Design of spatially varying electrical poling for enhanced piezoelectricity in Pb(Mg_1/3Nb_2/3)O₃–0.35PbTiO₃

Improvement in operating characteristics of piezoelectric materials, one of the most extensively used dielectric materials, is a major focus of research among materials scientists. Present work puts forward, a novel approach for achieving enhanced piezoelectricity in ferroelectric materials by manipulating electrode placement during poling. Three unique poling configurations, abbreviated as PC1, PC2, and PC3 are developed for exploiting the dependence of effective piezoelectric properties on spatially varying poling direction. Finite element method based numerical simulations are performed to evaluate the electric field distribution, poling direction, and their effect on effective piezoelectric coupling coefficients of PMN–0.35PT (Pb(Mg_1/3Nb_2/3)O₃–0.35PbTiO₃) piezoelectric ceramic. A two-phase solution process is developed to evaluate the local orientation of dipoles for each poling configuration and subsequently computing effective piezoelectric properties of the material in an average sense. Parametric studies are carried out to analyze the effect of aspect ratio R of sample and electrode to sample length ratio, r on effective piezoelectric properties. PC1 yields an increase of up to 135% in the magnitude of the transverse coupling coefficient (e31eff) and an 8% increase in effective longitudinal coupling coefficient (e33eff) while PC2 is observed to exhibit a maximum enhancement of 164% in the magnitude of e31eff and 11.2% in the magnitude of e33eff. PC3, presented as a special case, yields zero values of piezoelectric coefficients in an average sense but can result in a highly elevated net output for bending applications, owing to favorable spatial variation in stresses and associated piezoelectric coefficients.