Effect of Drying Temperature on Phase Transformation, Electric Prperties of Sol-Gel Derived Lead Zirconate Titanate Powders and Ceramics

Abstract

Lead zirconate titanate (PZT) (53/47) powders and ceramics were successfully prepared using a cheating acetate sol-gel process. The electropositive nature of titanium, zirconium and the presence of highly polar M-O (M means titanium or zirconium) bonds means that titanium and zirconium alkoxides are extremely reactive towards water. In this study, acetic acid really plays an important role, which acts as a chemical modifier or chelating agent, on the preparation of the solution. Phase characterization of the lead zirconate titanate (PZT) material was performed by X-ray diffraction analysis (XRD). Microstructure of the powders was examined by transmission electron microscopy (TEM). The XRD pattern showed that well-crystallized, sub-micrometer-sized, phase co-existing, the perovskite PZT powders were obtained after drying PZT stock solution at 300°C for 30 min, followed by a heat treatment at 900°C for 4 hr. TEM figure showed the aggregation of 20–30 nm sized particles which matched with the calculated result from XRD. The chemical homogeneity and composition control of PZT powders (Zr/Ti mole ratio is 53/47) was examined using TEM-EDS analysis. XRD patterns of sintered bulk ceramics also pointed out the coexistence of the tetragonal and rhombohedral phase with no impurity phase as pyrochlore. Relative densities of these sintered bulk ceramics were as high as ∼ 99%. For the dielectric and piezoelectric properties at room temperature, bulk ceramics sintered at 1100°C for 2 hr gave the higher dielectric coefficient ∼ 2863, lower dielectric loss ∼ 0.002, and a Kp value ∼ 0.235. Such a higher density, and better dielectric and piezoelectric properties will enhance the ability of PZT ceramics in SAW devices.