Haitao Huang, Jayati Ray and Peter Hing

Advance Materials Research Center, School of Applied Science, NTU, Singapore

Perovskite ferroelectric materials are now widely used in infrared sensors instead of the conventional semiconductor sensors due to their wide range of response frequency, quick response and easy operation at room temperature. The most commonly used material for infrared sensors are lead zirconate titanate (PZT) based ceramics, BaTiO₃. Although this kind of sensors has already been commercialized, the properties of these sensors are far from perfect. To achieve high quality sensor it is necessary to produce fine and homogeneous powders. The conventional solid-state reaction method requires very high temperature, but still the product is not crystalline and the product obtained by this method consists of non-uniformity and coarse type. In order to solve this problem sol-gel method is most useful to prepare homogeneous, nano-sized powders at low temperature. Small amount of SiO2 increases the mechanical strength of the commercialized pyroelectric sensor materials. The fracture mode of the ceramics changes from mainly intergranular to mainly transgranular. Pyrochlore phase is not detectable from XRD results. The grain boundary is thin and the glass phase is located at the triple points of the grains. A-site substitution of calcium decreases both the dielectric constant and pyroelectric coefficient of PZT 94/6 ceramics. A small amount the calcium can improve the figure of merit which is mostly concerned in devices.