ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 54, (3) 258 - 262 (2010)

Yuan Ying, Zhou X. H., Li B., Zhang S. R.
The State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, People’s Republic of China

Keywords: Barium titanate, Sodium titanate bismuth, High-temperature capacitor, Electrical properties

High-temperature capacitor materials were prepared in a BaTiO₃ (BT)-Bi0.5Na0.5TiO₃ (BNT)-BiNbO₄ (BN)-Nb₂O₅ system. The effects of BN and Nb₂O₅ on the dielectric properties and microstructure of 5 mol% BNT-doped BT ceramics were investigated. The dielectric constant peak at TC was suppressed with the addition of BN, whereas an enhancement in the dielectric constant at lower temperatures was observed. In the case of 3 mol% BN addition, the temperature characteristic of capacitance satisfied the EIA X8R specification (-55 to 150°C, ΔC/C25°C less than ±15 %). Scanning electron microscope and X-ray diffraction analyses suggested that a small amount of secondary phases existed in all the samples and the proportion of the secondary phases decreased with the addition of BN. When Nb₂O₅ was added to BT–BNT–BN ceramics, the dielectric constant at higher temperatures was markedly enhanced with an increase in Nb₂O₅ content. Therefore, the high-temperature specification (-55 to 200°C, ΔC/C25°C less than ±15 %) is met when 3 mol% BN and 4 mol% Nb₂O₅ was added to 5 mol% BNT-doped BT ceramics, with a dielectric constant greater than 1200 and a dielectric loss lower than 1.5 %.

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