Dielectric behaviour of BaTiO3-based ceramic multilayer capacitors under high dc bias field

Abstract

The dielectric behaviour of X7R-MLCCs with different active layers under high dc bias field (up to 6.25 MV m−1) has been investigated in the whole measurement temperature range from 213 to 453 K. The results show that as the dc bias field increases, the dielectric permittivity in the whole measurement range and the frequency dispersion at lower temperature are both suppressed, while dielectric loss initially decreases till the temperature reaches about 423 K and subsequently remains invariable. These results are attributed to the response of the core-shell structure in grains to the applied dc bias field. Furthermore, the dielectric permittivity of X7R-MLCCs with more dielectric layers is more significantly affected because of a more powerful pinning effect of the residual stress between the dielectric layer and the Ni electrode on the migration of the domain walls and the influence of created interfaces on dielectric properties of the dielectric materials close to the interface. The Curie peaks for two samples shift towards higher temperature at a rate 0.55 × 10−5 K m V−1 in the presence of the dc bias field. It is more significant that an interesting field-induced transition from paraelectric phase to ferroelectric phase in the shell part was found at about 323 K and Curie temperature.