Acta Metallurgica Sinica (English Letters) ›› 2011, Vol. 24 ›› Issue (4): 315-320.DOI: 10.11890/1006-7191-114-315

• 研究论文 • 上一篇    下一篇

(1-x)BaTiO3+(x)La2/3Sr1/3MnO3 复合材料的结构和电子性质

周正有   

  1. 南昌大学
  • 收稿日期:2010-07-13 修回日期:2010-11-02 出版日期:2011-08-25 发布日期:2011-08-18
  • 通讯作者: 周正有

Structure and electrical properties of (1-x)BaTiO3+(x)La2/3-Sr1/3MnO3 composites

Zhengyou ZHOU1，Yu LEI2   

  1. 1. School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China
    2. College of Vocational Education, East China Jiaotong University, Nanchang 330031, China
  • Received:2010-07-13 Revised:2010-11-02 Online:2011-08-25 Published:2011-08-18
  • Contact: Zhengyou ZHOU

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摘要： 本文采用液相烧结法制备BaTiO3粉末，并研究了(1-x)BaTiO3+(x) La2/3Sr1/3MnO3 (LSMO)结构和电子性质。X-射线衍射谱分析表明添加NaCl助烧剂可以明显降低烧结温度，且制备的BaTiO3粉末较纯和颗粒小。(1-x)BaTiO3+(x) La2/3Sr1/3MnO3 (LSMO)复合材料的X-r射线谱表明只有BaTiO3和LSMO两相存在，没有新相生存。阻抗图谱显示复合材料的晶界电阻受抑制。电阻-温度曲线显示掺入LSMO显著降低了电阻率。x=0.2的样品只显示PTC效应，而x=3的样品在小于68℃时显示PTC效应，而在高于68℃显示NTC效应。用相关的机理对这些现象进行了阐述。

Abstract: Liquid-phase sintering method was used to prepare BaTiO3 powders and the structure and electrical properties of (1-x)BaTiO3+(x)La2/3Sr1/3MnO3 (LSMO) composites were investigated. The results of X-ray diffraction showed that the prepared BaTiO3 powders were pure and fine, indicating that sintering temperature was effectively lowered when the NaCl sintering aid was added. X-ray diffraction patterns of \linebreak\noindent (1-x)BaTiO3+(x)La2/3Sr1/3MnO3 (LSMO) composites showed that LSMO and BaTiO3 phases were coexistent and no other phases were detected. The impedance spectra showed that the resistance of grain boundaries for LSMO-doped samples was suppressed. The resistivity-temperature measurements showed that room-temperature resistivity of the composites was lowered from insulator for pure BaTiO3 ceramic to 103Ω•m for the x=0.3 sample. The sample of x≤0.2 showed the positive temperature coefficient (PTC) effect whereas the x=0.3 sample exhibited PTC effect at temperatures below 68 ℃ and then negative temperature coefficient (NTC) effect at temperatures above 68 ℃. The related mechanism has been elucidated.

Key words: Positive temperature coefficient, Composite, Impedance spectra, Resistivity