Modified lead scandium tantalate for uncooled LWIR detection and thermal imaging

Lead scandium tantalate (PST) has been shown to have exceptionally good pyroelectric figures of merit, especially for small detectors of the type involved in the large arrays needed for uncooled solid-state thermal imaging. The authors review the properties of PST in relation to those of other materials which have been considered for use in this role and discuss how dopants, including K/Bi, Nb, Ti, and Zr, can be used to modify the properties of the material in a way which would be beneficial to certain modes of detector operation, particularly with respect to the elimination of the requirement for cooling. F_D figures-of-merit of over 20×10^-5 Pa^-1/2 are reported. The results of measurements of the properties of PST after aging under high fields are presented. The major observed change is in that dielectric loss increases gradually due to a thermally activated process, showing an increase of about 20% after 5000 h at 100°C, corresponding to more than 5 yr at or below 70°C. These changes are acceptable for device applications. Single-element detectors have been made using PST and their properties have been assessed