Research On The Preparing Process And Properties Of PZT Ceramics

A new method (wet-dry method) for preparing PZT powder and ceramics is proposed. The effect of the composition, sintering condition of powder, forming pressure, sintering temperarure and soaking time of ceramic on dielectric and piezoelectric was investigated. Small amout of Nb⁵⁺ was then added to this system as adoping to improve the properties.First, B-site precursor of perovskite PZT was prepared via the chemical wet method. The precursor is Zr_xTi_1-xO₂ solid solution of single phase with ZrTiO₄ structure from XRD. The composition range (x=0.50⁰.56) exceeds the limit of that of conventional solid solution method. Second, PZT powder was formed from solid reaction(wet) between this B-site precursor and PbCO3. XRD, SEM, ESCA and Sedimentograph was also applied to identify the powder. It was found that the optimum calcinations condition of perovskite-phase was above 750℃. The average diameter of the PZT powder was 113 nm and Morphotropic Phase Boundary (MPB) was at x =0.52～0.54.The sintering characteristics were studied after moulding. Through analyzing effect on electric properties of PZT ceramic made by forming pressure, sintering temperature and soaking time, it was identified that compact ceramic could be obtained at forming pressure of 200 MPa, sintering temperature of 1200℃and soaking time of 2 h. The highest volume density 7.80 g/cm³ and electric propertiesε_r=1268,d₃₃=328 pc/N,K_p=0.615 could be got at x=0.52.In order to improve the electric properties of PZT ceramic and decrease the sintering temperature, Nb⁵⁺ was added to the ceramic. The results revealed that the electric properties of the ceramic were enhancedε_r=1397,K_p=0.647,d₃₃=389 pc/N by adding 0.02 mol% Nb⁵⁺.