Effect of La₂O₃ addition on microstructure, morphology and pressure sensing behaviour of PZT based ceramics sintered in Al₂O₃ environment

Effect of La₂O₃ addition on microstructure, morphology and pressure sensing behaviour of (Pb1-x, Lax)(Zr₀.₅₂, Ti₀.₄₈)O₃ based ceramics was studied in three different compositions of La₂O₃, namely x = 0.10, 0.12 and 0.15. The samples were prepared through a conventional solid-state reaction method using high purity metal oxides powders. In order to control the PbO losses due to high sintering temperature, a novel approach was explored whereby the samples were sintered in Al₂O₃ environment. Structural investigation using XRD revealed that all samples exhibited a tetragonal crystal structure. However the c/a ratios exhibited a decreasing trend as the La₂O₃ content increased, indicating that (Pb1-x, Lax)(Zr₀.₅₂, Ti₀.₄₈)O₃ crystals gradually evolved towards pseudocubic structure. SEM micrographs showed that in all samples the grains have uniform pebble stone morphology. The average grain size reduced from ~ 4.5 μm to ~ 3.0 μm with the increment of La₂O₃ content. The performance of pressure sensing behaviour which was investigated using custom-made pressure chamber showed that sample with composition of x = 0.10 exhibited the best piezoelectric properties with high pressure sensitivity, good stability and repeatability.