Highly dense and crack free 50-μm-Thick PZN-PZT films by aerosol deposition method

Lead zinc niobate -lead zirconate titanate (PZN-PZT) thick films with thickness of ~50 μm were deposited on silicon and alumina substrates using aerosol deposition method (ADM). The effects of excess lead oxide (PbO) on stress relaxation during post-annealing were studied. Excess PbO content was varied from 0 to 5 mol%. The as-deposited film had fairly dense microstructure with nano-sized grains. The as-deposited films on on sapphire were annealed at 900degC in an electrical furnace. The annealed film was detached and cracks were generated due to the high residual compressive stress and thermal stress induced by thermal expansion coefficient mismatch. However, the film deposited using powder containing 2% of excess PbO showed no cracking or detachment from the substrate after the post-annealing process. The PbO evaporation at elevated temperature during the post-annealing process seemed to have reduced the residual compressive stress. The remanent polarization and relative dielectric constant of the 50 μm-thick films annealed at 900°C were 43.1 C/cm and 1400, respectively, which were comparable with the values of a bulk specimen prepared by powder sintering process.