EFFECTS OF SEEDING LAYER ON PEROVSKITE TRANSFORMATION, MICROSTRUCTUREAND TRANSMITTANCE OF SOL-GEL-PROCESSED LANTHANUM-MODIFIED LEAD-ZIRCONATE-TITANATE FILMS

A series of sol-gel-processed lanthanum-modified lead zirconate titana te (PLZT) thin films with La/Zr/Ti ratios of 8.5/65/35, 9/65/35, 9.5/6 5/35, 15.5/40/60 and 18/30/70 were prepared on indium tin oxide (ITO)- coated Corning 7059 glass substrates and heat-treated at different tem peratures from 475 degrees C to 685 degrees C. The X-ray diffraction, microstructure, optical transmittance spectra and the polarization vs electric field curves were investigated. The P(L)ZT thin films of high er Ti/Zr ratio show lower transformation (from pyrochlore to perovskit e) temperature. The PLZT(8.5-9.5/65/35) thin film with the seeding lay er shows improved phase content, high optical transmittance and enhanc ed perovskite transformation kinetics. The grain sizes are reduced (fr om 5-6 mu m to 0.1-0.2 mu m) and uniform. The fracture surfaces of the films with a seeding layer consist of columnar structure of which the grains grew from the seeding layer. The optical transmittance is enha nced, and the polarization value at 400 KV/ cm increases for the film with the seeding layer.