Low temperatures pyroelectric properties

In the past, the major interest has been in the room temperature operating pytoelectric materials and relatively few pyroelectric measurements have been made at low temperatures. The low temperature pyroelectrics could be more efficient IR detectors as (1) ferroelectrics with low curie temperatures tend to show near second order behavior with large pyroelectric coefficients over wide temperature range. (ii) At low temperatures the secondary pyroelectric contribution which is often large and opposite in sign to the primary effect at room temperature, decreases rapidly and there can be unexpectedly large pyroelectric coefficients. (iii) Specific heat and electrical losses decrease at low temperature. (iv) Signal to noise ratio increases as temperature decreases. All these factors generally raise the figure of merit of the pyroelectric devices. In this paper we report the low temperature measurements of the pyroelectric and dielectric properties of several ferroelectric and nonferroelectric materials and discuss the suitablity of the pyroelectric material for device operation in the ambient conditions in the outer space.