Electrical and Chemical Characteristics of the Grain Boundaries of Semiconducting $BaTiO_3$ Ceramics Prepared with Surface-Coated Powders

표면 코팅된 분말을 이용하여 제조된 반도성 $BaTiO_3$ 소결체의 입계 화학 및 전기적 특성

  • 박명범 (인하대학교 재료공학부) ;
  • 김정돈 (한국과학기술연구원 세라믹스연구부) ;
  • 조남희 (인하대학교 재료공학부)
  • Published : 2000.04.01

Abstract

Grain boundary chemistry and electrical characteristics of polycrystalline BaTiO3 ceramics, which were prepared with sol-gel surface-coated semiconducting powders, were investigated. Mn ions were coated on the powder surface by sol-gel coating-techniques. The additives coated on the surface of the powders were observed to be present near the grain boundaries of the ceramics. The ceramics exhibit the PTCR characteristics with a resistivity jump ratio(Pmax/Pmin) of about 2$\times$103. With raising the temperature from room temprature to 20$0^{\circ}C$, the oxidation state of the Mn ions varied from Mn3+ to Mn2+ in the coating layers. Near the grain boundaries an excessive negative charge layer of about 20nm was formed.

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