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Development of Bi alloy insulator composites exhibiting metal-insulator-transition-like resistivity change

开发具有金属-绝缘体过渡状电阻率变化的铋合金绝缘体复合材料

基本信息

批准号：
11555171
负责人：
MIKI Toshikatsu
金额：
$ 4.1万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

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.

在这个项目中，我们研究了“金属-绝缘体转变如PTCR材料：双绝缘体复合材料”，以开发一种新型热敏过流限制器。该复合材料利用由 Bi 微粒组成的金属网络根据温度变化进行自固定过程。制作了两个原型，不仅用于验证 PTCR 机制，还用于制造电气元件。此外，还研究了微波加热的效果，以改善常用陶瓷材料的PTCR性能。得到的结果总结如下： 1)Bi-聚酰亚胺复合材料的室温电阻率ρ_<RT>在一次加热和冷却过程后增加。另一方面，在双玻璃复合材料中，即使在重复的热应力下，ρ_<RT>仍保持稳定在约1Ωcm。 Bi-glass复合材料的高温电阻率ρ_<HT>高于10^6 Ωcm。2)基于微观结构观察，我们从“双金属微网络”的角度提出了Bi-glass复合材料的PTCR机制。 ρ-T关系的滞后特性通过Bi微粒的冻结过程来表达。3)Bi-Sn合金-玻璃复合材料的电阻率变化临界温度比Bi-玻璃复合材料低〜100K，与PTCR BaTiO_3的电阻率变化临界温度接近。然而，ρ - T 关系显示出半导体特性，并且 ρ_<HT>/ρ_<RT> 低于 1.4) 我们已经制作了两个具有PTCR 特性的双玻璃原型。一种是充满Bi的微管，另一种是在玻璃板上溅射Bi设计的微图案。在这两种元素中，为了获得PTCR性能，必须将尺寸为微米或更小的Bi微粒填充在玻璃基体中。5)尽管微波加热降低了BaTiO_3陶瓷的ρ_<RT>，但其PTCR性能不如Bi-玻璃复合材料。