Thermal induced changes of lead zirconium titanate films and their consequences for liquid crystal devices applications

Abstract

Thin films of lead zirconate titanate (PZT) were obtained by a modified sol–gel route on float glass and indium tin oxide (ITO)-covered float glass substrates. Different thermal treatments were performed on the deposited films in the temperature range 100–700°C. Spectroscopic ellipsometry was used to investigate the optical properties of the deposited films, and the changing optical absorption spectra were interpreted in terms of the growth of two different crystal phases, pyrochlore and ferroelectric perovskite, as a function of annealing temperature. Moreover, a specific resonance at 1.9 nm was detected when thin PZT films are deposited on ITO substrates and was attributed to a particular charge distribution at the interface. Finally, the performance in rectifying the electro-optical response of asymmetric nematic liquid crystal cells was tested for some of the films undergoing different thermal treatments.

Keywords:

• lead zirconium titanate thin films
• sol–gel technique
• structural properties
• optical properties
• thermal treatments

Acknowledgements

The authors wish to thank Dr Giuseppe De Santo and Dr Tiziana Barone for their essential contribution during the PZT thin layers preparation.