COMPLEX PIEZOELECTRIC, ELASTIC, AND DIELECTRIC COEFFICIENTS OF LA-DOPED 0.93 PB(MG1/3NB2/3)O3-0.07 PBTIO3 UNDER DC BIAS

Complex material parameters (piezoelectric coefficient d31 elastic s11E, and the dielectric constant K33) of the relaxor ferroelectric ceramic (1-x) Pb(Mg1/3Nb2/3)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. © 1990, Taylor & Francis Group, LLC. All rights reserved.