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

Abstract

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 o200 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 energydispersive 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 B10 12 X . cm.

Electrical and reliability characteristics of Mn-doped nano BaTiO3-based ceramics for ultrathin multilayer ceramic capacitor application

“…1 Thus, the grain size of BT should decrease to about 200 nm or less, while at the same time the so-called "core-shell" structure should be preserved to fulfill the temperature-stable characteristics of the capacitance and a reliable performance in MLCCs. [22][23][24][25] At the same time, the reduction of the dielectric layer thickness directly implies the increase in the electric field applied to the dielectric layers. 9,26,27 Consequently, the reliability research is urgently important in ultra-thin MLCCs.…”

Microstructure effect on dielectric Properties of MgO-doped BaTiO3–BiYO3 ceramics

“…However, its dielectric constant will drop rapidly above the Curie temperature T c (about 120 1C), according to the CurieWeiss law ε¼ C/(TÀ T c ), which does not satisfy the requirement of high thermal stability. Currently many studies have been carried out to modify BT-based materials, so as to raise the Curie temperature and broaden the dielectric maxima, which would meet the temperature characteristics of X8R or X9R specification [4,5].…”

Dielectric properties of Bi-Doped BaTiO3-based ceramics synthesized by liquid-state method

“…Generally, nano-sized BaTiO 3 -based powder is usually prepared via wet chemical method such as the precipitation method [5,6], the sol-gel press [7], and traditional solid-state method [8][9][10][11][12]. In general, a traditional solid-state method is used to prepare MLCCs ceramics.…”