Preparation of (La + Nb)-co-doped TiO₂ and its polyvinylidene difluoride composites with high dielectric constants

Abstract

Numerous studies have shown that ceramic materials with high dielectric constants and low dielectric losses can be obtained using donor–acceptor-doped TiO2. In this study, (La + Nb)-co-doped TiO2 [(La0.5Nb0.5) x Ti1−x O2 x-LNTO] ceramic powders were prepared using the sol–gel method. XRD demonstrates that LNTO is a rutile phase, and the lattice parameters change after doping, while X-ray photoelectron spectroscopy explains the doping mechanism, with doping of TiO2 producing oxygen vacancies and Ti3+, which form defective dipoles with the dopant ions to increase the dielectric constant of the material. The dielectric properties were investigated by physically co-blending x-LNTO/polyvinylidene difluoride (PVDF) composites. Compared with the TiO2/PVDF composite, the dielectric properties of the x-LNTO/PVDF composite were more excellent. The dielectric constant of 5-LNTO/PVDF reached 36.96, which was higher than that of the TiO2/PVDF composite (19.49) at a filler addition of 60 wt% and a frequency of 1 kHz.