Diffuse phase transition and relaxor behavior in (PbLa)TiO3 thin films

Room-temperature micro-Raman scattering and temperature-dependent dielectric measurements were carried out on sol-gel-derived ferroelectric Pb1-xLaxTi1-x/4O3 (PLT x=0.05-0.30) thin films. Results indicate that the crystal structure and the electrical properties of PLT films were strongly influenced by the La contents. The dielectric properties of PLT thin films were studied in the temperature range of 80-700 K and frequencies in the range of 1 kHz-1 MHz. Results show that PLT thin films undergo normal-to-relaxor ferroelectric transformation with 30 at. % La contents. The observed relaxor behavior is established in terms of diffuse phase transition characteristics and Vogel-Fulcher relationship. (C) 2002 American Institute of Physics.