Ca-acceptors in dielectric ceramics sintered in reducive atmospheres

Dielectric ceramics of the system (Ba,Ca)(Ti,Zr)O 3 (BCTZ) have been fired with BaO-excess in reducive atmosphere. By the influence of BaO-excess the Ca 2+-ions are shifted from the Ba- to the Ti-sites of the perovskite lattice. The solubility of Ca 2+ on Ti-sites is largely independent of the firin...

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Bibliographic Details
Published in:Journal of the European Ceramic Society 1995, Vol.15 (8), p.795-800
Main Authors: Hennings, D.F.K., Schreinemacher, H.
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Chemical industry and chemicals
Electrotechnical and electronic ceramics
Exact sciences and technology
Technical ceramics
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Summary:Dielectric ceramics of the system (Ba,Ca)(Ti,Zr)O 3 (BCTZ) have been fired with BaO-excess in reducive atmosphere. By the influence of BaO-excess the Ca 2+-ions are shifted from the Ba- to the Ti-sites of the perovskite lattice. The solubility of Ca 2+ on Ti-sites is largely independent of the firing atmosphere, but shows a pronounced temperature dependence. At 1400 °C ≅ 2 at.% Ca can be dissolved on the Ti-sites. Ca-ions on Ti-sites are strong electron acceptors. Highly insulating materials can be thus prepared in reducive atmospheres. The Ca-acceptors are electrically compensated by large numbers of ionized oxygen vacancies. Electromigration of the oxygen vacancies gives rise to ionic conductivity, resulting in low life stability of multilayer capacitors, sintered in reducive atmosphere.
ISSN:0955-2219
1873-619X
DOI:10.1016/0955-2219(95)00043-T