Micro-structural, dielectric, ferroelectric and piezoelectric properties of mechanically processed (Pb_1−xLa_x)(Zr_0.60Ti_0.40)O₃ ceramics

In this work, (Pb_1−xLa_x)(Zr_0.60Ti_0.40)O₃ (PLZT x/60/40, x = at.%) ceramics were prepared by using high energy mechanical ball milling followed by cold isostatic pressing (CIP), investigated for their micro-structural, dielectirc, ferroelectric and piezoelectric properties. Mechanical activation results in the highly reactive nature of the nano size milled PLZT powders, which enables the partial perovskite phase formation, confirmed by room temperature XRD patterns. CIP leads to a higher density with a closely packed dense microstructure of sintered PLZT ceramics shown in SEM images. The grain size of PLZT x/60/40 ceramics was found to be decreasing with increasing La³⁺ content. The highest relative density of ~ 97% was found to be for PLZT 8/60/40 ceramics with grain size of ~ 1.35 µm. The PLZT 8/60/40 system also shows the highest dielectric constant of ~ 1976, remnant polarization of 29.1 µC/cm², piezoelectric coefficients (d₃₃ \(~ \cong ~\) 570 pC/N, g₃₃ \(~ \cong ~\) 28.03 × 10⁻³ Vm/N) and electromechanical coupling factors (k_p = k₃₃ = 64.1% and k₃₁ = 54%). The elastic compliances for the PLZT x/60/40 ceramics were also obtained.