Dielectric responses of modified BaTiO3 ceramics in multilayer ceramic capacitors to the combined uniaxial stress and dc bias field

Dielectric measurements of modified BaTiO3 in a multilayer ceramic capacitor (MLCC) show that the application of external uniaxial stress perpendicular to electric field in a MLCC can lead to a slight increase in the dielectric permittivity. The additional application of a dc bias results in a significantly suppressed dielectric permittivity in the temperature range from 228 to 453 K. These observations can be explained as a result of domain wall movements in grains with a core-shell structure, due to the combined stress and dc bias field. As the dc bias increased up to 5.6 MV/m, the Curie peak, which has diffuse phase transition characteristics in the absence of dc bias, becomes sharper, and two new peaks are induced at about 250 and 315 K. Furthermore, the first order paraelectric-ferroelectric phase transition of the modified BaTiO3 ceramic becomes stronger with increasing dc bias when a uniaxial stress is also applied.