Soft Chemistry Synthesis Of Lead Zirconate Titanate Piezoceramics Powders And Films

Lead zirconate titanate piezoceramics, which are characterized by remarkable dielectric,piezoelectric, ferroelectric and pyroelectric properties, are widely used in many components includingsensors, actuators and transducers. Because of the characteristics of high sensitivity and output strain,PZT is becoming a promising material for micro-electro-mechanical systems (MEMS) in recent years.So the synthesis of PZT powders and films with high quality has become an important part in the fieldof piezoceramics. In this research, we try to synthesis PZT powders and films by combining sol-gel,hydrothermal and solvothermal method. The major subject research and results are given asfollowing:(1) A novel sol–hydrothermal/solvothermal method has been used to synthesize PZT powders.We used isopropyl alcohol (IPA) as the solvent for solvothermal method. The effects of differentparameters including KOH concentration, IPA/(IPA+water) ratio and reaction temperature, on themicrostructures of the PZT powder were studied. With increasing KOH concentration and reactiontemperature, the crystalline structure of as-synthesized PZT transformed from tetragonal torhombohedral phase. More IPA added in the solvent can effectively reduce agglomeration of the PZTpowder and decrease the crystallization temperature, but impurity phase was also detected at highIPA/(IPA+water) ratio. As a result, the synthesis parameters are optimized, and well-crystallized700nm PZT particles were successfully synthesized in2.0M KOH and50%IPA/(IPA+water) ratio attemperatures as low as120°C.(2)The effect of hydrothermal treatment of substrate on the synthesis of PZT films has beenstudied. The Si substrates were hydrothermally treated at200oC for different hours to be changed intoSiO2/Si substrates. The hydrothermal treatment of substrate has considerably improved the film’sperformance; The PZT thin films crystallize better and become more compact with the increase ofannealing temperature and hydrothermal reaction time; The film hydrothermally treated at200oC for16h and then annealed at850oC shows the best crystallization property and surface morphology; Thethickness of the films varied from1μm to2μm with the increase of layer number.(3)Hydrothermal crystallization treatment was used to take place the high temperature annealingin traditional sol-gel method to prepare PZT thin films. The suitable condition for hydrothermalcrystallization treatment is180-220°C with1M KOH concentration. The reaction medium has a greatimpact on the phase and composition of PZT films. The Zr/Ti ratio in PZT films changed with thechange of Zr/Ti ratio in the reaction medium. When the reaction medium has a Zr/Ti ratio of68:32, the Zr/Ti ratio of PZT film is closest to52:48.When the Hydrothermal medium contains only lead andzirconium source (labeled PZ), the sample obtained at early time is PbO, and then it changed intoperovskite structure. With the time going on, the sample changed from Ti-rich to Zr-rich. And at80min, the sample’s Zr/Ti ratio is closest to52:48. PZT film synthesized using this method has adense and uniform surface morphology.