Structural, dielectric and electromechanical properties of Cr-doped PLZT close to the morphotropic phase boundary region

Piezoelectric ceramic lead lanthanum zirconate titanate (PLZT), doped with Cr2O3 [Pb(Zr0.57Ti0.43)O-3 + 6 at% La + x mole% Cr2O3, x = 0, 0.05, 0.11, 0.16, 0.22, 0.54 and 1.08], has been prepared by the solid-state reaction method, and characterized by X-ray diffiractometry, scanning electron microscopy, vector impedance spectroscopy (VIS). The VIS studies reveal the donor-like role of Cr for x < 0.16 mole%, and acceptor-like role for higher doping concentrations. Maxima of coupling coefficient K-p, charge constants d(33), d(31), d(h) and dielectric constant epsilon(T)(33) are observed at x = 0.05 mole%, at which concentration Cr behaves as a donor. The average value of Poisson's ratio, a E, is found to be 0.34 +/- 0.01, with a slight decrease in values x > 0.16 mole%.