Dielectric properties of iron-containing bismuth titanate solid solutions with a layered perovskite structure

The complex oxides based on bismuth titanate with substituting iron atoms Bi4Ti2.98Fe0.02O11.99, Bi4Ti2.5Fe0.5O11.75, and Bi4Ti2Fe1O11.5 have been studied using dielectric spectroscopy in the frequency range from 30 to 106 Hz at a temperature of 296 K. The frequency dependences of permittivity ɛ′, dielectric loss ɛ″, and complex part of conductivity σ′ have been studied, and the dependences ɛ″(ɛ′) have been constructed. The microstructure images of the studied ceramic materials have been obtained using atomic force microscopy. It has been shown that, as Fe3+ ions are introduced as substituting atoms, there is a critical concentration x (0.5 < x < 1) above which the dielectric properties substantially change with variations in the number of perovskite-like layers, and the correlation is observed between the concentration of substituting Fe atoms and the grain size on the surface of the samples.