Electric field induced anisotropy in electrostrictive Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals

The electrostrictive behavior in single crystals of Pb(Mg1/3Nb2/3)O-3 (PMN) and 0.93Pb(Mg1/3Nb2/3)O-3 - 0.07PbTiO(3)(PMN-7%PT) was investigated as a function of crystallographic direction. The pseudocubic nature of these materials became highly anisotropic at relatively high electric fields. The observed anisotropy was believed to be associated with an electric field induced rhombohedral symmetry. Strain values were found to be larger for (001) oriented crystals though larger polarization values were measured in (111) oriented crystals, a consequence of larger electrostrictive coefficients (Q(ij)). The electrostrictive coefficient Q(ij) of the induced phase was found to be independent of composition. Though the crystals exhibited a high degree of anisotropy, no apparent improvement in induced polarization or strain was found when compared with polycrystalline counterparts.