Complex piezoelectric, elastic, and dielectric coefficients of La-DOPED 0.93 Pb(Mg_1/3Nb_2/3)O₃:0.07 PbTiO₃ under DC bias

Abstract

Complex material parameters (piezoelectric coefficient d₃₁, elastic s₁₁ ^E, and the dielectric constant K₃₃) of the relaxor ferroelectric ceramic (1−x) Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃(x =.07) with 1% La (lanthanum) were measured as a function of bias field using a bar resonator. The values of the dielectric and piezoelectric phase angles are found to be comparable (i.e., around 0.04 for a d.c. bias field of 2.5 kV/cm), while the elastic phase angle is an order of magnitude smaller (0.001 for the same d.c. bias). For comparison of complex material parameters found from bar resonators, a sample in the form of a small disk is used to measure Poisson's ratio as well as the real components of the piezoelectric and elastic coefficients as a function of bias field.