Acta Phys. -Chim. Sin. ›› 2005, Vol. 21 ›› Issue (10): 1122-1126.doi: 10.3866/PKU.WHXB20051012

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Effect of Sm, Eu and Gd on Nb- doped TiO2 Varistors

TANG Zi-long ; MI Jia; ZHANG Zhong-tai; ZHOU Zhi-gang   

  1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084
  • Received:2005-03-21 Revised:2005-05-09 Published:2005-10-15
  • Contact: TANG Zi-long E-mail:tzl@tsinghua.edu.cn

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Abstract: The effect of Sm, Eu and Gd on electrical properties of a new class of polystalline ceramics based on TiO2 was investigated. The content of added Sm, Eu and Gd is 2% (atomic ratio), while that of the other addition is always maintained at a constant value. The disks were sintered at 1380 ℃ for 4 h. It was found that Sm, Eu and Gd can reduce the voltage values (corresponding to 1 mA current) of TiO2-based varistors effectively, but do not strongly influence the nonlinear values. The voltage values of the doped TiO2-based varistors were 12.7 V (Sm doped), 14.7 V (Eu doped) and 16.1 V (Gd doped). Through impedance analysis, it can be found that those rare-earth ions have great influence on the dielectric properties; the single addition of Sm or Gd could attain very low dielectric constant, low dissipation factor and very high resistivity. Sm, Eu and Gd distribute surrounding the TiO2 grains, but discontinuously.

Key words: Varistor, Rare- earth ions, Doping, Titania, Defect