Concentration-driven structural stability and dielectric dispersion in lead free (Ba1−xSc2x/3)Zr0.3Ti0.7O3 ceramics

Abstract

Lead free scandium doped barium zirconate titanate (Ba1−xSc2x/3)(Zr0.3Ti0.7)O3 abbreviated as (BScZT) (x = 0.02, 0.04, 0.06, 0.08, 0.10) ceramics were prepared by the conventional solid state reaction route and their structural, microstructural and electrical properties were investigated experimentally. X-ray diffraction and Rietveld refinement analysis are indexed by considering cubic symmetry having space group Pm-3 m. Scandium ion (Sc3+) substitution induced A-site vacancies and distortion in three dimensional cation-oxygen networks leads to disorder in the local symmetry as identified in Raman spectra. The microstructural image shows formation of smaller grains of irregular shape and sizes along with aggregative characteristic with successive increase in Sc concentration. Lorentz type quadratic behavior in dielectric dispersion follows modified Curie–Weiss law and indicates a relaxor behavior with diffuse type of phase transition. A non-Debye type of relaxation behavior is observed in these materials. Variation of relaxation strength and diffuse parameters obey the Vogel–Fulcher relation. The ac conductivity highlights the hopping of bound charge carriers between the localized environment at lower temperature and translation hopping at higher temperature is modeled through universal dielectric response.