Enhanced dielectric reliability in the X9R-type Bi1/2Na1/2TiO3-CaZrO3 relaxor ferroelectric ceramics

Abstract

High-performance dielectric ceramic capacitors for automotive applications require high operation temperature, thermal stability, and reliability for dielectric ceramics. A broad composition search has been carried out to replace the existing BaTiO3-based dielectrics having limited upper operating temperature due to the relatively low Curie temperature at around 120 degrees C. However, most of the developed compositions are too complicated and compositionally sensitive, making them difficult to commercialize. This study introduces a dielectrically reliable ceramic system based on Bi1/2Na1/2TiO3-CaZrO3(BNT) with a wide operation temperature range simply by adding paraelectric CaZrO3 (CZ). At 15 mol% addition of CZ to BNT, the permittivity variation within +/- 15% from -55 to 280 degrees C was achieved, which surpasses the EIA-X9R standard. Moreover, the dielectric reliability was shown with low dielectric loss (tan delta < 0.02) for the aforementioned temperature range and remarkable dielectric breakdown strength (similar to 260 kV/cm) at room temperature. Along with the proposal of a promising high-performance dielectric material, structural analysis and dielectric behavior investigation as a function of CZ contents were presented.