Temperature dependence of the pyroelectric voltage response to step infrared signals in triglycine sulphate

An expression is derived for the pyroelectric (PE) voltage response to step radiation signals which can be applied up to temperatures close to the Curie point Tc under a ``small-signal'' condition. Based on the Curie-Weiss law and the thermodynamic theory of a second-order ferroelectric transition, a discussion is given of the temperature dependence of the parameters of the PE voltage response: initial slope, peak value, rise time, and fall time as functions of sample parameters and load resistance. It is found that the PE voltage may reach a maximum close to Tc, and expressions are derived for this value as well as for the temperature at which it occurs. These results were checked in detail on 12 samples of single-crystalline triglycine sulphate for temperatures from 20 °C to the Curie point, and good agreement between theory and experiment was observed. The application of the results to PE detection of ir is considered.