Patents
The invention relates to a method of making nanosized PZT[Pb(Zro.52Tio.48)O3] powder by a modified citrate-nitrate gel method at a temperature of 500°C. The synthesized powder can be sintered at a temperature in the range of 750-800°C by adding a small amount of sintering aid like LiBiO2. This contrasts to the normally required sintering temperature of 1200-1300°C and hence the process is cost-effective. Also, there is no need to atmosphere control during sintering to contain lead volatilization, as the sintering temperature is low. Above all, the piezoelectric properties of the sintered samples are equivalent or superior to those made by conventional sintering at a high temperature. For example, the sintered PZT pellets made by the invented process followed by poling at 100-130°C under an electric field of 1-3kV/mm showed ε33 in the range of 970-1225, d33 in the range of 230-465 pC/N, g33 in the range of 27-43x10"3 V-m/N, kp in the range of 0.41-0.63, Qm in the range of 23-54, whereas for PZT sintered above 1200°C, the literature reported values areε33 = 730, d33= 223 pC/N, g33 = 34.5 V-m/N, kp= 0.51, Qm= 500 (Qm for the soft PZT formulation is in the range of 60-80). Hence, the PZT ceramics made by the invented method will be cost-effective and can be used for low-power ultrasonics, sensors, pickups, acoustic devices and actuators.