PYROELECTRIC CERAMICS AND DEVICES.

The PbZrO//3-PbTiO//3 ceramic system has been studied in the past for a variety of applications, including capacitor dielectrics and piezoelectrics. The inclusion of lead iron niobate (Pb//2FeNbO//6) permits the phase transition temperatures to be modified to allow pyroelectric device operation over a wide range. Use of uranium as a dopant reduces the dielectric constant and loss, increasing the pyroelectric figures-of-merit in the system so that values can be achieved which equal or exceed those of the best single crystal pyroelectrics. DC and low frequency AC conductivity measurements have been made as functions of temperature and uranium concentration. For uranium doping levels less than 0. 2 mole %, conductivity is dominated by hole hopping, with lead vacancies in the lattice acting as acceptor centres. Above this concentration, there is a change in the conduction type to electron hopping with the uranium ions acting as electron donors. Pyroelectric ceramics based upon this solid solution system have been applied to a variety of infra-red detector arrays.