Electrostrictive mechanism of microwave losses in a planar strontium titanate film capacitor

An analysis is made of the dielectric losses in the microwave range in a planar ferroelectric capacitor caused by electrostrictively excited sound in the ferroelectric in the presence of a bias field (induced piezoeffect). An approximate expression is obtained for the dielectric loss tangent as a function of the bias field and the frequency. Numerical estimates are made for singlecrystal strontium titanate at 78 K. This loss mechanism may be a determining factor for the fabrication of planar capacitors using high-quality ferroelectric films having properties close to those of the single crystal.