Abstract:
A-site off-stoichiometry has been an efficient method to enhance the elec tromechanical properties of lead-free Na0.5Bi0.5TiO3(NBT)-based piezoceramics.
In this work, we have reported the effect of Na/Bi off-stoichiometry on the
microstructural, structural, and electromechanical properties of the tetragonal
0.80Na0.5Bi0.5TiO3–0.20BaTiO3 (NBT–20BT) ceramic. The maximum piezore sponse * 115 pC/N is obtained for 4 mol% Na-deficient (20BT–Na46) and
2 mol% Bi-excess (20BT–Bi52) compositions. It is a 25% increment over the
piezoresponse of the stoichiometric composition (20BT–Na50 * 90 pC/N). The
enhancement in piezoresponse has been attributed to an optimized presence of
polar-structural heterogeneity/disorder in the poled ceramic matrix and an
optimized distortion of the long-range tetragonal ferroelectric phase. It is
established that A-site off-stoichiometry is influencing the polar-structural
heterogeneity/disorder and tetragonal lattice distortion via the grain size.
