PZT ceramics from hydrothermally synthesized powders

PZT (PbTi_1-xZr_xO₃, x=0.52 to 0.64) powders were hydrothermally produced at 200°C for 24 hrs, from a solution containing Ti(OH)4·xH₂O, ZrOCl₂, Pb(CH₃COO)_z, and NaOH. PZT (x=0.52) powder was also produced by the solid-state sintering method. The powders from both the hydrothermal method and the solid-state reaction method were pressed and subsequently sintered at 1250°C for 2 hrs. The characteristic difference of the ceramics produced from both powders were compared with each other. The hydrothermal PZT powders are chemically homogeneous, and around 0.2 μm in particle size (numerical average). The solid state reacted powder is a mixture of tetragonal PbTiO₃, rhombohedral PbZrO₃, unreacted TiO_z, and unreacted PbO. The PZT ceramics from hydrothermal powders become softer, i.e., lower Ec and higher Pr, as more Zr_x is added in PZT (higher x value). The K, Q, and Kp values reach maximum when x=0.54. The Q value monotonously increases with the x value and the Kp value likely increase with the grain size of the ceramics. The ceramics from the hydrothermal method have higher density, grain size, dielectric constant, Kp, and lower D and Qm. The hydrothermal powders are much more sinterable than powders produced by the solid-state reaction method