Morphotropic phase boundary and electrical properties of 1−x[Bi0.5Na0.5]TiO3 –xBa[Zr0.25Ti0.75]O3 lead-free piezoelectric ceramics

Abstract Lead-free solid solutions (1− x )Bi 0.5 Na 0.5 TiO 3 (BNT)– x BaZr 0.25 Ti 0.75 O 3 (BZT) ( x =0, 0.01, 0.03, 0.05, and 0.07) were prepared by the solid state reaction method. X-ray diffraction (XRD) and Rietveld refinement analyses of 1− x (BNT)– x (BZT) solid solution ceramic were employed to study the structure of these systems. A morphotropic phase boundary (MPB) between rhombohedral and cubic structures occured at the composition x =0.05. Raman spectroscopy exhibited a splitting of the (TO 3 ) mode at x =0.05 and confirmed the presence of MPB region. Scanning electron microcopy (SEM) images showed a change in the grain shape with the increase of BZT into the BNT matrix lattice. The temperature dependent dielectric study showed a gradual increase in dielectric constant up to x =0.05 and then decrease with further increase in BZT content. Maximum coercive field, remanent polarization and high piezoelectric constant were observed at x =0.05. Both the structural and electrical properties show that the solid solution has an MPB around x =0.05.