Results
Title

Influences of Ba/Ti Ratios on the Positive Temperature Coefficient of Resistivity Effect of Y‐Doped BaTiO<sub>3</sub>–(Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub> Ceramics.

Authors

Senlin Leng; Guorong Li; Liaoying Zheng; Lihong Cheng; Jiangtao Zeng

Abstract

Y‐doped (1−x mol%)BaTiO3–x mol%(Bi1/2Na1/2)TiO3 (BBNTx) lead‐free positive temperature coefficient of resistivity (PTCR) ceramics were prepared using a conventional solid sintering method. The Ba/Ti ratio was adjusted to obtain the optimized PTCR property. The results show that all 0.2 mol% Y‐doped BBNT15 samples with various Ba/Ti ratios have formed a single tetragonal perovskite phase by sintering in an N2 atmosphere. The sample with 5 mol% (Bi1/2Na1/2)TiO3 has only a minor PTCR effect (maximum resistivity [ρmax]/minimum resistivity [ρmin]) when sintered in N2. However, the PTCR effect is enhanced over 3.0 orders of magnitude when the (Bi1/2Na1/2)TiO3 content is &gt;8 mol%. The PTCR characteristics of the samples with Ti excess are superior to those with Ba excess. The optimum composition of 0.2 mol% Y‐doped BBNT15 with Ba/Ti=0.99, sintered at 1250°C for 3 h in an N2 atmosphere, has a low room‐temperature resistivity (ρ25) of ∼100 Ω·cm and a high PTCR effect of ∼4.8 orders of magnitude with Tc around 190°C.

Subjects

CERAMICS; SINTERING; POWDER metallurgy; IRON metallurgy; PEROVSKITE; CONSTRUCTION materials

Publication

Journal of the American Ceramic Society, 2011, Vol 94, Issue 5, p1340

ISSN

0002-7820

Publication type

Academic Journal

DOI

10.1111/j.1551-2916.2011.04506.x