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无机材料学报

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BaTiO3基PTCR陶瓷的复阻抗谱研究

唐小锋; 唐子龙; 周志刚   

  1. 清华大学材料科学与工程系新型陶瓷与精细工艺国家重点实验室, 北京 100084
  • 收稿日期:1999-12-03 修回日期:2000-02-01 出版日期:2000-12-20 网络出版日期:2000-12-20

Complex Impedance Spectra of BaTiO3 Based PTCR Ceramics

TANG XiaO-Feng; TANG Zi-Long; ZHOU Zhi-Gang   

  1. State Key Laboratory of New Ceramics and Fine Processing; Department of Materials Science and Engineering; Tsinghua University; Beijing 100084 China
  • Received:1999-12-03 Revised:2000-02-01 Published:2000-12-20 Online:2000-12-20

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摘要： 采用复阻抗方法，系统地研究了ＢａＴｉＯ３基ＰＴＣＲ陶瓷的电性能．通过Ｃｏｌｅ－Ｃｏｌｅ图，计算了样品的晶粒、晶界电阻值和弛豫时间常数，同时利用Ｈｅｙｗａｎｇ模型估算了势垒高度．Ｃｏｌｅ－Ｃｏｌｅ图分析表明，随着测试温度的提高，Ｃｏｌｅ－Ｃｏｌｅ圆将从单半圆向双扭线过渡，表明在居里温度附近，由于热激活出现了不同的缺陷类型．实验结果表明了ＰＴＣ效应是一种晶界效应，晶粒电阻随温度的变化呈ＮＴＣ特性，而晶界电阻却呈明显的ＰＴＣ特性．Ｈｅｙｗａｎｇ模型作为经典的理论模型，经过不断的完善，至今仍能对陶瓷材料ＰＴＣ现象的宏观机制做出明确的解析。

关键词: BaTiO3 PTCR, Cole-Cole图, 复阻抗谱, Heywang模型

Abstract: Complex impedance spectra of BaTiO3 with boron addition on the electrical characteristics of PTCR were studied. Cole-Cole plot shows a single semicircle
in room temperature (T<Tc) but shows a overlapping semicircle and skew circle above the Curie temperature (Tc<T<Tm), which may indicate
relaxational processes with multiple defects, such as VBa, Vo etc, from single defect such as VBa by thermal activation in the regions
of the grain boundary layer. The grain resistance, grain boundary resistance and relaxational time constant were calculated from the Cole-Cole plot and the barrier
height was calculated by the Heywang model. The results show that PTC effect originates from the grain boundary. The grain resistance exhibits NTC, but the grain boundary
resistance shows obviously PTC. Up to date, the Heywang model or Heywang-Jonker model is the most accepted model to explain the PTC mechanism by phenomenal explanation.

Key words: BaTiO3 PTCR, Cole-Cole plot, complex-plane impedance spectra, heywang model

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