研究者詳細 - 生田　博志

論文 - 生田　博志

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The Effects of Process Conditions on YBa_2_Cu_3_O_7-x_ Films by Metalorganic Deposition (MOD) Method using Trifluoroacetates 査読有り

T. Araki, K. Yamagiwa, Y. Takahashi, S. B. Kim, I. Hirabayashi, H. Hiei, U. Mizutani, H. Ikuta

Ceramic Transactions 112 巻頁： 293-298 2001年

Preparation of YBa_2_Cu_3_O_7-y_ Thin Films by Chemical Solution Deposition Method on CeO_2_ and Y_2_O_3_ Buffer Layers 査読有り

H. Hiei, U. Mizutani, H. Ikuta, K. Yamagiwa, Y. Takahashi, S. B. Kim, I. Hirabayashi, J. Shibata, T. Hirayama

Ceramic Transactions 112 巻頁： 287-292 2001年

First-order vortex phase transition in Bi_2_Sr_2_CaCu_2_O_y_ single crystals with different carrier concentrations studied by resistivity measurements 査読有り

S. Watauchi, H. Ikuta, H. Kobayashi, J. Shimoyama, and K. Kishio

Physical Review B 64 巻頁： 064520 2001年

記述言語：英語掲載種別：研究論文（学術雑誌）

The first-order vortex phase transition (FOT) in Bi_2_Sr_2_CaCu_2_O_y_ single crystals with different carrier concentrations was investigated by measuring the in-plane resistivity (r_ab_) under magnetic field applied parallel to the crystallographic c-axis direction. With decreasing the temperature, r_ab_ dropped sharply at the FOT temperature when the applied field was smaller than the second-peak-field (H_pk_) that was determined by measuring the magnetic hysteresis curves at 25-30 K, while no such an abrupt change was observed when the applied field was larger than H_pk_. The temperature range where the FOT was observed was approximately between 0.6 to 0.95 in the scale of the reduced temperature (t=T/T_c_) for all crystals. The first-order transition field (H_t_) as a function of t shifted to higher fields as the carrier concentration of the crystal increased, which can be well scaled by the electromagnetic anisotropy factor (g). Irrespective of the carrier doping level, the temperature dependence of H_t_ is experimentally expressed better by H_t_=a(t^-1^-t), rather than the functional form proposed by the conventional decoupling theory of vortex lattice (H_t_=a(t^-1^-1)). This experimental formula can be accounted for by the decoupling theory if the temperature dependence of the magnetic penetration depth is assumed to scale as l^-2^=a(1-t^2^).

Non-cuprate thin films as candidates of seed layer for liquid phase epitaxy process 査読有り

T. Miura, Y. Yamada, T. Suga, D. Huang, S. B. Kim, T. Maeda, I. Hirabayashi, H. Ikuta, and U. Mizutani

Physica C 357-360 巻頁： 983 2001年

YBCO Thin Films on Multilayers Prepared by All-Chemical Solution Deposition Processing 査読有り

H. Hiei, K. Yamagiwa, Y. Takahashi, S. B. Kim, Y. Yamada, J. Shibata, T. Hirayama, H. Ikuta, I. Hirabayashi, and U. Mizutani

Physica C 357-360 巻頁： 942 2001年

記述言語：英語掲載種別：研究論文（学術雑誌）

The chemical solution deposition (CSD) technique has been applied to prepare both YBa_2_Cu_3_O_7-d_ (YBCO) and buffer layers on a YSZ substrate. Y_2_O_3_ and CeO_2_ were employed as the buffer layers, and it was confirmed that they grew epitaxially by the CSD method. Cross-sectional TEM observations revealed that Y_2_O_3_ grew up to the top of the film. Furthermore, the YBCO film on the Y_2_O_3_ or CeO_2_/Y_2_O_3_ layers were c-axis aligned and showed a good in-plane alignment. The transition temperature and the critical current density of the YBCO/Y_2_O_3_/YSZ multilayer were 89 K and 4.0x10^4^ A/cm^2^ at 77 K, 0T, respectively.

Melt-Processing and the Performance as a Superconducting Permanent Magnet of RE-Ba-Cu-O/Ag (RE=Sm, Nd) 査読有り

H. Ikuta, Y. Yanagi, M. Yoshikawa, Y. Itoh, T. Oka, and U. Mizutani

Physica C 357-360 巻頁： 837 2001年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The amount of magnetic flux that a melt-processed bulk-superconductor can trap has drastically increased recently by the successful synthesis of single domain RE-Ba-Cu-O (RE=Sm, Nd) samples with the addition of Ag. As a result of this progress in processing, it became increasingly important to develop an efficient and practical magnetization technique to extract the potential of the material in applications that use melt-grown superconductors as quasi-permanent magnets. We review our recent works on the melt-growth technique as well as the pulse field magnetization studies. Using these techniques, we have constructed a magnetic field generator, the performance of which is evaluated in this study.

Improvement of the Microstructure of Melt-Processed Sm-Based Superconductors 査読有り

K. Tazoe, H. Ikuta, M. Yoshikawa, Y. Yanagi, Y. Itoh, T. Oka, and U. Mizutani

Physica C 357-360 巻頁： 807 2001年

記述言語：英語掲載種別：研究論文（学術雑誌）

We report on the effect of the atmosphere during the decomposition of the precursors of Sm-Ba-Cu-O bulk superconductors. It was found that the formation of voids was greatly suppressed by two methods, melting in an oxygen gas atmosphere or in vacuum. For both meth-ods, the atmosphere during crystallization was switched to an Ar-gas flowing one. The samples prepared by these methods exhibited high superconducting transition temperatures with sharp transition widths. However, the zero-field critical current density was lower than that of the reference sample, which was prepared by decomposing the precursor in an Ar-gas flowing atmosphere.

Pulsed Field Magnetization of Melt-Processed Sm-Ba-Cu-O 査読有り

H. Ishihara, H. Ikuta, Y. Itoh, Y. Yanagi, M. Yoshikawa, T. Oka, and U. Mizutani

Physica C 357-360 巻頁： 763 2001年

記述言語：英語掲載種別：研究論文（学術雑誌）

We studied the dynamical motion of flux lines in a melt-processed Sm-Ba-Cu-O bulk-superconductor driven by a magnetic pulse using seven small Hall sensors. The time dependence of the magnetic flux density was measured on a crystalline facet line and on an inter-facet region. It was observed that flux lines move faster along the inter-facet region, and a larger amount of magnetic flux is trapped in the facet regions after the application of a magnetic pulse. A comparatively larger pinning effect in the facet region is considered to be responsible for these observations.

Effect of Zn Substitution on the One-Dimensional Metallic Behavior of PrBa_2_Cu_4_O_8_ 査読有り

K. Nakada, H. Ikuta, S. Horii, H. Nozaki, I. Hirabayashi, and U. Mizutani

Physica C 357-360 巻頁： 186 2001年

記述言語：英語掲載種別：研究論文（学術雑誌）

We have grown PrBa_2_(Cu_1-x_Zn_x_)_4_O_8_ single crystals with nominal compositions of x=0, 0.05, 0.10, and 0.15, and measured the resistivity along a- and b-axis directions. For the Zn-free sample, the conduction along the b-axis direction was highly metallic, which persisted up to the x=0.15 sample although the doping of Zn increased the resistivity. On the other hand, the a-axis resistivity of the Zn-free crystal exhibited a peak around 130 K, which is attributable to a switching of the dominant conduction path from the Cu-O chain site at low temperature to the CuO_2_ plane at high temperature. With Zn doping, the peak moves to lower temperature and the resistivity extrapolated to T=0 increases, indicating that Zn doping suppresses the coherent conduction across Cu-O chains.

Thermoelectric Properties of (Ca,Sr,Bi)_2_Co_2_O_5_ Whiskers 査読有り

R. Funahashi, I. Matsubara, H. Ikuta, T. Takeuchi, and U. Mizutani

Materials Transactions 42 巻頁： 956 2001年

Melt-Processed RE-Ba-Cu-O (RE=Sm, Nd) Superconductors for Quasi-Permanent Magnets 査読有り

H. Ikuta, T. Hosokawa, H. Ishihara, M. Yoshikawa, Y. Yanagi, Y. Itoh, T. Oka, and U. Mizutani

IEEE Trans. Appl. Superconduct. 11 巻頁： 3716 2001年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The microstructures of melt-processed NdBCO/Ag samples were investigated. A rather homogeneous distribution of Nd422 particles was found, which can be attributed to the fast growing speed of NdBCO and the large size of Nd422 particles. The dispersion of Ag depended on the content of Ag_2_O, and the phase relation of the NdBCO/Ag system is discussed. We also studied the pulsed field magnetization technique, and found that the amount of magnetic fluxes trapped by SmBCO significantly increased by sandwiching the sample with ferromagnetic yokes and repeatedly applying magnetic pulses with decreasing the amplitude.

Construction of a 2-5 T class superconducting magnetic fieldgenerator with use of an Sm123 bulk superconductor and its application to high-magnetic field demanding devices 査読有り

T. Oka, Y. Itoh, Y. Yanagi, M. Yoshikawa, H. Ikuta, and U. Mizutani

Physica C 335 巻頁： 101 2000年

Mechanical Properties of Sm-Ba-Cu-O/Ag Bulk Superconductors 査読有り

N. Sakai, A. Mase, H. Ikuta, S-J. Seo, U. Mizutani, and M. Murakami

Supercond. Sci. Technol. 13 巻頁： 770 2000年

Application of the Superconducting Permanent Magnets Driven by Static and Pulsed Magnetic Fields 査読有り

U. Mizutani, H. Ikuta, T. Hosokawa, H. Ishihara, K. Tazoe, T. Oka, Y. Itoh, Y. Yanagi, and M. Yoshikawa

Supercond. Sci. Technol. 13 巻頁： 836 2000年

Synthesis of c-axis-oriented Sm123 superconductors and their performance as superconducting permanent magnets 査読有り

U. Mizutani, A. Mase, K. Tazoe, H. Ikuta, T. Oka, Y. Itoh, Y. Yanagi, and M. Yoshikawa

Physica C 335 巻頁： 92 2000年

Preparation of bi-axially aligned YBa_2_Cu_3_O_7-d_ film on CeO_2_ buffered MgO by chemical solution deposition 査読有り

K. Yamagiwa, H. Hiei, Y. Takahashi, S. B. Kim, K. Matsumoto, H. Ikuta, U. Mizutani, and I. Hirabayashi

Physica C 334 巻頁： 301 2000年

Trapped Field Distribution on Sm-Ba-Cu-O Bulk Superconductor by Pulsed-Field Magnetization 査読有り

Y. Yanagi, Y. Itoh, M. Yoshikawa, T. Oka, T. Hosokawa, H. Ishihara, H. Ikuta, and U. Mizutani

Advances in Superconductivity 12 巻頁： 470 2000年

Synthesis of c-axis Oriented RE-Ba-Cu-O (RE=Sm and Nd) Superconductors and Performance of Superconducting Permanenet Magnets Activated by Pulsed Fields 査読有り

U. Mizutani, H. Ikuta, T. Hosokawa, H. Ishihara, T. Oka, Y. Itoh, Y. Yanagi, and M. Yoshikawa

Advances in Superconductivity 12 巻頁： 431 2000年

Preparation of NdBa_2_Cu_3_O_x_ Thin Films and Their Superconducting Properties in Magnetic Fields 査読有り

Y. Ichino, K. Matsumoto, Y. Takahashi, S. B. Kim, I. H. H. Ikuta, and U. Mizutani

Advances in Superconductivity 12 巻頁： 879 2000年

Influence of Carbon on YBa_2_Cu_3_O_6+x_ Single Crystalline Thick Film 査読有り

T. Miura, Y. Yamada, Y. Koike, H. Ikuta, I. Hirabayashi, and U. Mizutani

Advances in Superconductivity 12 巻頁： 607 2000年

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