Electrical Characteristics of Multilayered Ceramic Capacitors Depending on BaTiO₃ Particle Size

Abstract

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.