Dielectric and piezoelectric properties of rare-earth gadolinium modified lead lanthanum zirconium niobium titanate ceramics

This paper reports the dielectric and piezoelectric properties of rare-earth Gd modified PLZNT solid solutions with a stoichiometric formula [Pb(0.988−x)La0.012Gdx][(Zr0.53Ti0.47)(0.972−(x/4))Nb0.02O3] (hereafter known as PLGZNT) with x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol% synthesized through solid state reaction method for phase formation, microstructure, dielectric and piezoelectric properties. The powder X-ray diffraction results obtained for PLGZNT ceramics showed pure perovskite phase with tetragonal symmetry sintered at 1245 °C supported by an accurate structure analysis of tolerance factor (t) and averaged electronegativity difference (e). The scanning electron micrograph showed pore-free homogeneous nature of grains which could be ascribed to a denser ceramics having enhanced distribution of grain orientations. It is observed that increasing Gd content in the lattice influenced the dielectric and piezoelectric properties. The optimum dielectric (ɛRT and tan δ) and piezoelectric properties (d33 and kp) were observed in 0.6 mol% Gd modified PLZNT ceramic composition which attained saturation and thereafter decreased.