1991 Fiscal Year Annual Research Report

酸化物超伝導体の磁束ピンニングに関する研究

Research Project

Project/Area Number	03210203
Research Institution	Tohoku University
Principal Investigator	渡辺和雄東北大学, 金属材料研究所, 助教授 (30143027)
Co-Investigator(Kenkyū-buntansha)	淡路智東北大学, 金属材料研究所, 助手 (10222770)
Keywords	酸化物高温超伝導体 / 臨界電流密度 / 磁束ピンニング
Research Abstract	高T_c酸化物超伝導体の応用において最も重要なパラメ-タである臨界電流密度に関する研究を実施してきた。酸化物超伝導体の磁束ピンニングを解明するため,臨界電流の決定方法、組織とB_<c2>,J_cの関係、磁束ピンニングを検討した。以下に本年度の成果をまとめる。 (1)QMG法Y_1Ba_2Cu_3O_7バルクの磁化測定をB〓C,B⊥Cで23Tまで行った。4.2Kでは非常に多くの磁束ジャンプが出現した。断熱安定性の理論を用いると、磁束ジャンプを抑えるためには数10μmの極細化が必要である結果が得られた。さらに、強磁場までの磁化測定からは、QMG法バルクには弱結合性が存在していることが分った。 (2)CVD法とスパッタ法Y_1Ba_2Cu_3O_7膜におけるJ_cの角度依存性を比較検討した。組織は非常に異っているにもかかわらず、両者とも77Kでの強磁場中のJ_c特性が優れている。B_<c2>,J_cの角度依存性は、いずれも同じ磁束ピンニングのスケ-ル則とB_<c2>の角度依存性によって説明できた。 (3)磁束ピンニング力に対する磁束クリ-プの影響がどのようなものになるのかを検討した。高温領域では磁束クリ-プが顕著であるが、Kramer型のF_p曲線になる報告が多い。実測したJ_c値は磁束クリ-プの影響を受けていると考えて、F_p曲線にその影響による補正を行った。補正されたF_p曲線と実測されたKramer型曲線とを比較することで、磁束クリ-プが影響していないF_p曲線としてF_pαb^<1/2>(1-b)^<3/2>を得ることができた。これは、従来型のNbT〓線材にも観測されるF_p曲線であり、磁束ピンニング機構を考える上でピンニングの加算問題を検討しなければならないものと判断される。

Research Products
(19 results)

All Other

All Publications (19 results)

[Publications] K.Watanabe: "Angular Dependence of the Upper Critical Field and the Critical Current Density for Y_1Ba_2Cu_3O_<7-δ>Films" J.Appl.Phys.69. 1543-1546 (1991)
[Publications] S.Matsuno: "Critical Current Properties under High Magnetic Fields up to 30 T for YーBaーCuーO Films by MOCVD" IEEE Trans.Magn.27. 1398-1401 (1991)
[Publications] K.Watanabe: "Angular Dependence of the Trasport Critical Current Density of CVD YBaCuO Film" Superconductivity and Applications. 398-404 (1991)
[Publications] K.Watanabe: "Flux Pinning in CVD Processed YBaCuO Film" Advances in Superconductivity. 473-478 (1991)
[Publications] K.Watanabe: "Critical Current and Flux Pinning in Y_1Ba_2Cu_3O_<7-δ>Films Prepared by Chemical Vapor Deposition" High‐Temperature Superconductors. 192-198 (1991)
[Publications] K.Watanabe: "Magnetic Instability in HighーJ_c Y_1Ba_2Cu_3O_7 Prepared by QuenchーMeltーGrowth Process" Jpn.J.Appl.Phys.30. L1638-L1640 (1991)
[Publications] S.Awaji: "Angular Dependence of J_c and B_<c2> in the CVDーYBa_2Cu_3O_<7-δ>Films" Physica. C185ー189. 2199-2200 (1991)
[Publications] K.Yamafuju: "On the Difference of Pinning Potentials for Thermally Activated Flux Creep Estimated by Resistive and Magnetization Measurements in High T_c Superconducting Films" Physica. C185ー189. 2285-2286 (1991)
[Publications] N.Kobayashi: "Flux Creep in YBa_2Cu_3O_7 Films" Physica. C185ー189. 2353-2354 (1991)
[Publications] M.Matsukawa: "Critical Current Density and Dynamic Stability of HighーT_c Oxide Superconductor" Physica. C185ー189. 2477-2478 (1991)
[Publications] K.Watanabe: "CVD Route for High J_c Superconductors" Studies of High Temperature Superconductors. (1990)
[Publications] K.Noto: "High T_c Oxides" Handbook of Metallic CompositesーComposite Superconductorsー. (1991)
[Publications] K.Watanabe: "Polycrystalline Y_1Ba_2Cu_3O_<7-δ> Films Prepared by CVD Method" Proc.ICMC 91,Huntsville.
[Publications] K.Watanabe: "Magnetization Hysteresis in High Fields for QuenchーMeltーGrowth Processed Y_1Ba_2Cu_3O_7" Supercond.Sci.Technol.5. S288-291 (1992)
[Publications] K.Watanabe: "Critical Current Density and Its Related Problems in CVDーY_1Ba_2Cu_3O_7" Proc.2nd Tokai University Int.Conf.on Superconductivity,Honolulu(1991).
[Publications] K.Watanabe: "Anisotropy and Dimensional Characteristics in CVD Route Y_1Ba_2Cu_3O_<7-δ>" HighーTemperature Superconductors.
[Publications] S.Awaji: "Comparative Study of Critical Current Densities between Sputtered and CVD Processed YBa_2Cu_3O_<7-δ> Films" Proc.7th USーJapan WorkshoP on High Field Superconducting Materials,Wires and Conductors and Standard Procedures for HTSC Wires Testing,Fukuoka. 220-224 (1991)
[Publications] N.Kobayashi: "Anisotropic Behavior of J_c and Pinning Mechanism in HighーJ_c CVDーYBCO Films" Proc.7th USーJapan Workshop on High Field Superconducting Materials,Wires and Conductors and Standard Procedures for HTSC Wires Testing,Fukuoka. 196-201 (1991)
[Publications] N.Kobayashi: "Flux Creep and Pinning in highーJ_c YBCO Films" Proc.4th USーJapan Workshop on HTSC,Gaithersburg.

1991 Fiscal Year Annual Research Report

酸化物超伝導体の磁束ピンニングに関する研究

Principal Investigator

渡辺 和雄 東北大学, 金属材料研究所, 助教授 (30143027)

Research Products

[Publications] K.Watanabe: "Angular Dependence of the Upper Critical Field and the Critical Current Density for Y_1Ba_2Cu_3O_<7-δ>Films" J.Appl.Phys.69. 1543-1546 (1991)

[Publications] S.Matsuno: "Critical Current Properties under High Magnetic Fields up to 30 T for YーBaーCuーO Films by MOCVD" IEEE Trans.Magn.27. 1398-1401 (1991)

[Publications] K.Watanabe: "Angular Dependence of the Trasport Critical Current Density of CVD YBaCuO Film" Superconductivity and Applications. 398-404 (1991)

[Publications] K.Watanabe: "Flux Pinning in CVD Processed YBaCuO Film" Advances in Superconductivity. 473-478 (1991)

[Publications] K.Watanabe: "Critical Current and Flux Pinning in Y_1Ba_2Cu_3O_<7-δ>Films Prepared by Chemical Vapor Deposition" High‐Temperature Superconductors. 192-198 (1991)

[Publications] K.Watanabe: "Magnetic Instability in HighーJ_c Y_1Ba_2Cu_3O_7 Prepared by QuenchーMeltーGrowth Process" Jpn.J.Appl.Phys.30. L1638-L1640 (1991)

[Publications] S.Awaji: "Angular Dependence of J_c and B_<c2> in the CVDーYBa_2Cu_3O_<7-δ>Films" Physica. C185ー189. 2199-2200 (1991)

[Publications] K.Yamafuju: "On the Difference of Pinning Potentials for Thermally Activated Flux Creep Estimated by Resistive and Magnetization Measurements in High T_c Superconducting Films" Physica. C185ー189. 2285-2286 (1991)

[Publications] N.Kobayashi: "Flux Creep in YBa_2Cu_3O_7 Films" Physica. C185ー189. 2353-2354 (1991)

[Publications] M.Matsukawa: "Critical Current Density and Dynamic Stability of HighーT_c Oxide Superconductor" Physica. C185ー189. 2477-2478 (1991)

[Publications] K.Watanabe: "CVD Route for High J_c Superconductors" Studies of High Temperature Superconductors. (1990)

[Publications] K.Noto: "High T_c Oxides" Handbook of Metallic CompositesーComposite Superconductorsー. (1991)

[Publications] K.Watanabe: "Polycrystalline Y_1Ba_2Cu_3O_<7-δ> Films Prepared by CVD Method" Proc.ICMC 91,Huntsville.

[Publications] K.Watanabe: "Magnetization Hysteresis in High Fields for QuenchーMeltーGrowth Processed Y_1Ba_2Cu_3O_7" Supercond.Sci.Technol.5. S288-291 (1992)

[Publications] K.Watanabe: "Critical Current Density and Its Related Problems in CVDーY_1Ba_2Cu_3O_7" Proc.2nd Tokai University Int.Conf.on Superconductivity,Honolulu(1991).

[Publications] K.Watanabe: "Anisotropy and Dimensional Characteristics in CVD Route Y_1Ba_2Cu_3O_<7-δ>" HighーTemperature Superconductors.

[Publications] S.Awaji: "Comparative Study of Critical Current Densities between Sputtered and CVD Processed YBa_2Cu_3O_<7-δ> Films" Proc.7th USーJapan WorkshoP on High Field Superconducting Materials,Wires and Conductors and Standard Procedures for HTSC Wires Testing,Fukuoka. 220-224 (1991)

[Publications] N.Kobayashi: "Anisotropic Behavior of J_c and Pinning Mechanism in HighーJ_c CVDーYBCO Films" Proc.7th USーJapan Workshop on High Field Superconducting Materials,Wires and Conductors and Standard Procedures for HTSC Wires Testing,Fukuoka. 196-201 (1991)

[Publications] N.Kobayashi: "Flux Creep and Pinning in highーJ_c YBCO Films" Proc.4th USーJapan Workshop on HTSC,Gaithersburg.

渡辺和雄東北大学, 金属材料研究所, 助教授 (30143027)