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Direct measurements of of grain boundary properties and mechanism of electroceramics.

直接测量电陶瓷的晶界特性和机理。

基本信息

批准号：
06650738
负责人：
SAKURAI Osamu
金额：
$ 1.28万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06650738/
关键词：
Grain boundary of ceramics Electrical measurements of narrow region Varistor

项目摘要

The electrical properties in very narrow region of a single grain boundary in Ladoped SrTiO_3 crystals were measured by using the micromanipulatoR.The sample having one grain boundary was prepared from semi conductive SrTiO_3 crystals having mosaic structure prepared by xenon-arc image floating zone method. The nonlinear relation of voltage and current was observed in the every grain boundaries. Although there were no electrical effects from the neighbor grains in the single grain boundary sample, the break down voltage (Vb) and nonlinear coefficient (alpha) varied 0.5 to 3.5 V and 1 to 7 respectively. The varistor characteristic was independent from the directions of crystals. After heat treatment in reduced atmosphere, the varistor characteristics was disappears. The reduced samples were re-oxidized at high temperature, then teh varistor characteristics were observed again. The voltage-current characteristics of grain boundary were changed reversibly by oxidation or reduction of the sample. The break down voltage was increase with oxidation temperature and time, but nonlinear coefficient (alpha) was almost constant.In the sample, cut the SrTiO_3 FZ-single crystal into two pic es and oxidized them and then contacted them mechanically in same direction before separation, the nonlinear relation of voltage and current was observed same as the grain boundary in the FZ-crystals.

用氙弧浮区法制备了具有镶嵌结构的半导体SrTiO_3晶体，用显微操作仪测量了Laoped SrTiO_3晶体中单个晶界的很窄区域内的电学性质。在每个晶界上观察到电压与电流的非线性关系。虽然在单个晶界样品中没有来自相邻晶粒的电效应，但是击穿电压（Vb）和非线性系数（α）分别在0.5至3.5V和1至7之间变化。压敏电阻特性与晶体取向无关。在还原气氛中热处理后，压敏电阻特性消失。还原后的样品在高温下再次氧化，然后再次观察压敏特性。晶界的伏安特性随样品氧化或还原而发生可逆变化。击穿电压随氧化温度和氧化时间的增加而增加，非线性系数α基本不变，在样品中，将SrTiO_3FZ单晶切成两片，氧化后在分离前同向机械接触，观察到与FZ晶体中晶界相同的电压-电流非线性关系。