Rayleigh behavior in the lead free piezoelectric li _x(na _0.5k _0.5) _1-xnbo ₃ ceramic

The nonlinear behavior of piezoelectric response in Lix (Li _x(Na _0.5K _0.5) _1-xNbO ₃ ceramics with x = 0:00-0:08 was investigated by Rayleigh analysis. These ceramics exhibited a linear dependence of the piezoelectric coefficient, d ₃₃, with the applied electric field. This data was then analyzed in accordance to the Rayleigh model for poled ceramic materials. The intrinsic contribution was found to be maximized at x = 0:06, where this system has a polymorphic phase boundary at room temperature. The extrinsic contribution, which is the origin of the nonlinearity of piezoelectric response, had a maximum value at x = 0:03-0:04 and is considered to be strongly affected by the crystal symmetry and domain structures.