Effect of Pr₆O₁₁ Doping on the Microstructural and Electrical Properties of ZnO-Pr₆O₁₁-Co₃O₄-Cr₂O₃-SnO₂ Varistors

Abstract:

ZnO-Pr₆O₁₁-Co₃O₄-Cr₂O₃-SnO₂ varistors with different doping levels of Pr₆O₁₁ (0.25-2 mol%) were prepared at 1300 °C with conventional ceramic processing, and the effect of Pr₆O₁₁ doping on the microstructure and electrical properties of the varistor materials were investigated. The results indicated that the doped Pr₆O₁₁ basically existed at the boundary of ZnO grains in the varistor ceramics, and SnO₂ might enter into the lattice of ZnO grains or precipitate in reaction with Pr₆O₁₁ into Pr₂Sn₂O₇ at the gain boundaries particularly where there were three or more ZnO grains. The analysis of scanning electron microscopy further revealed that Pr₆O₁₁ doping would inhibit the growth of ZnO grains, resulting in decreasing ZnO grain size with increasing doping level of Pr₆O₁₁. The measured electric-field/current-density characteristics of the samples showed that the varistor voltage increased with increasing doping level of Pr₆O₁₁ when the doping level was no more than 1.5 mol%, and the nonlinear coefficient of the varistors increased with increasing doping level of Pr₆O₁₁ up to no more than 1.0 mol% in the varistors, respectively.

• Periodical: Key Engineering Materials (Volume 633)
• Pages: 308-312
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.633.308
• Online since: November 2014
• Authors: Xiu Li Fu*, Hai Feng, Zhi Jian Peng
• Keywords: Doping, Electrical Properties, Pr₆O₁₁, ZnO Varistor

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