Effect of the Reoxidation on Positive Temperature Coefficient Behavior of BaTiO3–Bi0.5Na0.5TiO3
Abstract:As a positive temperature coefficient of resistivity (PTCR) material, (1−x)BaTiO3–x(Bi0.5Na0.5)TiO3 (BT–BNT, 0.01≤x≤0.08) ceramics without any donor doping were prepared by a conventional solid-state reaction method. All samples were sintered in an N2 atmosphere at 1340°C, followed by reoxidizing at 800°–1100°C in air. The PTCR characteristics of BT–BNT ceramics were investigated in terms of BNT content, reoxidation temperature, and time. Room-temperature resistivity (RT) of simples sintered in N2 decreased to 102Ω·cm, and the jump in resistivity (maximum resistivity [max]/minimum resistivity [min]) was enhanced by three orders of magnitude through a suitable reoxidation process without sacrificing the RT. The Curie temperature (Tc) was shifted to a high temperature (>130°C) with an increase in the BNT content. With the addition of 4 mol% BNT, the obtained ceramic exhibited a low RT of 2 × 102Ω·cm, a typical PTC effect of max/min>103, and a Tc of 160°C.
Document Type: Research Article
Affiliations: School of Materials Science & Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
Publication date: 2010-06-01