Dielectric and electromechanical properties of chemically modified PMN-PT-BT ceramics

A particulate coating process incorporating small amounts of several additives such as titanium, zinc, barium, strontium and iron was used to modify the composition and resultant dielectric and electromechanical properties of a commercially available 0.96(0.91Pb(Mg_1/3Nb_2/3)O₃·0.09PbTiO₃)·0.04BaTiO₃ . This method led to intimate mixing of the additives at the nanoscale without an additional ball-mixing process. Low- and high-field characteristics including dielectric properties, induced strain and polarization, and associated hystereses were evaluated for the samples sintered at 1200 °C for 4 h. All properties were found to depend on the chemical additives and temperature. Specifically, the addition of small quantities of titanium and barium tended to increase strain and Q_eff while maintaining a low dielectric constant which is a promising result for room temperature transducer applications. The addition of titanium with zinc or iron raised dielectric constant, strain, and polarization with significant increases in the temperature of maximum permittivity. On the other hand, the electromechanical properties of the samples containing barium or zinc with titanium did not exhibit a transition to piezoelectric behavior at the temperature expected from the dielectric measurements.