Development of Bi alloy insulator composites exhibiting metal-insulator-transition-like resistivity change
| Project/Area Number |
11555171
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Composite materials/Physical properties
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| Research Institution | Yamaguchi University |
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Principal Investigator |
MIKI Toshikatsu Yamaguchi University, Faculty of Engineering, Professor, 工学部, 教授 (70091212)
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| Co-Investigator(Kenkyū-buntansha) |
MURATA Takuya Yamaguchi University, Faculty of Engineering, Research Associate, 工学部, 助手 (70263796)
笹岡 秀紀 ベンチャービジネスラボラトリー, 非常勤研究員
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥6,400,000 (Direct Cost: ¥6,400,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | PTCR / over-current limiter / Bi-insulator composite / Bi alloy / metal-network / PTCR element / PTCR材料 / 温度感応型電流制限素子 / 導電性ネットワーク / チューブラ型 / スパッタパタン型 / Biガラスコンポジット / 衝撃圧成型 / 電極一括形成技術 / 金属ネットワーク切断モデル / 抵抗ジャンプ温度の低温化 / コンポジット材料 / 抵抗温度特性 / マイクロ波プロセス |
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| Research Abstract |
In this project, we have investigated "metal-insulator transition like PTCR material : Bi-insulator composite" to develop a new type of thermo-sensitive over-current limiter. The composite utilizes self-fixing process in metal-networks composed of Bi micro-particles depending on temperature change. Two prototypes have been made not only for verifying the PTCR mechanism but also for fabricating the electrical element. Besides, effect of microwave heating was studied to improve the PTCR property of the usual ceramics material. Obtained results are summarized as follows.
1) The ρ_<RT>, resistivity at room temperature, of Bi-polyimide composite increases after one cycle of heating and cooling process. On the other hand, in Bi-glass composite the ρ_<RT> was kept stable at 〜 1 Ωcm even with repeated thermal stresses. The ρ_<HT>, resistivity at high temperature, of the Bi-glass composite was higher than 10^6 Ωcm.
2) We proposed the PTCR mechanism for the Bi-glass composite in terms of "Bi-metal micro-networks" based on the microstructure observations. The hysterisis characteristic in ρ - T relation was expressed by freezing process of Bi micro-particles.
3) The critical temperature of the resistivity change in Bi-Sn alloy-glass composite was 〜 100K lower than that of Bi-glass composite, which is close to that of a PTCR BaTiO_3. However, the ρ - T relation shows semiconductor characteristics and the ρ_<HT>/ρ_<RT> is lower than 1.
4) We have made two prototypes of Bi-glass with PTCR property. One is micro-tube filled with Bi, and another is micro-pattern designed by sputtered Bi on a glass plate. In both elements Bi micro- particles with micron or lower in size should be packed in glass matrix for obtaining PTCR property.
5) Although ρ_<RT> of BaTiO_3 ceramic was reduced by microwave heating, the PTCR property is inferior to that of Bi-glass composite.
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Report
(4 results)
Research Products
(11 results)
