A. Tagantsev, dc-electric-field-induced microwave loss in ferroelectrics and intrinsic limitation for the quality factor of a tunable component, APPL PHYS L, 76(9), 2000, pp. 1182-1184
An effect of dc electric field on the intrinsic microwave loss in incipient
ferroelectrics is theoretically studied. The contribution of the so-called
field-induced quasi-Debye mechanism, which is related to the relaxation of
phonon distribution function, is evaluated. It is found that the dc-field-
induced loss is controlled by the relaxation of the acoustic-phonon distrib
ution function rather that the distribution function of the soft-mode phono
ns, as was earlier assumed. The theory gives qualitative explanation for a
dramatic field-induced increase of the loss factor recently reported for KT
aO3 and SrTiO3 bulk resonators with superconductive electrodes. Numerical e
stimates performed for KTaO3 are in a good agreement with the experimental
data. The field and frequency dependence of the figure of merit of a ferroe
lectric-based tunable microwave component is evaluated. (C) 2000 American I
nstitute of Physics. [S0003-6951(00)02109-4].