Pyro, Ferro and Dielectric Properties of Ba0.8 Sr0.2TiO3 Films Deposited by Sol-Gel on Platinized Silicon Substrates
Résumé
We report on the deposition by a sol-gel process of Ba0.8 Sr0.2TiO3 films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 102<:sup> to 106 Hz decreases slightly and is around 400 at 104 Hz. The losses are constant in a first approximation for a 1.5 μ m thick film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained at 293 K and 10 kHz is 40 μ C/m3 /K