Influence of sintering temperature on core–shell structure evolution and reliability in Dy modified BaTiO₃ dielectric ceramics

Abstract

The formation of core–shell structure plays a very important role in temperature stable BaTiO3‐based dielectric ceramic for multilayer ceramic capacitors applications. In this work, the rare earth Dy modified BaTiO3 dielectric ceramics have been prepared by chemical coating method, which possess high dielectric constant and high insulation resistivity, satisfying the EIA X7R specification. The existence of core–shell structure was proven by transmission electron microscopy observation and energy dispersive spectroscopy analysis. Experimental results show that the sintering temperature has a strong effect on the core–shell structure evolution in Dy‐doped BaTiO3 ceramics. Thus, selecting an appropriate sintering temperature is conducive for improving the temperature stability for multilayer ceramic capacitors applications. Furthermore, impedance analysis and the highly accelerated lifetime test show that the core–shell structure evolution has a closely relationship with the reliability accompanied by the increasing of sintering temperatures.

Core–Shell Lead–Free Piezoelectric Ceramics: Current Status and Advanced Characterization of the Bi1/2Na1/2TiO3–SrTiO3 System

“…Table reveals that systematic structure–property relationships have been performed mostly in dielectrics. This is attributed to the implementation of core–shell BT‐based dielectrics in high‐temperature capacitors owing to their temperature‐insensitive relative permittivity. However, limited research has been performed in core–shell piezoceramics.…”

“…This approach represents a new alternative for further electromechanical properties optimization in the search of environmentally friendly piezoceramics. For instance, the possibility of increasing breakdown strengths with an engineered core–shell microstructure has already been shown, where it was pointed out that an optimum design consists of a controlled shell thickness with a low relative permittivity, high insulation resistance, and density …”

“…For instance, for the poling procedure and large signal applications it is important to point out that dielectric breakdown is improved with a core-shell microstructure due to a better local electric field distribution 123,124 and resistivity. 69 Moreover, it should also be noted that in some KNNbased piezoelectrics the electromechanical properties actually decreased with a core-shell microstructure. 91,92 This indicates that in certain materials the core-shell structure may not be desirable.…”

“…The core–shell approach is an alternative route to achieve high and reliable electromechanical properties with a reduced hysteresis. Core–shell materials have been successfully implemented into dielectrics with exceptional, temperature stable properties . Although this approach holds much promise for piezoelectrics, it has been to date barely studied.…”

The role of diffusion behavior on the formation and evolution of the core‐shell structure in BaTiO3‐based ceramics

“…Despite the fact that the core‐shell structure formation mechanism remains uncertain, general consensus has been reached that a limited diffusion process of dopants into BT grains results in heterogeneous distribution of elements and the formation of a core‐shell structure . In addition, a core‐shell structure is a metastable state in thermodynamics, and it will evolve to be a stable homogenous state as the processing conditions such as the sintering temperature, dwelling time, coating method, starting particle size, and internal stress change . It has been demonstrated that the stabilization of a core‐shell structure is mostly dependent on the low diffusion rate of additives into the BT core .…”