Structure and properties of antiferroelectric PLZST ceramics prepared by solid state synthesis

Abstract

This formal report is an account of the author’s Final Year Project focusing on antiferroelectric lanthanum-doped lead zirconate titanate stannate (PLZST) ceramics with tetragonal perovskite structure.

Antiferroelectric (Pb,La)(Zr,Ti,Sn)O3 (PLZST) ceramics with compositions close to the morphotropic phase boundary (MPB) between ferroelectric (FE) rhombohedral and antiferroelectric (AFE) tetragonal phases have attracted a lot of attention due to their low switching field and large electric-field-induced strain. Due to their proximity to the MPB, they possess a relatively small free energy difference between the two phases compared to those located further away, and this allows the application of a small external electric field to switch the material between the two phases easily. Such a phenomenon has applications for shape memory devices, high strain actuators and so on.

This study includes the preparation of 4 compositions of AFE tetragonal PLZST ceramics with low switching field and large strain, using conventional mixed oxide ceramic processing techniques. The fabricated ceramics were characterized using a range of techniques that include XRD, SEM, dielectric, ferroelectric and electric-field-induced strain measurements. Small switching field of 13.7 kV/cm and large strain of 0.34% were achieved with the composition (Pb0.97La0.02)(Zr0.66Sn0.235Ti0.105)O3, with densities of 7.7-8.0 g/cm3. Dielectric constant and loss of around 1000 and 0.02% respectively were recorded.