Infra red detectors with improved sensitivity - using phase change in mixed crystal of lead and barium zirconates

摘要

Pyroelectric detector with a pyroelectric crystal operating in a region where the spontaneous polarisation depends not only on the temp. but also on a phase-transition between a ferroelectric- and an antiferroelectric- phase of different crystal structures, the result being improved sensitivity in i.r. detectors for temp. measurement or in image prodn. using several detectors in a matrix or a vidicon. A mixed crystal is used, either lead zirconate and barium zirconate (I) or sodium niobiate and lead zirconate. By altering the compsn. of the mixed crystal, applying a polarising field, and using heat, if necessary, devices can be applied over a wide temp. range and in many applications.