Temperature dependence of electromechanical properties of PLZT <Emphasis Type="Italic">x</Emphasis>/57/43 ceramics

The compositions of lead lanthanum zirconate titanate PLZT Pb(Zr_0.57Ti_0.43)O₃ + x at% of La, where x = 3, 5, 6, 10 and 12] have been synthesized using mixed oxide route. The temperature dependent electromechanical parameters have been determined using vector impedance spectroscopy (VIS). The charge constant d ₃₁ and elastic compliance s ₁₁ ^E show a peak in all the samples at a temperature T _mt much below the ferroelectric — paraelectric transition temperature, whereas the series resonance frequency f _s shows a dip at these temperatures. The Poisson’s ratio σ ^E increases with temperature T showing a broad peak at a temperature higher than T _mt . The voltage constant g ₃₁ decreases and the planar coupling coefficient K _p remains constant up to half of the T _mt and then falls sharply with T. Half of the T _mt can, therefore, be used for specifying the working temperature limit of the piezoceramics for the device applications.