemura, Kazuo Ohkuma, Yasuhiro Oh-hashi, Hiroyu ...1988 Volume 35 Issue 9 Pages 902-905
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSeebeck coefficients (S) of undoped YBa2Cu3O7-y (YBCO) are negative below about 500°C and changes the sign to plus around 500°C, followed by the sharp increase with temperature up to 900°C. Fe, Co, Ni and Zn are substituted for Cu, La and K for Ba, and Ca for Y. The values of S of impurity-substituted YBCO show the strong dependence on the valency of substituted atoms.View full abstractDownload PDF (487K) -
Hiroshi Terada, Toshiyuki Ido, Saburo Muto1988 Volume 35 Issue 9 Pages 906-910
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSTo realize the application of the High Tc superconductor, there are several things to keep in mind. One is the application of electric power systems. There are many attempts being made from many sides in anticipation of this wiring. For example one way is to pack the High Tc superconductor with Ag, Cu or stainless steel pipe with thin line processing. But as this High Tc superconductor is hard and fragile so to wire it is difficult. When "Ag" is added, processing and the superconductor characteristic is improved. Discussed in this report was the effect of "Ag" added to YBa2Cu3Oy superconductor and its electric properties.View full abstractDownload PDF (2487K) -
Masaru Yokota, Hiroshi Nagai, Kazuhiko Majima, Ken Obayashi1988 Volume 35 Issue 9 Pages 911-914
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSubstitution effect of La for Y or Ba in Y1Ba2Cu3Oy sintered ceramics on their magnetic susceptibility of YBaCuO sintered ceramics was investigated by using dc magnetic balance ranging from 500 to 8325 Oe of magnetic fields. 5 mol% of La was substituted for Y(named YLBCO) or Ba(YBLCO) in Y1Ba2Cu3Oy(YBCO); (1) Onset temperature of Meissner effect in these three specimens lowered with the increase of magnetic field. (2) Magnetic susceptibility of these specimens at 77K in the magnetic fields ranging from 500 to 8325 Oe increased in the following order: YBCO, YBLCO, YLC. (3) Volume fraction of superconductive phase in these specimens at 500 Oe were etimated to be about 3% and 4% for YBCO and YBLCO, and YLBCO, respectively.View full abstractDownload PDF (440K) -
Zenji Hiroi, Mikio Takano, Yoshichika Bando, Yasuo Takeda1988 Volume 35 Issue 9 Pages 915-918
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSMicrostructures of YBa2Cu3Oy with y=6.50, 6.75 and 6.85 as studied by high-resolution electron microscopy all consist of two kinds of thin parallel plates having different 2(b-a)/(b+a) values of 0% and 3-4%, where a and b are the lattice constants of the basal plane. These plates appear alternately along the [110] direction in a period of several tens of nm, while the ordinary orthorhombic twin structure with 2(b-a)/(b+a)=2% results at y=6.9. A two-phase region spreading over a wide temperature range for 6.50_??_y_??_6.85 has been concluded.View full abstractDownload PDF (3192K) -
Shuichi Iida, Toshiharu Mitsui, Kiyoshi Abe1988 Volume 35 Issue 9 Pages 919-922
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSAnalysis has been developed on the mechanism of the high temperature superconductivity of oxides by using the theoretical framework of the new frames in physics. Various characters of electron fields are investigated. A new physical concept called "the Mobius state", such as, spin Mobius, orbital Mobius or spin-orbit coupled Mobius state, is introduced. Importance of the phase factor of the electron field has been emphasized, which can explain the Larmor diamagnetism and the Meissner effect by a few equations, A fundamental dispersion relation on the proposed coherent photonelectron field complex has been derived, The result is presented in the ω-k plane, which indicate that 3√n/m << 4.82×1039(n:electron density; m: effective mass;4.82×1039 is a simple value for Cu) might be crucial for obtaining the enhanced photon-electron coherent complex, so that, the occurrance of the high temperature superconductivity, A short review on our experimental results of PbBiSrCaCu-O system is added.View full abstractDownload PDF (659K) -
Yasuo Takeda, Ryouji Kanno, Fumiyoshi Tanigawa, Osamu Yamamoto, Mikio ...1988 Volume 35 Issue 9 Pages 923-926
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSAnnealing effect of Pb doped 2223 type superconductor Pb0.35Bi1.73Sr1.89Ca1.86Cu3.0Oy under high oxygen pressure at 200 - 600 C are reported. Annealing under 100 atm of oxygen increased oxygen content and shortened the c-axis with a few degree drop in Tc. On the other hand, lead-free 2223 phase showed no change in cell parameters and Tc, but an increase in the oxygen content. It is possible that oxygen atoms enter in Bi2O2 layers and bismuth and lead are partially oxidized.View full abstractDownload PDF (441K) -
Hiroki Miyamoto, Kei Miyamoto, Suguru Inamura, Yuzuru Takahashi1988 Volume 35 Issue 9 Pages 927-929
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSHigh Tc phase with c=3.7 nm of Bi-Sr-Ca-Cu-O system was synthesized from a starting composition 2234 by repeating powdering and sintering alternately.
When the powdering-sintering cycles were repeated four times with total sintering time of 350 h, the amount of the high Tc phase in the specimen was larger than 95 % from XRD measurement. Tcoffset of the specimen was 95 K. The high Tc phase formed at a temperature higher than the melt appearing temperature of the starting powder.View full abstractDownload PDF (474K) -
High-Temperature X-ray Measurements on Bi-Sr-Ca-Cu-O Superconductors in the Partially Melting StatesYoshio Oka, Naoichi Yamamoto, Youichi Tomii, Hitoshi Kitaguchi, Kiichi ...1988 Volume 35 Issue 9 Pages 930-933
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSHigh-temperature X-ray measurements were carreid out in the Bi-Sr-Ca-Cu-O system to investigate the partially melting states in which the high Tc phase (37 A phase) is produced by heat treatment. Two samples with 2212 and 4336 compositions were examined as the representatives of non-forming and forming the 37 A phase by heat treatment. respectively. The inconguruent melting was found to take place in both samples to give new crystalline phases coexisting with liquid phases. It was noted that the new crystalline phases of the two samples were different from each other. It is thus suggested that the crystalline phase of the 4336 sample reacts with the liquid and the 30 A phases in the partially melting state to produce the 37 A phase. In the cooling process. the 30 A phase was crystallized at the solidifying temperature and then the 24 A phase appeared at the lower temperature for both of the compositions.View full abstractDownload PDF (441K) -
Hiroshi Nagai, Masaru Yokota, Kazuhiko Majima, Ken Ohobayashi, Masahir ...1988 Volume 35 Issue 9 Pages 934-936
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe high temperature behavior of BiSrCaCu2 Oy was investigated by electrical resistivity measurement in relation to superconducting properties. A hysteresis was found between on heating and cooling processes in the temperature dependence of the electrical resistivity. The hysteresis occurred at about 550-700°C for the samples with high content of low Tc phase (80 K), while the hysteresis occurred at higher temperature(700-800 °C) for the samples with higher content of high Tc phase(105 K). These results suggest that the hysteresis in the temperature dependence of electrical resistivity may be related to the difference in the concentration ratio of high Tc phase to low Tc phase. Further detailed research is in progress.View full abstractDownload PDF (391K) -
Osamu Inoue, Seiji Adachi, Yukihiro Takahashi, Hirofumi Hirano, Syunic ...1988 Volume 35 Issue 9 Pages 937-940
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSFormation of 37Å phase in Bi-Sr-Ca-Cu-O ceramics was accelerated by milling and re-sintering of sintered body. The ceramics which almost consists of 37Å phase by this method has small grain size compared with no milling ceramics. The supercondictive property of the Bi2Sr2Ca2Cu4Ox ceramics was depressed by the milling and re-sintering method though it has large volume fraction of 37Å phase.View full abstractDownload PDF (2090K) -
Kazuhiko Majima, Hiroshi Nagai, Masaru Yokota, Ken Obayashi, Atsushi T ...1988 Volume 35 Issue 9 Pages 941-944
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSIn order to get a single high-Tc phase in the simple Bi-Sr-Ca-Cu-O system without any other element, two kinds of powders: one named A obtained by pulverizing of the mixed powder aggregate fired at 850°C for 24h and the other named B obtained by oxalate coprecipitation method, were used in this experiment, and the effect of sintering time and temperature on the superconductivity have been studied.
Whereas most of the specimens sintered at 860-880°C for 24h or 288h showed a two step resistivity transition (at about 110K and at about 80K), one specimen using A powder sintered at 877°C for 288h showed a sharp single resistivity transition at about 110K and zero resistance at about 100K. X-ray diffraction pattern, however, showed that the low-Tc phase still remained even in this case.View full abstractDownload PDF (4102K) -
Hitoshi Kitaguchi, Jun Takada, Kiichi Oda, Akiyoshi Osaka, Yoshinari M ...1988 Volume 35 Issue 9 Pages 945-951
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSuspension effect of a high-Tc Bi-Pb-Sr-Ca-Cu-O superconductor beneath the doughnut-shaped permanent magnet was examined by means of a improved magneto-balancing method at 77K. The observed values of both the suspension position and the force exerted upon the superconductor specimen were in good agreement with those calculated from the magnetization curve of the specimen and the intensity of the magnetic field of the used permanent magnet. Obtained results indicate that the origin of suspension effect in the present case is mainly due to Meissner effect, and a little different from the pinning force reported so far.View full abstractDownload PDF (696K) -
Jun Takada, Masashi Ohno, Hitoshi Kitaguchi, Kiichi Oda, Akiyoshi Osak ...1988 Volume 35 Issue 9 Pages 952-958
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSEquilibrium phase relationships for the pseudo-ternary systems Bi2O3-PbO-CaO and Bi2O3-PbO-SrO at 873K and 1073K in air have been studied mainly by the powder X-ray diffraction method. At 1073K, the regions of liquid or liquid plus solids were determined in the both systems. In these systems we found two new solid solutions ( α and β ) and two new compounds ( Bi8Pb7Ca2Ox and Bi8Pb9Sr3Ox ). Two new compositions Bi3Ca2Ox and Bi11Pb4Ox were proposed instead of Bi10Ca7O22 and Bi3PbOx already reported, respectively.View full abstractDownload PDF (828K) -
Kiichi Oda, Hitoshi Kitaguchi, Jun Takada, Akiyoshi Osaka, Yoshinari M ...1988 Volume 35 Issue 9 Pages 959-964
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSIn order to prepare the single high-Tc phase in the Bi-Pb-Sr-Ca-Cu-O system, the chemical compositions and the heat treatment conditions were examined. The addition of the excess amount of calcium and the two-step heat treatment were more effective to promote the formation of the high-Tc phase and to shorten the heat treatment time. The sample with the nominal composition of Bi0.96Pb0.24Sr1.0Ca1.1Cu1.6Oxheat treated at 850°C for 24h-70h was mostly composed of high-Tc phase. The content of Pb in the sample was considerably decreased by the heat treatment and reduced to 1/2-1/3 of its initial value.View full abstractDownload PDF (785K) -
Yasunori Ikeda, Hiroyuki Ito, Zenji Hiroi, Mikio Takano, Hitoshi Kitag ...1988 Volume 35 Issue 9 Pages 965-969
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe preparation and characterization of Pb0.18Bi0.93Ca1.02Sr1.02Cu1.6Ox, a lead-rich high-Tc phase, were studied (T(ρ=0)=105K). This compound crystallized in a pseudotetrag onal sturucture with at=0.541nm and ct=3.709nm, while a unique one-dimensional modulation with a wavelength of 4.7nm (_??_8.7b) was found along the b axis using transmission electron microscopy. This phase is not stabilized at lower temperature in air. It decomposes to the lead-free (or poor) high-Tc phase crystallizing in the convetional modulated structure 2.7nm(_??_5b).View full abstractDownload PDF (1706K) -
Katsuyoshi Hotta, Toshimasa Suzuki, Haruo Hirose, Yoshihiro Koike1988 Volume 35 Issue 9 Pages 970-973
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSuperconductors(Tc=110K) have been synthesized in the process of researching fundamental conditions of preparation with starting composition of Bi0.7Pb0.3SrCaCu1.8Oy. The measurements and analysis such as electrical resistivity, X-ray diffraction, DTA, SEM and micro-Raman scattering have led to the conclusion: 1)the sintering condition of 830°C, 244 hours produces superconductor of Tc=110K, 2)this system shows an abnormal behavior in electrical resistivity near 145K, 3)X-ray diffraction analysis suggests that with increasing in sintering period of time, high-Tc phase increases in its ratio to low-Tc phase, 4)DTA result indicates that the best sintering is realized at the temperature at which the possible peritectic reaction may begin.View full abstractDownload PDF (2016K) -
Masahiro Yoshimura, Tae-Hyun Sung, Shigeru Arima, Yutaka Ohya, Sakae T ...1988 Volume 35 Issue 9 Pages 974-978
Published: December 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL FREE ACCESSSubstitution of Cd for Ca in Bi2Sr2Ca2Cu3Oy has been studied by using rapid quenching after rapid melting technique. Amorphous materials containing a small amount of CaO phase were obtained as films with about 20 μm thickness. Annealing of the films for Bi2Sr2Ca2-xCdxOy at 870°C for 5 hr in air yielded a superconducting phase with co= 3.0 nm in the composition of x≤0.5. Tc(endpoint) increased and tailing of transition disappeared with increasing Cd contents. A maximum Tc(endpoint) value of 87 K was obtained at the composition of x=0.4. Further substitution of Cd for Ca brought about lowering in Tc, because a semiconducting phase with co = 2.5 nm was formed instead of co = 3.0 nm phase.View full abstractDownload PDF (531K) -
Yutaka Iwai, Atsushi Ito, Masasuke Takata, Tsutomu Yamashita, Mamoru I ...1988 Volume 35 Issue 9 Pages 979-983
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSFrequently, as-sintered specimens having 2223 phase in Bi-Pb-Sr-Ca-Cu-O system do not show the critical temperature higher than 100K. The effects of additional heat treatments on the microstructures and electrical properties of these specimens were investigated. Remarkable improvements in the critical temperature and critical current density were achieved by additional sintering.View full abstractDownload PDF (5109K) -
Akira Kikuchi, Motohide Matsuda, Masasuke Takata, Tsutomu Yamashita, M ...1988 Volume 35 Issue 9 Pages 984-988
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThe influence of the processing on the superconducting characteristics was investigated for the new high-Tc Bi-Pb-Sr-Ca-Cu-O ceramics. The critical temperature Tc, zero and the critical current density Jc at 77K under zero magnetic field were strongly dependent on the sintering temperature. Further, the Jc was also dependent on the sintering time. The specimen sintered at 845°C for 90h showed maximum values of 105K and 56A/cm2.View full abstractDownload PDF (5781K) -
Tomoaki Matsushima, Kumiko Hirochi, Kentaro Setsune, Kiyotaka Wasa1988 Volume 35 Issue 9 Pages 989-992
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThin films of Bi-Sr-Ca-Cu-O system were prepared at the substrate temperature between 550°C and 600°C. The film deposited at 570°C showed X-ray diffraction pattern of Bi2Sr2Ca2Cu3Oy phase and had a zero resistance temperature Tc at 23K. After annealing at 570°C under the oxygen pressure of 1 atm, zero resistance temperature Tc increased to 45K, but under the pressure of 0.1 atm, the crystal structure was changed and nonconducting Ca-Cu-O phase appeared.View full abstractDownload PDF (415K) -
Masataka Ohkubo1988 Volume 35 Issue 9 Pages 993-996
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSThin films of the BiSrCaCuO system have been synthesized by the multilayer deposition method followed by annealings in oxygen. Four phases, three being pseudotetragonal with c lattice parameters of 37, 30, 24Å and one may being c=19Å have been observed with X-ray diffraction and resistance measurements. The temperature ranges for the formation of each phase have been determined.View full abstractDownload PDF (445K) -
Masayoshi TONOUCHI, Yoshito FUKUMOTO, Takeshi KOBAYASHI1988 Volume 35 Issue 9 Pages 997-1000
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSEffect of element addition on the superconductivity of rare-earth-element-free high Tc superconductors has been investigated. The element was chosen out of the IIa group. The measurement of the superconductivity revealed that the addition of the appropriate amount of Mg together with Cu was effective to rise the zero-resistance temperature of the Bi compounds.View full abstractDownload PDF (504K) -
Jun Takada, Hitoshi Kitaguchi, Kiichi Oda, Akiyoshi Osaka, Yoshinari M ...1988 Volume 35 Issue 9 Pages 1003-1009
Published: December 25, 1988
Released on J-STAGE: January 15, 2010
JOURNAL FREE ACCESSThe effect of Ba addition on the formation and the critical temperature Tc of the high-Tc superconductor in the Bi, Pb-Sr-Ca-Cu-O system was studied. A series of samples Bi0.7Pb0.3Sr1-αBaαCaCu1.8Ox were prepared by the conventional ceramic method. High-Tc phase ( c ≅ 37Å ) was formed without coexistance of low-Tc phase ( c ≅ 30Å ) and 24Å phase in the sample of α ≤ 0.5 by the heat treatment at 845°C for 45-140h even though BaPb0.75Bi0.25O3 and (Sr, Ca)3Cu5Ox were a little remained. The electrical resistance of the sample with a composition of α=0.1 heated at 845°C for 140h dropped to zero at 105K and diamagnetic response was also observed. It was found that the addition of a small amount of Ba promoted the formation of high-Tc phase but Ba2+ ion was hardly substituted in the high-Tc phase.View full abstractDownload PDF (1032K) -
Masaru Yokota, Hiroshi Nagai, Kazuhiko Majima, Koichi Kanbara, Ken Oba ...1988 Volume 35 Issue 9 Pages 1010-1013
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSPossibility of grain orientation controlling and activated sintering by thermal diffusion treatment (named heterogeneous sintering) was studied for the superconductive Y1Ba2Cu3Oy ceramics, starting raw materials were mixed powder compacts of Y2O3, BaCO3 and CuO. Heating rate, upper surface temperature, effective temperature gradient, sintering time and cooling rate were approximately, 2K/s, 1240K, 10K/s, 1.8 ks18 ks and 1.4K/s at 750K, respectively; (1) The grains in Y1Ba2Cu3Oy ceramics produced by thermal diffusion treatment were found to be oriented with the c-axis along a heat flow direction, showing a fairly well-oriented grain structure.
(2) Clear differences in temperature dependent electric resistivity between heterogeneously and homogeneously (conventionally) sintered ceramics were recognized as; Critical temperature (Tconset)of superconductivity for the sample which was hetrogeneously sintered for 1.8 ks and cooled at 1.4 K/s in air was both 90 K for the A-B plane (perpendicular to a heat flow direction) and the C-plane (parallel to a heat flow direction). Contrary to this, Tconset for the sample which was homogeneously sintered under the same condition as the above has never appeared in the temperature range down to 77K of liquid nitrogen temperature.View full abstractDownload PDF (497K) -
Kanji Tsuchida, Masasuke Takata, Tsutomu Yamashita, Mamoru Ishii, Hide ...1988 Volume 35 Issue 9 Pages 1014-1019
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSSuperconducting thin films of Bi-Sr-Ca-Cu-O system have been prerared on MgO substrates by RF-magnetron sputtering using Bi1Sr1Ca1Cu2Ox powder target. The as-sputtered films deposited at room temperature were amorphous insulators. After annealing, the films exhibited a superconducting transition at about 80K and characteristics of the films changed remarkably. The effect of the annealing process on superconductivity, surface condition, composition and orientation of the films were investigated.View full abstractDownload PDF (4677K) -
Toshihisa Asano, Hiroshi Maeda1988 Volume 35 Issue 9 Pages 1020-1023
Published: December 25, 1988
Released on J-STAGE: May 29, 2009
JOURNAL FREE ACCESSBulk superconductors of Bi oxide system dominated with the high-Tc phase and a highly oriented microstructure is obtained by a powder method inserting an intermediate pressing process. The critical current density, Jc is improved by this uniaxial pressing by one order of magnitude or the more than that of unpressed sample. The field dependence of Jc is also improved.View full abstractDownload PDF (2417K)
- |<
- <
- 1
- >
- >|