The physics of pyroelectric in frared detectors as it applies to the selection of detector materials is briefly reviewed and the properties ofa number of the more commonly used materials are corqared. The use of ferroelectricsin the region o f the Curie temperature as dielectric bolometers with an applied bias field is assessed and the properties of barium strontium titanate and lead magnesium niobate for use in this mode are reportea and their potential compared with the conventional pyroelectrics.