Electric-field-enhanced permittivity dependence on temperature and cooling rate

The electric-field-enhanced effect of permittivity is one of the most important physical properties of KTa1-xNbxO3 in paraelectric, thus greatly affecting the performance of electro-optic modulator and deflector. We studied the temperature dependence of the electric-field-enhanced effect and the effect of supercooling on it. We found that this enhanced effect is closely related to the Frohlich entropy, with a minimum value that corresponds to the strongest field enhancement effect. We further discovered that supercooling could improve the field-enhanced effect by 15%, because of the small polar nanoregion (PNR) size and high polarization. In addition, we propose a novel model to describe the electric-field-enhanced characteristic of the permittivity. The model can well explain the enhanced permittivity under DC electric field and reveal that the field enhancement of permittivity is mainly caused by reorientation of PNRs gradually activated by the DC electric field.