Nonlinear Piezoelectric Coefficients in Compositions near Morphotropic Phase Boundary of PbZrO_3-PbTiO_3-Pb(Mg_(1/3)Nb_(2/3))O_3 Piezoelectric Ceramics

摘要

Linear and nonlinear piezoelectric coefficients of second- and third-higher terms in length-extensional vibration were experimentally investigated in the compositions near the morphotropic phase boundary (MPB) of PbZrO_3-PbTiO_3-Pb(Mg_(1/3)Nb_(2/3))O_3 ternary piezoelectric ceramics. The Zr/Ti ratio showing the maximum value of the piezoelectric constant d_(31) disagreed with that showing the maximum value of the electromechanical coefficient k_(31) in the transverse vibration. The disagreement increased with Pb(Mg_(1/3)Nb_(2/3))O_3 (PMN) content. The nonlinear piezoelectric coefficients of the second- and third-higher terms showed their minimum values at the Zr/Ti ratios showing the maximum values of d_(31). Hence, the Zr/Ti ratio showing the maximum value of d_(31) was regarded as the MPB composition. The nonlinear coefficients of the second- and third-higher terms on the MPB compositions showed different dependences on PMN content. The nonlinear coefficient of the second-higher term showed a grain size dependence in its change, and that of the third-higher term showed a mechanical quality factor dependence in its change. The difference in the dependences was discussed from the viewpoint of the difference in the occurrence mechanism of nonlinear phenomena dominating the two nonlinear coefficients.