An applied electric field can reversibly change the temperature of an electrocaloric material under adiabatic conditions, and the effect is strongest near phase transitions. We demonstrate a giant electrocaloric effect (0.48 kelvin per volt) in 350-nanometer PbZr(0.95)Ti(0.05)O3 films near the ferroelectric Curie temperature of 222 degrees C. A large electrocaloric effect may find application in electrical refrigeration.

The physics of pyroelectric detectors is reviewed, including a discussion of response and electronic noise and their dependence on device design and material parameters. Other sources of noise are described, particularly as generated by environmental effects such as microphony, together with techniques for their minimisation. The range of ferroelectric materials which have been assessed for use in pyroelectric detectors is reviewed and their properties compared, particularly from the aspect of application to different types of device. Finally, an account is given of the wide range of applications for which pyroelectric detectors have been used, including a detailed description of both the pyroelectric vidicon and pyroelectric arrays and their application to thermal imagers.

Rietveld refinements using neutron powder profiles are reported for a series of samples (commonly known as PZT), with x ranging from to . Cation shifts, octahedral distortion and tilts are determined with varying composition across the ferroelectric rhombohedral regions, and , of the PZT phase diagram. These parameters are then used in conjunction with a simple Landau-Devonshire model to investigate the nature of the phase transition. It is found that the cation shifts, octahedral distortion and tilt angles decrease with increasing Ti content, but, surprisingly, the octahedral strain, as indicated by the rhombohedral angle, increases. This is in contrast to the case for all other known rhombohedral perovskites. Furthermore, the refined anisotropic displacement parameters of the cations are anomalous and cannot be accounted for by the average crystal structure. A model is presented in which a domain-type `local' structure is considered, containing `ordered' additional cation displacements, consistently with the reports of extra reflections observed in electron microscopy studies by Viehland et al, Dai et al and Ricote et al.

No abstract