Formation of Core-Shell Structure in Ultrafine-Grained BaTiO3-Based Ceramics Through Nanodopant Method


  • C. Randall—contributing editor

  • This work was supported by the National Science fund for distinguished young scholars (grant no. 50625204), Science Fund for Creative Research Groups (grant no. 50621201), and by the Ministry of Sciences and Technology of China through the National Basic Research Program of China (973 Program 2009CB623301) and through the 863-program under grant 2006AA03Z0428, and also supported by Samsung Electro-Mechanics Co. Ltd.

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The formation of core-shell structure is the key issue of temperature stable barium titanate-based dielectric ceramic for multilayer ceramic capacitor application. It is difficult to obtain and observe the core-shell structure in ceramic grains when the grain size becomes smaller, especially to sizes <200 nm. A nanodopant method has been developed for the preparation of ultrafine-grained barium titanate-based ceramics with grain size below 200 nm. The existence of core-shell structure was proved by transmission electron microscopy observation and energy-dispersive spectroscopy analysis. High-performance X7R dielectric ceramics were produced in a reducing atmosphere by normal sintering and two-step sintering method. The dielectric constant at room temperature could reach over 2000, with a low dielectric loss at about 1.0% and high insulation resistivity ∼1012Ω·cm.