Structural and relaxor behavior in lead-free (Ba0.8Sr0.2)Ti1−x(Zn1/3Nb2/3)xO3 ceramics

The Solid solutions of (1−x)Ba0.8Sr0.2TiO3−xBa(Zn1/3Nb2/3)O3 (BST-BZN) with 0.025≤x≤0.15 were prepared by a high temperature solid-state reaction technique. The effects of the Ba(Zn1/3Nb2/3)O3 addition on the phase composition in the B site on structural and dielectric properties was investigated. The room temperature X-ray diffraction analyses of all ceramics revealed a perovskite phase with a composition dependent symmetry. The temperature and frequency dependence of the dielectric permittivity and losses have been explored. While ceramics of compositions x≤0.05 showed normal ferroelectric behavior, while ceramics with x≥0.1 were of relaxor type. It was found that degree of diffuseness and the relaxor effect increased, whereas the transition temperature (TC or Tm) decreased when both zinc and niobium were introduced in the Ba0.8Sr0.2TiO3 lattice. For the composition with x≥0.1, the frequency depend on Tm, satisfying the Vogel-Fulcher formula, which indicates a relaxor bahavior.