Dielectric properties of La-modified antiferroelectric PbZrO₃ thin films

Abstract

Lead zirconate is a room temperature antiferroelectric material, which exhibits double polarization hysteresis characteristic in the presence of external field. A transformation from antiferroelectric to paraelectric behavior through a ferroelectric phase has been exhibited upon addition of La-to pure lead zirconate thin films, which were confirmed from dielectric, hysteresis and pyroelectric and micro Raman analyses. Thin films of pure and La-modified lead zirconate were processed using A-site vacancy formula Pb_(l-1.5x)La_XZrO₃ by pulsed excimer laser ablation technique. Pyroelectric coefficient increased gradually from 55 to 190 µC cm^-2 K^-1 with the addition of 0 to 9 mole% of La to pure lead zirconate. The transition temperature has been reduced to room temperature (~34 °C) with addition of a 9 mole% of La-to lead zirconate. Presence of antiferroelectricity in pure lead zirconate thin films is due to antiparallel shifts of Pb-ions in (110) direction and reduction of transition temperature is attributed to creation of A-site vacancies would have caused enhancing of ferro-and paraelectric behavior with La-addition.