Faculty Profiles - NANBA Tokuro

Chemical and Mechanical Stability of the High-Tc Phase in the Bi-Pb-Sr-Ca-Cu-O System. (I). Effects of Heat Treatment of Crushed Powder of the High-Tc Phase.:Effects of Heat Treatment of Crushed Powder of the High-Tc Phase Reviewed

Other Link： https://jlc.jst.go.jp/DN/JALC/00023714045?from=CiNii

Preparation of Fe3O4 Single-crystalline Films by Reactive Evaporation Method. Reviewed

Fujii Tatsuo, Sakamoto Masakatsu, Asano Mitsuhiro, Nanba Tokuro, Osaka Akiyoshi, Miura Yoshinari, Takada Jun, Shimura Ken-ichi, Terashima Takahito, Bando Yoshichika

J. Jpn. Soc. Powder Powder Metallurgy 39 ( 11 ) 981 - 984 1992.11

Language：Japanese Publisher：Japan Society of Powder and Powder Metallurgy

(111)- and (100)-oriented Fe₃O₄ films were epitaxially formed on a-A1₂O₃(0001) and MgO(100) single-crystalline substrates, respectively, by reactive evaporation method. The formation ranges of the epitaxial Fe₃0₄ films were determined as a function of substrate temperature, oxygen partial pressure, and a deposition rate. Their crystalline qualities were examined by various methods such as X-ray diffraction, RHEED and resistivity mesurements. A lattice mismatch of about 0.3% between Fe₃O₄ and MgO was very small. Then the film deposited on MgO seemed to have a good crystallinity and a smooth surface. Moreover the Verwey transition was clearly detected by a resistivity mesurement at about 110K. The transition temperature was nearly consistent with that of the bulk, indicating a good stoichiornetry of the sample film.

DOI： 10.2497/jjspm.39.981

Other Link： https://jlc.jst.go.jp/DN/JALC/00018090598?from=CiNii

Takada Jun, Hosotani Katsunori, Fujiwara Masashi, Kusano Yoshihiro, Nanba Tokuro, Ikeda Yasunori, Takano Mikio

J. Jpn. Soc. Powder Powder Metallurgy 39 ( 9 ) 779 - 782 1992.9

Language：Japanese Publisher：Japan Society of Powder and Powder Metallurgy

Chemical and mechanical stability of the high-Tc phase has been studied for the samples of Bi_0.9Pb_0.2Sr_1.0Ca_1.0Cu_1.6O_x. Mechanical grinding converts the high-Tc phase into a nonsuperconducting amorphous phase. The ground high-Tc phase is not stabilized on annealing at lower temperatures below 820°C. Annealing at lower temperature leads to precipitation of some impurity phases and the low-Tc phase which depends on annealing temperature and time. The high-Tc phase is recovered by annealing at 850°C. The lattice parameters a and c of the high-Tc phase annealed at 850°C are longer than those below 820°C.

DOI： 10.2497/jjspm.39.779

Other Link： https://jlc.jst.go.jp/DN/JALC/00016828827?from=CiNii

Effect of Li Addition to the Low-Tc Phase in the Bi-Sr-Ca-Cu-O System. (I). Reviewed

Takada Jun, Endo Kazuyo, Kusano Yoshihiro, Nanba Tokuro

J. Jpn. Soc. Powder Powder Metallurgy 39 ( 9 ) 763 - 766 1992.9

Language：Japanese Publisher：Japan Society of Powder and Powder Metallurgy

The effect of Li-addition to the low-Tc phase in Bi-Sr-Ca-Cu-O system have been studied for the samples with nominal compositions of Bi:Sr:Ca:Cu:Li=2:1.5:1.5:2-x:x heated at 720 to 845°C for 12 to 24h in air (x=0 to 0.8). The Li-addition promotes the formation of the low-Tc phase. Single phase of the low-Tc phase was obtained for the sample with x=0.2 to 0.4 more easily than the sample with x=0. The lattice constant c of the low-Tc phase increases as the Li content increases. As the heating period becomes longer, the amount of Li content in the low-Tc phase decreases.

DOI： 10.2497/jjspm.39.763

Preparation and Characterization of Ti(2)O(3) Films Deposited on Sapphire Substrate by Activated Reactive Evaporation Method

Other Link： https://jlc.jst.go.jp/DN/JALC/00016828780?from=CiNii

Fujii Tatsuo, Sakata Naoki, Nanba Tokuro, Osaka Akiyoshi, Miura Yoshinari, Takada Jun

Memoirs of the Faculty of Engineering, Okayama University 26 ( 2 ) 69 - 75 1992.3

Effect of Ba Addition to the High-Tc Phase in the Bi-Pb-Sr-Ca-Cu-O System(V) Reviewed

Yoshihiro Kusano, Kazuhiro Yamaguchi, Minoru Fukuhara, Akira Doi, Toshio Takada, Masashi Fujiwara, Jun Takada

Jpn. J. Powder Powder Metall. 39 ( 5 ) 374 - 377 1992

Language：Japanese Publisher：Japan Society of Powder and Powder Metallurgy

The effects of cooling condition and Ba addition time on Tc of high-Tc phase in the Bi-Pb-Sr-Ca-Cu-O system were studied. X-ray diffraction and DC resistance measurements were carried out to observe phase identification and Tc values for a series of samples with compositions of Bi:Pb:Sr:Ba:Ca:Cu=0.9:0.2:1.0:X:1.0:1.6(X=0-0.05). When a mixture of BaCO₃ and synthesized high-Tc phase was heated at 850°C for 60h in air, only a solid solution of high-Tc phase was formed in a quenched sample. However, in a sample cooled down slowly, Bi₃(Sr, Ba)₄Ca₃O_z was found as an impurity phase in addition to the solid solution of high-Tc phase. Mixtures of BaCO₃ (X=0.04) and the rest of metal oxides or metal carbonates were heated at 845°C 96h in air. Bi₃(Sr, Ba)₄Ca₃O_z was also found in addition to the high-Tc phase in a quenched sample. When BaCO₃ was added to the synthesized high-Tc phase, Tc(R=0) was 119K for the heated samples. When BaCO₃ was added in starting materials, Tc decreased to 110K due to the formation of Bi₃(Sr, Ba)₄Ca₃O_Z.

DOI： 10.2497/jjspm.39.374

Effect of Ba-addition to the High-Tc Phase in the Bi-Pb-Sr-Ca-Cu-O System. (VI)

Other Link： https://jlc.jst.go.jp/DN/JALC/00015023872?from=CiNii

Preparation of Fe3O4/MgO Artificial Superlattices by Activated Reactive Evaporation Method Reviewed

Masakatsu Sakamoto, Mitsuhiro Asano, Tatsuo Fujii, Tokuro Nanba, Akiyoshi Osaka, Yoshinari Miura, Jun Takada

journal of the japan society of powder and powder metallurgy 39 ( 11 ) 985 - 988 1992

Yoshihiro Kusano, Tokuro Nanba, Jun Takada, Naoya Kobayashi, Kazuhiro Yamaguchi, Minoru Fukuhara, Akira Doi, Toshio Takada, Yasunori Ikeda, Mikio Takano, Hiromasa Mazaki

Journal of the Japan Society of Powder and Powder Metallurgy 39 ( 9 ) 771 - 774 1992

Language：Japanese Publisher：Japan Society of Powder and Powder Metallurgy

The effects of Ba addition and grinding time on Tc of the high-Tc phase in the Bi-Pb-Sr-Ca-Cu-O system have been studied. Samples with compositions of Bi:Pb:Sr:Ba:Ca:Cu=0.9:0.2:1.0:X:1.0:1.6(X=0-0.05) were prepared by grinding the high-Tc phase and BaCO₃ powders for various periods (20 to 120min). The high-Tc phase degraded with grinding time. In samples of a composition of X=0.05 heated at 845≥C for 60h in air, a small amount of the low-Tc phase and Bi₃(Sr, Ba)₄Ca₃O_z besides the high-Tc phase were formed. The heating led to the grain growth of the high- Tc phase with increasing grinding time. However, Tc(R=0) was decreased due to the formation of the low-Tc phase and Bi₃(Sr, Ba)₄Ca₃O_z.<BR>In a sample with X=0.05 heated at 850°C for 60h in air, only a solid solution of the high-Tc phase was formed. Tc(R=O)=125K was attained in this sample. The Meissner diamagnetic response at 125K was confirmed by SQUID, but the volume fraction of the 125K phase was estimated below 1%.

DOI： 10.2497/jjspm.39.771

Other Link： https://jlc.jst.go.jp/DN/JALC/00016828803?from=CiNii

Effect of Ba-addition to the High-Tc Phase in the Bi-Pb-Sr-Ca-Cu-O system Reviewed

Masashi Fujiwara, Tokuro Nanba, Jun Takada, Zenji Hiroi, Yasunori Ikeda, Mikio Takano

Journal of the Japan Society of Powder and Powder Metallurgy 38 ( 8 ) 1039 - 1042 1991

Language：English

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. © 1991, Japan Society of Powder and Powder Metallurgy. All rights reserved.

DOI： 10.2497/jjspm.38.1039

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