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Volume 37, Issue 5
Displaying 51-59 of 59 articles from this issue
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Tadashi Kikuchi, Atsushi Koike, Keiichi Furuya, Shuji Yoshizawa1990 Volume 37 Issue 5 Pages 788-791
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSCharacterization of supercondunctor material has been investigated by means of thermal desorption mass spectrometry and oxygen quantification. From the results, the oxygen content increased with the decrease of grain size of the specimen. The oxygen content of the specimen which grain size is 3μmφ is 6% higher than the specimen which grain size is 150μmφ. On the smaller grainsize specimen, gas extraction takes place in the quite 500°C region. Extracted gases from these specimens mainly consist of oxygen and water vapor.
The obtained results show that oxygen in these samples were at least more than four states depending on the grain sizes.View full abstractDownload PDF (224K) -
Toshihiko Shigematsu, Tomohiro Furukawa, Norihiko Nakanishi1990 Volume 37 Issue 5 Pages 792-794
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNon-stoichiometric YBa2Cu3Oy with the wide composition range (6.15≤y≤6.8) was prepared by the reduction of samples with y??7.0 in a vacuum at around 400°C. The orthorhombic to tetragonal phase transition occurred at y??6.2 at 400°C.View full abstractDownload PDF (140K) -
Hiromasa Mazaki, Hiroshi Yasuoka, Kazunuki Yamamoto, Shigeru Katsuyama ...1990 Volume 37 Issue 5 Pages 795-798
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSTemperature dependence of ac-susceptibility including the higher-harmonic terms was investigated for sintered specimen of high-Tc oxide superconductor. An intrinsic granular component and an intergranular coupling component were observed in the real part of fundamental susceptibility. In the latter component region, the imaginary part of fundamental susceptibility formed a single peak, and real and imaginary parts of higher-harmonic terms also had finite values. The results observed were coinside with those computed on the basis of the Kim-Anderson model supposed that the constant Be have a finite value. Physical meaning and fitness of the model were discussed.View full abstractDownload PDF (261K) -
Kazunuki Yamamoto, Kazuto Hirata, Kenji Iijima, Katsuhiko Hayashi, Hir ...1990 Volume 37 Issue 5 Pages 799-802
Published: July 25, 1990
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSMagnetic response of YBCO superconductors was investigated in terms of ac-susceptibility including higher-harmonics χn=χn′-i⋅χn″ (n=1, 2, 3, …). Two types of specimens, bulk and thin films of single crystal, were used. χn versus temperature curves observed exhibited peculiar properties to the types of. specimens. The results observed are qualitatively reproduced by the curves calculated on the basis of the Kim-Anderson model for the bulk specimen or the modiflied Bean model for the thin films. This is understood that vortex pinning inside the specimen or surface barrier plays an important rule on the magnetic response for the former or the latter, respectively.View full abstractDownload PDF (279K) -
Yuuichi Ishikawa, Masahiro Kojima, Shuichi Kohayashi, Yasuko Mashima, ...1990 Volume 37 Issue 5 Pages 803-806
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe magnetic and electrical properties of polycrystalline YBaCuO prepared by sintering various size of powders were examined by DC four-probe method and vibrating sample magnetometer(VSM). As magnetic properties, initial magnetic curves and hysteresis curves were measured and gradients of initial magnetic curves were calculated. Effects of shielding magnetic field were studied with YBaCuO pellets of 1 inch in diameter and 1 mm in thickness by hall generator(F.W.BELL) at DC magnetic field bellow 200 gauss. Increasing magnetic field, shielding was broken at about 20 gauss and transmitted magnetic field was constantly from 20 to 30 gauss less than applied magnetic field above 20 gauss. But transmitted magnetic field decreased as the value of magnetization increased. It may be concluded that shielding effect is dependent on magnetization rather than critical current density at low magnetic field.View full abstractDownload PDF (191K) -
Masahiro Kojima, Yuichi Ishikawa, Shuichi Kohayashi, Yasuko Majima, Sh ...1990 Volume 37 Issue 5 Pages 807-810
Published: July 25, 1990
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMagnetic properties of Y1Ba2Cu3Ox. powders pulverized into different particle size were measured by using Vibrating Sample Magnetometer(VSM). The lower critical magnetic field H cl increased with decreasing powder size corresponding to view of thermodynamics. The external field and particle size dependence was obtained from the time decay rate of magnetization and zero-field cooling (Shielding Effect) and field cooling (Meissner Effect) measurement. It showed presence of low field region where the gradient of magnetic field density in grain is rather clear.View full abstractDownload PDF (1013K) -
Keizou Tsukamoto, Hiromasa Shimojima, Mamoru Ishii, Chitake Yamagishi1990 Volume 37 Issue 5 Pages 813-816
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe Bi-Pb-Sr-Ca-Cu-O thin films with different (Bi+Pb) content were prepared on non-heated MgO single crystal (100) by rf magnetron sputtering using multi targets ; Bi0.5Pb0.5Ox, CaCu0.75Ox, SrCu0.75Ox. The obtained amorphous films were annealed to crystallize. Most of the samples which were annealed at 832-836°C for 65 hours showed high Tc(Tc>100k). Jc of these films was very sensitive to annealing temperature and varied from nearly 0 to 1187 A/cm2 (at 77K and in zero magnetic field). The change of Jc for annealing temperature depended on the film composition. The more grains in the films grew coarsely, the more Jc was decreased. We suggested that the low Jc of the films withcoarsemorphology was caused by small superconducting current path areaView full abstractDownload PDF (1060K) -
Kohmel Halada, Satoru Ohno, Hideo Okuyama, Takehiro Dan, Yuji Muramats ...1990 Volume 37 Issue 5 Pages 817-819
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSMelting behavior of BSCC(2:2:2:3) oxide was directly observed. Pressed pellet of BSCC oxide was heated on the plate of BN, Al2O3, MgO or Ag in the air. Liquid phase appeared at 882°C and remaining solid phase vanished above 957°C on MgO and Al2O3, contact angle on which were zero and 10 respectively at 972°C. BN was found to react with oxide above 840°C. Ag lowered the melting temperature.View full abstractDownload PDF (2223K) -
Kazuhiro Yamaguchi, Hirotugu Susami, Kenji Ishizaka, Akira Doi, Toshio ...1990 Volume 37 Issue 5 Pages 820-824
Published: July 25, 1990
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe XRD experiments and the measurements of electrical resistivity were conducted for the sample with a composition of Bi : Pb : Sr : Ca : Cu = 0.7 : 0.3 : 1.0 : 1.0 : 1.8 heated at temperatures from 842 to 849°C for 120h. Partial melting in the samples calcined at 800°C for 12h occurs at 835 °C, being much lower compared with that in the samples with compositions for the high-Tc monophase reported so far. Relative volume fraction of the high-Tc phase gradually increases as heating temperature increases below 846°C, while markedly increases at 847 and 848°C. Tc also depends upon the heating temperature. The samples heated at temperatures below 846°C shows Tc around 105K. Tc reaches 110K for the samples heated at 847 and 848°C. These results reveal that optimum temperatures for Tc and the formation of the high-Tc phase are 847 and 848 °C just below the decomposing temperature of the low-Tc phase.View full abstractDownload PDF (1144K)