High-resolution transmission electron microscopy and cathodoluminescence scanning electron microscopu observations of SrTiO₃-based varistors

• Autorzy: Shiojiri M. , Isshiki T. , Saijo H. , Sato S. , Hitomi A.
• Konferencja: Polish-Japanese Joint Seminar on Materials Analysis (1-3.09.1997 ; Warsaw, Poland)
• Języki publikacji: EN

Abstrakty

EN

(Sr₀.₃₅Ba₀.₃₅Ca₀.₃₀)₁.₀₂₆TiO₃ ceramic varistors, which were produced by sintering in different reducing ambiences and by reoxidizing, have been investigated by high-resolution electron microscopy, electron probe microanalysis, and cathodoluminescence (CL) scanning electron microscopy. Varistors produced by ordinary sintering Po₂=10⁻⁸ Pa, 1400°C, 2 h) have low varistor coefficient are compos4ed of well-developed crystalline grains with facet boundaries. A severe reducting treatment (Po₂=10⁻¹² Pa, 1100°C, 2 h), added in the sintering process, damages the crystallinity in the grains by introducing many oxygen vacancies and changes the boundary zone to amorphous-like microcrystallites, which causes high varistor coefficient favourable for practical use. CL images vizualize the oxygen vacancies in the grains and glassy segregate phase (SiO₂-BaO-MgO) at boundary among three grains. It is found that the surface layer, which is composed of bright enclosed by dark boundary zones in CL images, is responsible for the varistor property.

• Wydawca: Institute of Electron Technology
• Czasopismo: Electron Technology
• Rocznik: 1998
• Tom: Vol. 31, No. 2
• Strony: 170--175
• Opis fizyczny: Bibliogr. 8 poz.

Twórcy

autor

Shiojiri M.

autor

Isshiki T.

autor

Saijo H.

autor

Sato S.

autor

Hitomi A.

• Kyoto Institute of Technology, Matsugasaki, Kyoto 606, Japan