Relaxor-like dielectric behavior of pulsed-laser-deposited Pb0.5Sr0.5TiO3 films

Pb0.5Sr0.5TiO3 (PST) ferroelectric films were deposited onto Pt/Ti/SiO2/Si substrates by pulsed laser deposition. The state of the films can be described as a mixed state, with both ferroelectric and relaxor-like features. The films exhibited high dielectric constant and tunability at room temperature. At 10 kHz, the dielectric constants of the 200-nm- and 400-nm-thick films are 771 and 971, with the tunability of 60.2% and 70.9%, respectively. The temperature-dependent dielectric properties were studied and the relaxor-like behavior was observed in both the thinner and thicker PST films, which can be established in terms of diffuse phase transition characteristics and Vögel-Fulcher relationship. In addition, the contribution of the film-electrode interface layer to the dielectric properties was evaluated and the true dielectric properties of the films were reconstructed. Consequently, the relaxor-like character of the PST films was mainly ascribed to the effect of the film-electrode interfaces.