Effects of orientation and composition on the extrinsic contributions to the dielectric response of relaxor-ferroelectric single crystals

The dielectric response of (1-x)Pb(Zn1/3Nb2/3)O-3-xPbTiO(3) (PZN-x% PT, 4.5 <= x <= 12) single crystals is reported for ac field amplitudes up to similar to 2 kV/cm at 1 kHz. The Rayleigh law is used to study the dielectric nonlinear response. It is found that the extrinsic contributions are extremely anisotropic. Rhombohedral crystals poled along [001](C) showed enhanced extrinsic contributions to their dielectric response with respect to those poled along [111](C), while in tetragonal crystals, the enhancement was observed for poling along [111](C) rather than along [001](C). This is attributed to domain engineering or higher domain wall concentrations in ferroelectric crystals poled along nonpolar axes. (C) 2009 American Institute of Physics. [doi:10.1063/1.3245316]