Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference (한국전기전자재료학회:학술대회논문집)

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Microstructure and PTCR characteristic of high $T_c$ lead-free ((1-x)$BaTiO_3-x(Bi_{1/2}Na_{1/2})TiO_3$ characteristic

High $T_c$ Pb-free (1-x)$BaTiO_3-x(Bi_{1/2}Na_{1/2})TiO_3$ 세라믹의 미세구조와 PTCR 특성

  • Kim, Chul-Min (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Cho, Yong-Soo (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Jeong, Young-Hun (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Lee, Young-Jin (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Lee, Mi-Jae (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Paik, Jong-Hoo (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Lee, Woo-Young (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.) ;
  • Kim, Dae-Joon (Korea Institute of Ceramic ENG. & TECH, Yonsei University, and HIEL co.)
  • 김철민 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 조용수 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 정영훈 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 이영진 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 이미재 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 백종후 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 이우영 (요업(세라믹)기술원, 연세대학교, (주)하이엘) ;
  • 김대준 (요업(세라믹)기술원, 연세대학교, (주)하이엘)
  • Published : 2008.11.06
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Abstract

Microstructure and positive temperature coefficient of resistivity (PTCR) characteristics of $0.9BaTiO_3-0.1(Bi_{0.5}Na_{0.5})TiO_3$ [BaBiNT] ceramics doped with $Nb_2O_5$ were investigated in order to develop the Pb-free high Curie temperature ($T_c$)(>$160^{\circ}C$) PTC thermistor. The BaBiNT ceramics showed a tetragonal perovskite structure, irrespective of the added amount of $Nb_2O_5$. They also have a homogeneous microstructure. The resistivity of BaBiNT ceramics was gradually decreased by doping $Nb_2O_5$, which might be due to $Nb^{+5}$ ions substituting for $Ti^{+4}$ sites. The PTCR characteristics of BaBiNT ceramics appeared when the amount of doped $Nb_2O_5$ exceeded 0.0025mol%. Moreover, the abrupt grain growth was observed for the 0.03mol% $Nb_2O_5$added BaBiNT ceramics. It showed an especially high $T_c$ of approximately $172^{\circ}C$ and good PTCR characteristics of a high $\rho_{max}/\rho_{min}$ ratio ($2.96\times10^3$), a high resistivity temperature factor (11.40/$^{\circ}C$) along with a relatively low resistivity ($3.5\times10^4\Omega{\cdot}cm$).

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