Electrical Characteristics of Multilayered Ceramic Capacitors Depending on BaTiO3 Particle Size

Multilayer ceramic capacitors were prepared with BaTiO3-based ceramics of different grain sizes (150–500 nm), having appropriate dielectric properties and high-temperature stability. The grain size effect on the dielectric properties and insulation resistivity of fine-grained BaTiO3 ceramics at room temperature and high temperatures under electric fields were investigated. The reduction in particle size has a strong effect on DC-bias characteristics and withstanding voltage characteristics per unit thickness. BaTiO3 ceramic capacitor with smaller grains had higher reliability under the DC bias and higher withstanding voltage per unit thickness due to the shell with para-electricity. The highly accelerated lifetime test showed that the insulation resistance with smaller particle size exhibited one order higher as the voltage increases at higher temperatures and the samples with a size of 500 nm had a sharp drop in insulation resistance at 200 V. Small particles (150, 250 nm) have a smaller product of insulation resistance and capacity than larger particles (500 nm). But, the withstanding voltage per unit thickness of the small particles (150, 250 nm) was 82, 71 V/μm, respectively, which was greater than 58 V/μm of the larger particles (500 nm). This is thought to be an effect of suppressing the movement of defects in the smaller particles because small grains have many grain boundaries.