Dielectric permittivity of PCLT/PVDF-TRFE nanocomposites

Abstract

The use of ferroelectric polymer films as pyroelectric sensors and ultrasonic transducers has attracted considerable interest. Polymer-based 0-3 nanocomposites, consisting of nanocrystalline calcium and lanthanum modified lead titanate (PCLT) powder embedded in a vinylidene fluoride-trifluoroethylene (polyvinylidenefluoride (PVDF)-trifluoroethylene (TRFE)) copolymer matrix, also have shown good potential in pyroelectric and piezoelectric applications. The dielectric permittivity and loss in these composites are important parameters characterizing their performance. In this study, the relative permittivity and loss of PCLT/PVDF-TRFE nanocomposites with various volume fractions of ceramic have been measured as function of frequency and temperature. The copolymer and nanocomposites exhibit a dielectric relaxation at the ferroelectric-to-paraelectric phase transition and another relaxation near room temperature (at ~1 MHz). The influence of the room temperature relaxation on transducer performance is discussed.