Role of strain and lattice distortion on ferroelectric and piezoelectric properties of bismuth magnesium zirconate substituted sodium bismuth titanate ceramics

Effect of weak ferroelectric perovskite, bismuth magnesium zirconate [Bi(Mg0.5Zr0.5)O-3] substitution in lead-free sodium bismuth titanate [(Na0.5Bi0.5)TiO3] ceramics is studied. Influence of substitution on intrinsic and extrinsic contribution and impact on ferroelectric and piezoelectric properties are investigated. Improved spontaneous polarization (P-s), increased remnant polarization (P-r), decreased coercive field (E-c) and high piezoelectric coefficient (d(33)) are obtained for x = 0.01 mole fraction of Bi(Mg0.5Zr0.5)O-3 substitution due to decrease in rhombohedral lattice distortion and homogeneous strain. Small rhombohedral lattice distortion (delta(r)) and minimum homogeneous strain (delta) are the primary intrinsic parameters which favours the extrinsic parameters such as mobility of non-180A degrees domain reorientation, domain switching and domain wall motion. Enhanced mobility softens the coercive field and increases remnant polarization to maximum. Reduced rhombohedral lattice distortion, low strain and enhanced mobility are the key factors for enhanced piezoelectric constant, highest remnant polarization and decreased coercive field in non-MPB (1 - x)(Na0.5Bi0.5)TiO3-xBi(Mg0.5Zr0.5)O-3 solid solutions.