PROCESSING AND FERROELECTRIC PROPERTIES OF Pb0.91Sr0.09(Zr0.53Ti0.47)O3 CERAMICS

Abstract

Lead Zirconate Titanate (PZT) with formulae Pb0.91Sr0.09(Zr0.53 Ti0.47)O3 was prepared by conventional mixed oxide route with an objective to achieve dense piezoelectric sintered components exhibiting adequate properties for sonar applications. Dielectric and ferroelectric/piezoelectric properties of PZT are strongly influenced by composition, homogeneity and porosity in the densified part. To achieve the objective of a good homogenous and dense body, the initial powders and the final product were characterized by SEM equipped with EDX, XRD and Particle Size Analyzer during each processing step. Electrical characterization was carried out by LCR meter and Transducer Analyzer. Planetary Mill instead of a conventional ball mill was employed for initial mixing and grinding of calcined powder. Properties achieved by sintering at 1200°C for 2 hours in lead rich atmosphere were Dielectric Cosntant (K) = 1440, Tangent Loss (Tanδ) = 0.0062, Charge Coefficient(d33) = 335 pC/N, Coupling Coefficient (k) = 0.37 and density = 7.55 g/cm3 . XRD analysis of calcined powders showed that excess PbO added at the time of preparation of the mixture started to evaporate at the calcination stage. After sintering the observed grain size was 2-3 µm with clean grain boundaries. To ascertain the effects of accelerated ageing on dielectric and piezoelectric properties, final product was first heated at 50°C for 5 days and then at 100°C for 3 days. The results showed that dielectric and piezoelectric properties were stabilized to a large extent by heating at 100°C for 3 days. The ageing data for 9% Sr doped PZT is not reported earlier, therefore, it would help in great deal in predicting the performance of component in service.