Structural and electrical properties of (1−x)(Na0.5Bi0.5)TiO3–xBi(Mg0.5Zr0.5)O3 lead-free piezoelectric ceramics

Sodium bismuth titanate–bismuth magnesium zirconate (NBT–BMZ) lead-free piezoelectric ceramics are synthesized by a solid-state reaction method up to x=0.04 mole fraction. Effect of substitution on dielectric, ferroelectric and piezoelectric properties is studied in relation with structure and morphology. Rhombohedral R3c structure symmetry is maintained up to x=0.025 mole fraction. Higher mole fraction of bismuth magnesium zirconate substitution prompts phase transition from rhombohedral to higher symmetry cubic phase. Morphology and homogeneity of grains changes on BMZ substitution. Minimum homogeneous strain and small rhombohedral lattice distortion influences the extrinsic contribution for improved dielectric constant, remnant polarization and piezoelectric coefficient. Enhanced mobility and domain reorientation softens coercive field and increases remnant polarization and piezoelectric coefficient to maximum at x=0.01 mole fraction of BMZ substitution. Decrease in dielectric, ferroelectric and piezoelectric properties are due to structure change to cubic phase on higher mole fraction of BMZ substitution.