Structural and dielectric properties of La substituted polycrystalline Ca(Ti0.5Fe0.5)O3

Polycrystalline Ca1−x Lax(Ti0.5Fe0.5)O3 were prepared by the standard solid state reaction technique. Pellet shaped samples prepared from each composition were sintered at 1573 K for 5 h. The X-ray diffraction analysis indicated the formation of a single-phase orthorhombic structure. The lattice parameters as well as densities increased but the average grain sizes decreased with the increase of La content. The dielectric measurements were carried out at room temperature as a function of frequency and composition. The experimental results revealed that dielectric constant (ɛ′) decreased but dielectric loss (tan δ) and ac electrical conductivity (σ ac) increased as frequency increased. The composition dependence of ɛ′ and tan δ indicated that they decreased with the increase of La content. The σ ac was derived from the dielectric measurements and it is concluded that the conduction in the present samples is due to mixed polarons hopping.