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Effects of Niobiumª²Doping on the Structure and Electrical Properties of (Ba,Bi,Na)TiO3-based PTCR Ceramics

Author(s): LI Yan-Yan,LI Guo-Rong,WANG Tian-Bao,ZHENG Liao-Ying,LENG Sen-Lin,YIN Qing-Rui

Journal: Journal of Inorganic Materials
ISSN 1000-324X

Volume: 24;
Issue: 2;
Start page: 374;
Date: 2009;
Original page

Keywords: PTCR | lead-free | high curie temperature | (Bi1/2Na1/2) TiO3

(Ba, Bi, Na)TiO3-based PTCR Ceramics (BBNMT) doped with Nb2O5 (0.1mol%, 0.3 mol%, 0.5mol%, 0.7mol%) were prepared by the solid state reaction method and annealing in the reduction atmosphere. The microstructures and electrical properties of BBNMT were investigated. The results show that with the increase of Nb2O5 contents, the grain size increases firstly and then decreases, which indicates that there exists an optimal content of Nb2O5. The low resistivity PTC ceramic materials are obtained when the content of Nb2O5 is 0.5mol% with the room temperature resistivity(¦ϼSUB>25) of 1.06¡�03¦¸¡¤cm, the Curie temperature (Tc) of 183¡䪠and the resistivity jump (¦ϼSUB>max/¦ϼSUB>min) of 1.0¡�04. By analyzing the impedance spectroscopy, the influence of the grain phase, grain boundary phase and ¡°shell phase¡± on the resistivity are discussed, the interaction mechanism of Nb2O5 donor in PTCR ceramics are also studied.

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