Soft Chemistry Synthesis Of Lead Zirconate Titanate Piezoceramics Powders

Lead zirconate titanate piezoceramics, which are characterized byremarkable dielectric, ferroelectric and piezoelectric properties, are widely usedin many components including sensors, actuators and transducers. Therefore,the research of PZT piezoceramics with high performance has greatsignificance. The performance of the piezoelectric ceramics is directly affectedby the quality of the ceramic powders. PZT ultra-fine powders with theadvantages of smaller particle size, larger specific surface area and higherpowder reaction reactivity, have been focused in the PZT ceramics area. Themajor subject research and results are given as following:(1) We have successfully synthesized PZT powders with single-phase,sphere morphology and an average size of100nm using sol-gel method. Theexcess Pb has important influence on the the sythesis process and the PZTproduct. Experiments proved if the content of the excess Pb is too little or toomuch, it can not promote the crystallization of the PZT powders. Moreover,3％excess Pb, wich is the appropriate excess Pb, is noted to greatly acceleratethe transformation to perovskite and obviously decrease the reactiontemperature of the phase pure PZT. The reaction temperature of the phase purePZT can be effectively decreased by prolonging the calcination time. As thecalcination temperature increases, the crystallinity is improved gradually.Especially when the calcination temperature is above700℃, the crystallinitycan be obviously improved.(2) The phase pure PZT powders with sphere morphology and an averagesize of150nm are synthesized at430℃by the modified sol-gel method usingdiethanolamine (DEA) as the polymerizing agent to assist the sol-gel process.When the content of DEA is10％, the transformation to perovskite can beaccelerated obviously and the phase pure PZT nanoparticles can besynthesized at a relatively low temperature of430℃.(3) A novel sol-hydrothermal route, which combines the sol-gel andhydrothermal methods, is used to prepare PZT fine particles. The phase purePZT powders are synthesized at150℃. When synthesizing the PZT powders using the sol-hydrothermal process, the experimental parameters, shuch assol/(sol+water) ratio, reaction temperature and reaction time, have theoptimum values. The preparation of the pase pure PZT powders will beaffected if these values are too little or too much. The well-crystalline phasepure PZT products with homogeneous cubic-shaped morphology and anaverage size of700nm are synthesized at20％excess Pb, sol/(sol+water)=20％, KOH concentration of1M, reacting at200oC for8h.