Dielectric Investigations of Nanoferroelectric BaTiO₃

Abstract

In this work, dielectric investigations of nanoferroelectric barium titanate are presented. Barium titanate samples were prepared by an aqueous acetate-peroxocitrate sol-gel method. Six samples were sintered at 800–1000°C. Scanning electron microscope (SEM) was used to study average grain size. The crystallites obtained at higher temperature (1000°C) were slightly larger (∼ 35–40 nm.) than those obtained at 800°C (20–25 nm). The X-ray powder diffraction (XRD) studies indicate that samples are barium titanate of cubic symmetry, but also secondary phases are present. Five samples have similar dielectric properties. The dielectric permittivity has a small maximum at the phase transition temperature and indicates that these five samples have ferroelectric behaviour. The Curie temperature is lowered with decreasing grain size. But one sample has different dielectric properties. The real permittivity part has a broad maximum and the imaginary permittivity part has peaks at different temperature at different frequency. This indicates that this sample is similar to dipolar glasses. Perhaps it contains more secondary sintering products than other five samples.

Keywords:

• Barium titanate
• nanoferroelectrics
• dielectric spectroscopy
• phase transitions

Acknowledgment

This work was supported by Lithuanian Science and Study Foundation.