Unidirectional charge flow was observed in potassium tantalum niobate, ${\mathrm{KTa}}_{0.6}$${\mathrm{Nb}}_{0.4}$${\mathrm{O}}_3$, films. These films of relaxor-type diffuse phase transition material were formed by metalorganic deposition and had a polarization gradient normal to the surface of the films. Novel charge pumping was observed in the active operation of simple two-terminal structures by excitation with periodic, strong electric fields. Such operation also showed a large pseudopyroelectric response. Effective pyroelectric coefficients as large as 2×${10}^{\mathrm{-}5}$ C/${\mathrm{cm}}^2$ °C have been obtained.

• Received 10 June 1991

DOI:https://doi.org/10.1103/PhysRevLett.68.1778