IMPROVEMENTS TO PYROELECTRIC CERAMICS VIA STRONTIUM DOPING OF THE LEAD ZIRCONATE-LEAD IRON NIOBATE-LEAD TITANATE SYSTEM

Pyroelectric ceramics with the starting composition:[formula omitted] where a is in the range 0-8, were fabricated via the hot-pressing of mixed oxide powders. With increasing values of a, it was found that the Curie temperature decreased and the room temperature dielectric constant (ϵ,) and pyroelectric coefficient p(T) increased. The figure of merit FD, which maximises detectivity, had a peak value of 6.0 x 10 5Pa 1/2 when α = 4. This composition had a dielectric loss, er and p(T) values of 0.28%, 398 and 4.9 x 10-4 Cm 2K-1 respectively at room temperature and 1592 Hz, with a minimum in loss at 5 x 103 Hz. The grain size of these ceramics was found to be highly dependent on the level of Sr substitution; for a values greater than 2, a coarse (12 (μm) grain structure was observed at the edges of the ceramic wafers and this gradually decreased to a grain size of 5 μm in the centre. Possible causes for this microstructural effect are discussed. The ferroelectric domain structures for these ceramics in the unpoled, partially poled and fully poled states are also reported. © 1991, Taylor & Francis Group, LLC. All rights reserved.