Effect of <TEX>$MnO_2$</TEX> Addition on the MIcrostructure and PTCR Characteristics in Semiconducting <TEX>$BaTiO_3$</TEX> Ceramics

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J. Korean Ceram. Soc. > Volume 32(5); 1995 > Article

Journal of the Korean Ceramic Society 1995;32(5): 567.

반도성 $BaTiO_3$ 세라믹스의 미세구조 및 PTCR 특성에 미치는 $MnO_2$ 첨가 효과

김준수, 김홍수, 백남석¹, 이병하¹

한국에너지기술연구소 에너지재료연구팀
¹명지대학교 공과대학 무기재료공학과

Effect of $MnO_2$ Addition on the MIcrostructure and PTCR Characteristics in Semiconducting $BaTiO_3$ Ceramics

ABSTRACT

The effect of MnO2 addition to 0.1mol% Sb2O3-doped BaTiO3 ceramics on microstructure and PTCR characteristics was studied. The PTCR characteristics was observed when 0.01 and 0.02 wt% MnO2 were added and sintered at 132$0^{circ}C$ for 1 hour. The characteristics can be explained by the changes in the number and size of the abnormal grain growth due to the liquid phase during sintering. when the amount of MnO2 addition was 0.03 wt%, the sample showed NTCR characteristics with room-temperature resistivity over 109 Ωm regardless of the sintering temperature. This behavior can be described by the microstructure change due to the abnormal grain growth and charge compensation effect by MnO2 added. The room-temperature resistivity was increased as the amount of MnO2 was increased. And the specific resistivity ratio (pmax/pmin) showed maximum at 0.02wt% MnO2.

Key words: Semiconducting $BaTiO_3$ ceramics, PTCR, Abnormal grain growth