Effects of Seeding Layer on Perovskite Transformation, Microstructure and Transmittance of Sol-Gel-Processed Lanthanum-Modified Lead Zirconate Titanate Films

Abstract

A series of sol-gel-processed lanthanum-modified lead zirconate titanate (PLZT) thin films with La/Zr/Ti ratios of 8.5/65/35, 9/65/35, 9.5/65/35, 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 temperatures from 475° C to 685° 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 higher Ti/Zr ratio show lower transformation (from pyrochlore to perovskite) temperature. The PLZT(8.5–9.5/65/35) thin film with the seeding layer shows improved phase content, high optical transmittance and enhanced perovskite transformation kinetics. The grain sizes are reduced (from 5–6 µ m to 0.1–0.2 µ 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 enhanced, and the polarization value at 400 KV/cm increases for the film with the seeding layer.