Preparation of highly dense PZN-PZT thick films by the aerosol deposition method using excess-PbO powder

Lead zinc niobate-lead zirconate titanate thick films with a thickness of 50-100 mu m were deposited on silicon and alumina substrates using the aerosol deposition method. The effects of excess lead oxide (PbO) on stress relaxation during postannealing were studied. Excess PbO content was varied from 0 to 5 mol%. The as-deposited film had a fairly dense microstructure with nanosized grains. The films deposited on silicon were annealed at temperatures of 700 degrees C, and the films deposited on sapphire were annealed at 900 degrees C 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 postannealing process. The PbO evaporation at elevated temperature during the postannealing process seemed to have reduced the residual compressive stress. The remanent polarization and relative dielectric constant of the 50 mu m thick films annealed at 900 degrees C were 43.1 mu C/cm(2) and 1400, respectively, which were comparable with the values of a bulk specimen prepared by a powder sintering process.