Elastic properties by Brillouin spectroscopy of sol-gel (Pb,Ca)TiO3 films

A direct evaluation of elastic properties and refractive indices of sol-gel derived calcium modified lead titanate films has been made by means of Brillouin spectroscopy using a new experimental configuration. Amorphous films deposited on platinized substrates were treated at temperatures between 350 and 650 degrees C, using rapid thermal annealing. A variation of the sound velocity in the films with the annealing temperature was measured. A clear decrease at 375 degrees C and a continuous softening of the sound velocity up to 475 degrees C were observed. The latter is followed by a jump toward higher values of the sound velocity when the samples are treated at higher temperatures. Grazing incidence x-ray diffraction and profilemetry have been used to monitor structural changes and variation of film thickness with temperature, inferring relations among these parameters and properties obtained from the Brillouin measurements. (C) 1999 American Institute of Physics. [S0021-8979(99)06610-4].