Study on structure and properties of X7R ceramics based on BaTiO 3 with high dielectric constants

Microstructures and dielectric properties of BaTiO₃-based X7R ceramics were studied. The dielectric constant at room temperature is about 4600, and the dielectric loss is 10^-2. The resistance is over 10¹²Ω·cm and TCC is less than ±15%. Under bias voltage, TCC is less than 13%. Therefore the materials meet EIA X7R specifications. The microstructures were studied by SEM and TEM. Inhomogeneous compositional distributions within the grains were observed that consisted of two main parts, each possessing a different temperature dependence of the dielectric constant. Multilayer capacitors were fabricated and showed outstanding performances. Dielectric constants of 5100 were achieved and components have passed the life test at 125°C for 1000 hr