Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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The Effect of Grain Boundary Diffusion on the Boundary Structure and Electrical Characteristics of Semiconductive $SrTiO_3$ Ceramics

입계확산에 의한 반도성 $SrTiO_3$ 세라믹스의 입계구조 및 전기적 특성 변화

  • 김태균 (인하대학교 무기재료공학과) ;
  • 조남희 (인하대학교 무기재료공학과)
  • Published : 1997.01.01
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Abstract

Semiconductive SrTiO3 ceramic bodies were prepared by conventional ceramic powder processes in-cluding sintering in a reducing atmosphere. Sodium or potassium ions were diffused from the surface of the sintered bodies into the inner region using thermal diffusion process at 800-120$0^{\circ}C$. The effects of such ther-mal treatments on the electrical and chemical characteristics of the grain boundaries were investigated. The presence of sodium or potassium ions at grain boundaries produces non-linear current-voltage behaviors, electrical boundary potential barriers of 0.1-0.2eV, and threshold voltages of 10-70V. The diffused ions form diffusion layers with thicknesses of 20-50nm near the grain boundaries, reducing the concentration of strontium and oxygen.

SrCO3 TiO2, 그리고 Nb2O5를 출발원료로 하여 환원분위기하에서 반도성 SrTiO3 소결첼르 제조하였다. 반도성 다결정 소결체 내에서 acceptor 역할을 할 수 있는 Na과 K 이온을 입계를 따라 80$0^{\circ}C$~120$0^{\circ}C$ 온도범위에서 확산시킨 후, 열처리조건에 따른 입계의 전기적 화학적 특성을 고찰하였다. 이차열처리한 소결체의 입계에는 일정한 전기적 포텐셜장벽과 이에 상관된 전자고갈영역이 형성되어 비선형적인 전류-전압 특성을 보이고 문턱전압(threshold voltage)은 10~70V, 입계포텐셜장벽은 0.1~2eV의 크기를 나타내었다. Na과 K 이온은 입계로부터 입자내부로 확산하여 20~50 nm 깊이의 확산층을 형성하며, 이들 확산층에서 Na 또는 K과의 치환에 기인하여 Sr농도가 감소하였으며 치환에 따른 전기적 중성유지를 위하여 산소 vacancy 농도가 증가하였다.

Keywords

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