巻号一覧
38 巻, 8 号
選択された号の論文の26件中1～26を表示しています
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坂東 尚周1991 年 38 巻 8 号 p. 986
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーPDF形式でダウンロード (57K) -
高野 幹夫1991 年 38 巻 8 号 p. 987-990
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーEffects of high pressure on the formation, structure, and electrical and magnetic properties of Cu-oxides crystallizing in perovskite-related structures have been studied. Under 6GPa at 1223K ACuO2 (A: Ba1/3Sr2/3-Sr1/3Ca2/3) is stabilized in the Ca0.84Sr0.16CuO2 type structure and R2CuO4 (R: Y, Dy, Ho, Er, Tm) in the Nd2CuO4-type structure. Very recently superconductivity with Tc=50K - 100K has been detected in the A-Cu-O system free from any rare earth ion, Bi3+, and Tl3+, treated at 6GPa and -1273K.抄録全体を表示PDF形式でダウンロード (217K) -
沢野 清志1991 年 38 巻 8 号 p. 991-995
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーLarge bulk YBaCuO superconductors prepared by melt processes exhibit unique macro properties such as strong repulsion of a permanent magnet and high magnetic flux density trapping. These properties are explained by the total pinning force of the bulk. Since sintered polycrystalline bulk materials include many weak links such as grain boundaries, the total pinning force is weak. As melt-processed bulk materials have much less number of grain boundaries, the total pinning force increases. These properties were further improved by elimination of grain boundaries in the large bulk superconductors. This was enabled by additional techniques to the melt processes such as seeding and unidirectional growth. Applications of the bulk superconductors have been proposed such as noncontact transportation bulk magnets and bearings. Although the possibility of these applications is not clear, the future of the bulk superconductors is expected to be hopeful.抄録全体を表示PDF形式でダウンロード (3057K) -
榎本 陽一, 浅野 秀文, 久保 衆伍, 山路 昭彦1991 年 38 巻 8 号 p. 996-1000
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーWe have fabricated a contact junction between an epitaxially grown YBa2Cu3O74 thin film and a polycrystalline Ba ?? xKxBiO3 thin film. This contact junction shows the typical I-V characteristics of quasi-particle tunneling which are observed for junctions consisting of electrodes having different superconducting energy gaps. From the I-V characteristics, the superconducting energy gap, 2Δ, is estimated to be 1.5 meV along the c-axis for YBa2Cu3O74 and 3 meV for Ba ?? xKxBiO3+ The 2Δ/kTc for the Ba ?? xKxBiO3 is about 3.5, which is equal to that derived from a boundary Josephson junction. These properties show that the contact boundary between YBa2Cu3O74 and Ba ?? xKxBiO3 works as the tunneling barrier.抄録全体を表示PDF形式でダウンロード (262K) -
武田 保雄, 佐藤 敦, 今西 誠之, 山本 治, 広井 善二, 高野 幹夫, 坂東 尚周1991 年 38 巻 8 号 p. 1001-1004
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーLa2-xBixCuO4+z (0<x<0.2) was prepared under oxygen pressures between 1bar and 0.5kbar. The solid solution La2-xBixCuO4+z showed superconductivity only after being annealed under high oxygen pressure. For La2CuO4+z the superconducting transition temperature, Tc, was almost independent of z at around 40K, while the Tc of Bi-doped samples showed a strong dependence. The superconductive volume fraction was considersbly increased by the Bi doping. The known phase separation into nearly stoichiometric La2CuO4 and superconducting La2CuO4+z seems to be suppressed by the Bi-for-La substitution.抄録全体を表示PDF形式でダウンロード (184K) -
山口 貴生, 吉川 信一, 金丸 文一1991 年 38 巻 8 号 p. 1005-1008
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーSubstitutions of Ln were investigated on both Ln1.85Ce0.15CuO4 (Ln=Pr, Nd, Sm, Eu) and La0.85Ln'Sr0.15CuO4 (Ln'=La, Pr, Nd, Sm, Eu, Gd) in relation to pressure effect of Tc. The Tc values decreased with an increasing atomic number of Ln3+ in both T' phase of Ln1.85Ce0.15CuO4 and T phase in La0.85Ln'Sr0.15CuO4. The decrease in Tc agrees with the negative pressure effect of T' phase but conflicts with the positive pressure dependence of Tc in T phase. Oxygen amount, which is crucial for superconducting transition temperature Tc, changed as well as lattice parameter with the Ln substitution.抄録全体を表示PDF形式でダウンロード (178K) -
池田 靖訓, タン・ミン・チョ , 広井 善二, 高野 幹夫, 坂東 尚周1991 年 38 巻 8 号 p. 1009-1012
発行日: 1991/11/25
公開日: 2010/07/12
ジャーナル フリーPhase equilibrium in the LaO1.5-BaO-CuO system at 1000°C in air has been studied mainly by powder X-ray diffraction. La2-xBaxCuOδ coexists with CuO, La4BaCu5Oδ, La3Ba3Cu6Oδ and La2-yBa1+yCu2Oδ (y=0.3) for 0≤x<0.05, 0.05<x<0.15, 0.15<x<0.23 and 0.23<x≤0.3, respectively. An anomalous sintering phenomenon was observed for a composition of x=0.125 of La2-xBaxCuOδ. We have newly found that the Ba-rich compositions of 0.125<x<0.3 were mixtures of two phases with x=0.125 and x=0.3 below 950°C.抄録全体を表示PDF形式でダウンロード (1578K) -
河村 雄司, 町田 信也, 重松 利彦, 中西 典彦, 池田 靖訓, 広井 善二, 高野 幹夫, 坂東 尚周, 武田 保雄, 山本 治1991 年 38 巻 8 号 p. 1013-1018
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーWe report the phase diagram for the pseudo-ternary system PrO1.83-CaO-CuO at 970°C in air. This temperature was chosen because partial melting occurs at 1000°C but not at this temperature. Two ternary phases were identified.One is a solid solution fomulated as Pr40-0.8xCaxCu60-0.2xOu (19<x<29). The XRD and electron diffraction patterns could be indexed by assuming orthorhombic structure of the NaCuO2 type basically: Pr20Ca25Cu55O (x=25) has a=10.693, b=2.825 and c=6.377 [Å] as an example.The structure is. however.modurated one-dimensionally and incommensurately the direction in the reciprocal space shifting from [010]toward [210] as x increases. The other phase, Pr4Ca10Cu24O ?? . has orthorhombic structure of the Sr14Cu24O ??, type with a=11.279, b=12.464 and c=3.940[Å]. This structure is also one-dimensionally and incomnensurately modulated along the direction of [010].抄録全体を表示PDF形式でダウンロード (2192K) -
志村 健一, 寺嶋 孝仁, 坂東 尚周, 松田 祐司, 小宮山 進1991 年 38 巻 8 号 p. 1019-1022
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーUltrathin films of YBa2Cu3O7(YBCO) were grown on nonsuperconducting PrBa2Cu3O7(PrBCO) buffer layers by reactive evaporation monitoring with RHEED oscillations. The one-unit-cell-thick layer of YBCO covered by a PrBCO layer exhibits a superconducting transition with the onset temperature at 70K. A reduction of the onset temperature is found to be mainly due to a decrease of the hole carriers. The covering PrBCO layer has been found to provide the underlying YBCO layer with the carriers.The resistive transition for one-unit-cell-thick YBCO layer was independent of the magnetic fields parallel to a-b plane.抄録全体を表示PDF形式でダウンロード (210K) -
佐藤 利文, 広井 善二, 寺嶋 孝仁, 志村 健一, 坂東 尚周1991 年 38 巻 8 号 p. 1023-1026
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーWe have examined the microstructures of Cu-oxide superconducting thin films by cross-sectional transmission electron microscopic(TEM) observation. The films were prepared by reactive evaporation method with RHEED oscillations monitoring. The cross-sectional TEM observation provided informations on the growth mechanism of 1:2:3 compounds and on the epitaxial relations between the films and substrates. Sharp interfaces between the thin film of 123 compound and substrate were confirmed.抄録全体を表示PDF形式でダウンロード (4236K) -
塚本 惠三, 下嶋 浩正, 石井 守, 山岸 千丈1991 年 38 巻 8 号 p. 1027-1030
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーThe Bi-Pb-Sr-Ca-Cu-O films were prepared on MgO crystal by rf magnetron sputtering using multi targets; Bi0.5Pb0.5Ox, CaCu0.75Ox and SrCu0.75Ox. The films were two-step-annealed to be crystallized. The primary annealing was done for 780°C×2 hours and the secondary annealing for 842°C×130 hours. Obtained films were patterned on a meander shape by photolithography method to increase the sensitivity in the magnetic field. The linewidth was 100μm and the space between lines was 50μm. The sensitivity in magnetic field for this small size film was 66.18mV/gauss. The result indicated that it is possibile to miniaturize the magnetic detector by the patterning of the superconducting film.抄録全体を表示PDF形式でダウンロード (1259K) -
安岡 宏, 高橋 亮吉, 西田 研一, 間崎 啓匡1991 年 38 巻 8 号 p. 1031-1034
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーTo examine the reliability of the measuring method of the critical current density Jc induced by a pulsed magnetic field, we measured Jc of high-Tc superconductors. The main advantages of this method are that it is not needed to use any electric contact, and that the measuring time is relatively short. Sintered and single-crystal YBa2Cu3Oy, sintered YBa2Cu4Oy and sintered Bi systems were prepared. Jc of YBa2Cu3Oy single-crystal thin films are about 106A/cm2 at liquid nitrogen temperature. This value agrees with the Jc measured by the four terminal method. The results of sintered samples also show a reasonable temperature dependence.抄録全体を表示PDF形式でダウンロード (253K) -
大野 悟, 奥山 秀男, 本間 一廣, 尾澤 正也1991 年 38 巻 8 号 p. 1035-1038
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーGreen powders with nominal composition of Bi4Sr3Ca3Cu6Oy doped with 0.5-3 mass%Ag were prepared by the impregnation technique using the aqueous solution of AgNO3. The sintering and superconducting properties of the green powders were studied by TG-DTA analysis, XRD, EPMA and magnetic susceptibility measurements.
TG-DTA measurements indicated that increase of Ag content in the green powders decreases melting points (partial and whole melting) of the powder, and increases the weight loss from 500 to 860°C. The formation of high-Tc (110 K) phase in the sintered specimen is enhanced significantly by Ag-doping of 1 mass% or more in the green powders.抄録全体を表示PDF形式でダウンロード (4886K) -
藤原 正志, 難波 徳郎, 高田 潤, 広井 善二, 池田 靖訓, 高野 幹夫1991 年 38 巻 8 号 p. 1039-1042
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーThe effects of Ba-addition to the high-Tc phase in the Bi-Pb-Sr-Ca-Cu system have been studied for the samples with a starting composition of Bi:Pb:Sr:Ba:Ca:Cu=0.9:0.2:1.0:x:1.0:1.6 heated at 850°C in air (x=0 to 0.10). Various amounts of BaCO3 were added to the high-Tc phase with a composition of Bi:Pb:Sr:Ca:Cu=0.9:0.2:1.0:1.0:1.6. Ba-addition raises Tc; Tc(R-0)=122K and Tc(R=0)=120K for the sample with x=0.05 heated at 850°C for 60h. XRD and ICP analyses indicate that the high-Tc phase contains Ba of x≤0.05 as a solid solution.抄録全体を表示PDF形式でダウンロード (205K) -
草野 圭弘, 山口 一裕, 福原 実, 土井 章, 高田 利夫, 藤原 正志, 高田 潤1991 年 38 巻 8 号 p. 1043-1047
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーIn order to study the effects of Ba-addition to the high-Tc phase in the Bi-Pb-Sr-Ca-Cu-O system, measurements of X-ray diffraction and DC resistance, SEM observations and EDX analysis were made for samples with compositions of Bi:Pb:Sr:Ca:Cu:Ba=0.9:0.2:1.0:1.0:1.6:x (x=0-0.10). Samples were prepared by mixing powders of the high-Tc phase and BaCO3 and heating at 835 to 855°C for 60h in air. The high-Tc phase was without other compounds obtained in samples with x=0.04 to 0.05 heated at 845 to 850°C for 60h. Dissolution of Ba into the high-Tc phase was confirmed by EDX analysis. Ba-addition increases the c-axis length of the high-Tc phase and Tc(R=0) up to 119K. The growth of the high-Tc phase was found to be accelerated by Ba-addition.抄録全体を表示PDF形式でダウンロード (3513K) -
矢田 節男, 池田 靖訓, 高田 潤, 伊藤 秀章, 山本 凉市, 高野 幹夫, 中 重治1991 年 38 巻 8 号 p. 1048-1052
発行日: 1991/11/25
公開日: 2009/12/04
ジャーナル フリーThe sintering behavior and superconducting properties of the high Tc phase in the Bi(Pb)-Sr-Ca-Cu-O system were investigated using the starting powder with a composition Bi1.8Pb0.4Sr2.0-Ca2.0Cu3.2Oy, which was added to by 0.10mol or 0.15mol of MgO, CaO, SrO and BaO each, then pressformed at 2000kg/cm2 or 5000kg/cm2 and sintered at 850°C or 860°C for 120hr. The influence of the CaO additive was examined in detail in the range of x=0.0-0.7 for Bi1.8Pb0.4Sr2.0Ca2.0+xCu3.2Oy. Bulk densities of 4.8-4.9g/cm2 were obtained in the oxide added systems that were press-formed at 5000kg/cm2 and sintered at 850°C, while Tc was nearly constant at 107-111K. Jc measured at 77K ex-ceeded 500A/cm for both the MgO and CaO added systems. With increasing additive content (x) the bulk density of the above CaO additive system decreased from 4.8 to 4.lg/cm2 at 850°C and from 4.7 to 4.3g/cm2 at 860°C. Tc(zero resistance) increased with increasing x, suggesting that the amount of the coexisting low Tc phase was decreased. The Jc(77K) value increased with x and attained a maximum of 1100A/cm2 at x=0.4 sintered at 850°C and at x=0.6 sintered at 860°C, 4-5 times higher than that of x=0.0.抄録全体を表示PDF形式でダウンロード (337K) -
山本 凉市, 矢田 節男, 伊藤 秀章, 間崎 啓匡, 高田 潤, 中 重治1991 年 38 巻 8 号 p. 1053-1057
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーThe effects of the additives of 0.005-0.3mol of CaCO3(CaO), SrO, CaF2 and SrF2 to 2mol of the "2223" phase on the sintering behavior and the superconducting properties were investigated. The "2223" phase had a composition of Bi1.8Pb0.4Sr2.0Ca2.0Cu3.2Oy. The typical sintering temperature was 850°C for the CaO- or SrO- added system and was a little lower -840°C, for the CaF2- or SrF2- added system, when the sintering was conducted for 120hr using specimens press-formed at 5000 kg/cm2. The bulk density of the 0.3mol CaO-added specimen sintered at 850°C was 4.8g/cm3, and the critical current density, Jc at 77K, was -103A/cm2, better than that of the SrO-added specimen. The fluoride-added specimens had higher densities 5.3-5.5g/cm3, while the Jc was not increased. Tc was not influenced by the additives and remained at -110K.抄録全体を表示PDF形式でダウンロード (353K) -
真島 一彦, 坂本 俊悟, 勝山 茂, 永井 宏1991 年 38 巻 8 号 p. 1058-1061
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーThe high temperature electrical resistivity of Bi2Sr2CaCu2Oy superconductor was studied in H2 of 0.9atm or 2.Oatm. Sudden increase of electrical resistivity was obsereved above 200°C during the heating process both in 0.9atm and 2.0atm H2 gas, and it was confirmed that this phenomenon well corresponded to the distinct weight loss observed above about 200°C. An increase of Tc(on) was recognized for specimens heat-treated at 100°Cor 150°C in H2 gas. For example, the Tc(on) of the specimen heat-treated at 150°C in H2 gas of 2.0atm was 93K which is higher by about 13K than that of the as-sintered specimen.抄録全体を表示PDF形式でダウンロード (259K) -
堀田 勝喜, 鈴木 敏正, 廣瀬 治男, 篤籠 秀和, 遠藤 和弘1991 年 38 巻 8 号 p. 1062-1065
発行日: 1991/11/25
公開日: 2009/12/04
ジャーナル フリーWe reported on the effect of water or organic solvents on Bi-Pb-Sr-Ca-Cu-O superconductor in the preceding report. This article reports the changes of superconducting properties of samples soaked in water-included solvents as a parameter of moisture and soaking time. Organic solvents used in this experiment are ethyl alcohol, methyl alcohol, acetone and toluene. At all solvents except toluene, the rate of drop of Tc(end) increased and that of Jc reduced with increasing content of water. In the case of ethyl alcohol, we obtained that Jc's value showed the increasing tendency. For the toluene soaking, the value of Tc(end) and Jc did not change since the water could not be mix with toluene.抄録全体を表示PDF形式でダウンロード (189K) -
間崎 啓匡, 垣花 真人, 安岡 宏1991 年 38 巻 8 号 p. 1066-1070
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーSuperconducting Bi-Sr-Ca-Y-Cu-O ceramics have been synthe-sized by the polymerized complex method at the Bi2Sr2Ca1-xYxCu2Oy (0 ≤ x ≤ 0.4) compositions, and the dependence of the superconducting transition on the hole concentration was studied. The onset temperature of the superconducting transition Tc(onset) was carefully measured in terms of complex susceptibility. The onset temperature is enhanced as x increases up to x = 0.1 and then decreases as x further increases. Wet chemical analyses were carried out to determine the average charges of Bi and Cu ions. To interpret the results, we propose that the mixed valence of Bi+5 and Bi+3 acts as a charge reservoir for the Cu02 planes.抄録全体を表示PDF形式でダウンロード (256K) -
石川 雄一, 洞田 勇輝, 古澤 秀二, 宮島 英紀1991 年 38 巻 8 号 p. 1071-1074
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーOne of the applications of high-Tc oxide superconductor is magnetic shielding. For example, it is very important to shield very weak fields produced in the human body from the geomagnetic field or fields generated by the electric instruments in order to detect precisely them. The purpose of this study is to investigate the relation between the shielding efficiency and the superconducting properties. The cylinders made up from Bi2Sr2Ca2Cu3Ox high-Tc superconductors with different critical currents and magnetizations were prepared by changing the sintering condition. The shielding efficiency in the cylinder was measured as functions of the shape factor of L/D of the cylinder and the internal position of the cylinder, where L and D are the lenght and inner diameter of the cylinder, respectively. The shielding efficiency, defined by the ratio of the transverse and applied fields, was logarithmically dependent on the shape factor and increased with the critical current and volume fraction of the superconducting component which is in proportion to the gradient of the initial magnetization curve. The efficiency, however, was independent of the magnitude of the magnetization and the frequency of the external AC magnetic field.抄録全体を表示PDF形式でダウンロード (174K) -
塚本 惠三, 石井 守, 下嶋 浩正, 山岸 千丈, 高田 雅介, 山下 努1991 年 38 巻 8 号 p. 1075-1078
発行日: 1991/11/25
公開日: 2009/12/04
ジャーナル フリーBi(Pb)-Sr-Ca-Cu-O superconducting tubes with different wall thicknesses were fabricated to examine the wall thickness dependence of the magnetic shielding property. The external magnetic flux density, at which the flux starts to penetrate into the tube center, is referred as the shielding magnetic flux density. The shielding magnetic flux density was increased logarithmic with increasing the wall thickness. The wall thickness dependence of the shielding magnetic flux density was calculated using the critical state model in consideration of the magnetic field dependence of the critical current density. This calculated dependence agreed with the experimental one approximately.抄録全体を表示PDF形式でダウンロード (206K) -
佐藤 隆士, 小松 高行, 松下 和正1991 年 38 巻 8 号 p. 1079-1082
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーWe prepared superconducting Bi2Sr2CaCu2Ox, glass-ceramics by the melt-quenching method (glass-ceramic route) and examined the effect of annealing condition on their microstructures. In the sample annealed at 820°C for 24h (one step), the surface (<500 u m) had a homogeneous structure, but the large grain growth and the porous structure were observed in the inside of sample. In the sample annealed first at 700°C for 24h and then at 820°C 24h (two step), the homogeneous and dense structure without any pore was observed. The relation between the difference of microstructures and the formation mechanism of superconducting crystals was clarified. It was found that a liquid phase was created in the inside of bulk during the continuous heating to around 800°C and a rapid grain growth of superconducting crystals in the inside was due to the formation of this liquid phase.抄録全体を表示PDF形式でダウンロード (5505K) -
原田 幸明, 皆川 和己, 奥山 秀男, 本間 一広1991 年 38 巻 8 号 p. 1083-1088
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーPhase change of rapidly solidified Bi-Sr-Ca-Cu-O amorphous ceramics was investigated. Crystalization took place at 500°C, following shrinkage above glass transition. First cystalized phase was 2.4nm phase. While 3.Onm phase appeared at about 700°C, 2.4nm phase was still dominant below 800°C. When 2.4nm phase disappeared, smaller particles and fibre began to merge with coarser particles. Above 830°C 3.Onm phase were dominant, but phase separation took place in an atomized particle. Eventually long bill-like (Ca, Cu)Ox crystal grew out from each atomized particle, and Bi-rich part was simultaneously formed, which gave lower transition-melting temperature than that of mixed and calcined powders.抄録全体を表示PDF形式でダウンロード (3434K) -
西田 俊彦, 島野 晋, 浦部 和順1991 年 38 巻 8 号 p. 1089-1093
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーBi2Sr2CaCu2Ox ceramic powder prepared by a solid state reaction was encapsulated in Ag can with a dimensions of 32φ(O.D.)-20φ(I.D.)×55 ?? mm. The bullet (can containing ceramic powder) was
preheated at 840°C for about 10 min and was extruded rapidly to avoid excessive heat loss.
Many kinds of disordered structure were observed in the hot-extruded ceramics by TEM. They were mechanically disordered grain boundaries, microfractured grains, and amorphous regions. The disordered structure regions changed, however, to polycrystals composed of small grains without grain boundary second phase after annealing at 800°C for 1 hr. The densification mechanism of the Bi-superconducting ceramic powder during the hot-extrusion processing was discussed by considering the microstructural change.抄録全体を表示PDF形式でダウンロード (5238K) -
藤原 正市, 日高 久夫, 小川 義光, 吉澤 秀二1991 年 38 巻 8 号 p. 1094-1097
発行日: 1991/11/25
公開日: 2009/05/22
ジャーナル フリーHigh Tc superconductive thick films of YBCO system were prepared by the spray-pyrolysis process using toluene solution of metal naphthenates as starting materials. After spraying the mixed solutions of yttrium, barium and copper naphthenates on the yttria-stabilized zirconia (YSZ) substrates and then preheating them at 500°C for 10min, we sintered them at 950-1070°C for 10min. They were finally annealed at 600°C for 10hr in oxygen gas. The specimens which were sintered in the partially melted state above 1010°C showed the Tc, zero at 90K. The critical current density (Jc) of 500A/cm2 at 77K was obtained in thespecimen sintered at 1050°C for 10min.抄録全体を表示PDF形式でダウンロード (1408K)
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