Analysis on dielectric response of polar nanoregions in paraelectric phase of relaxor ferroelectrics

Ferroelectric phase shifter is preferred to be used in paraelectric phase due to the demand of low loss. Dielectric response of polar nanoregions was analyzed in the present study, including their characteristics and contributions both to dielectric polarization and tunability. The corresponding dielectric constant of paraelectric phase consists of two parts, intrinsic one and extrinsic one. The former one, which depends on volume fraction of paraelectric phase, was mainly contributed by ionic displacement. The latter one, proportional to the volume specific surface of nanoregions, was mainly contributed by the boundary vibration of polar nanoregions. The possible mechanism of tunability in paraelectric phase consists of intrinsic tunability of polarization of ionic displacement and extrinsic tunability of boundary vibration of polar nanoregions.