Composition dependence of piezoelectric constant and dielectric constant tunability in the -oriented Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals

Composition dependence of room temperature piezoelectric constant d33 and dielectric constant tunability was investigated in the 〈001〉-poled single crystals of (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 with x varying from 0.24 to 0.38. Temperature, frequency and composition dependence of the dielectric constant in the unpoled crystals shows that the critical composition for the relaxor state lies in the 0.69Pb(Mg1/3Nb2/3)O3–0.31PbTiO3 crystal. It has also the largest piezoelectric constant d33 of 2210 pC/N and highest dielectric constant tunability of 40.6% (at a dc bias of 1000 V/mm). The experiment results validate the prediction that the relaxor-based materials with the critical composition for the relaxor state will have the highest piezoelectric susceptibility.