Effect of net PbO content on mechanical and electromechanical properties of lead zirconate titanate ceramics

The effect of net PbO content (obtained by taking into account the amount o f excess PbO added and PbO loss during sintering) on the mechanical and pie zoelectric properties of lead zirconate titanate (PZT) ceramics has been st udied. The samples were prepared by the solid state route using the morphot ropic phase boundary composition Pb(Zr0.5358Ti0.465)O-3. Excess PbO was als o added to the samples in varying amounts from 0-1.0 wt.%. To vary PbO vola tility the samples were sintered with and without a PbO rich atmosphere at 1220 degrees C for 2 h. The resulting Pb content as given by x in Ph1 + x(Z r0.535Ti0.465)O-3 (+ x) varied from.x = -1.7 x O-3 to 1.8 x 10 (-2). The si ntered density was found to increase with increasing lead content. The prec ipitation of the second phase believed to be ZrO2, is observed for x = - 1. 7 x 10(-2). The fracture mode changed from intergranular to transgranular w ith increasing x. The fracture toughness (K-IC) and strength are minimum ne ar x = 0 and increase with increasing as well as decreasing x. The maximum values of ii;, and strength are 1.45 MPa m(1/2) and 90 MPa, respectively, f or x = 1.8 x 10(-3). The dielectric constant and piezoelectric strain coeff icient d(33), increased with x. (C) 1999 Published by Elsevier Science S.A. All rights reserved.