Effect of Dy 2 O 3 addition on microstructure, electrical properties, and aging behavior of ZnO-V 2 O 5 -MnO 2 -CoO varistor ceramics

Author： Nahm Choon-W.

Publisher： Springer Publishing Company

ISSN： 0957-4522

Source： Journal of Materials Science: Materials in Electronics, Vol.22, Iss.11, 2011-11, pp. : 1674-1680

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Abstract

The microstructure, electrical properties, and aging behavior of ZnO-V₂O₅-MnO₂-CoO-Dy₂O₃ varistor ceramics were investigated for different contents of Dy₂O₃. The microstructure consisted of ZnO grain as a main phase and secondary phases such as Zn₃(VO₄)₂, ZnV₂O₄, and DyVO₄. The average grain size increased from 7.6 to 10.1 μm and the sintered density slightly increased from 5.53 to 5.57 g/cm³ with the increase of Dy₂O₃ content. The varistor ceramics added with 0.05 mol% Dy₂O₃ exhibited the most nonlinear properties, with nonlinear coefficient of 30, and the highest stability against DC-accelerated aging stress. The Dy₂O₃ acted as an acceptor due to the decrease of donor density in the range of 2.73 × 10¹⁸/cm³ to 1.28 × 10¹⁸/cm³.