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 Bri llouin spectroscopy using a new experimental configuration. Amorphous films deposited on platinized substrates were treated at temperatures between 35 0 and 650 degrees C, using rapid thermal annealing. A variation of the soun d velocity in the films with the annealing temperature was measured. A clea r decrease at 375 degrees C and a continuous softening of the sound velocit y up to 475 degrees C were observed. The latter is followed by a jump towar d higher values of the sound velocity when the samples are treated at highe r temperatures. Grazing incidence x-ray diffraction and profilemetry have b een used to monitor structural changes and variation of film thickness with temperature, inferring relations among these parameters and properties obt ained from the Brillouin measurements. (C) 1999 American Institute of Physi cs. [S0021-8979(99)06610-4].