USING FERROELECTRIC MATERIALS FOR MICROWAVE ELECTRONICS.

Thin-film ferroelectric materials have received considerable attention because of their growing use in electronic, electro-optic, optical and acoustic devices. Potential applications include random access memories, pyroelectric detectors, acoustic transducers and microwave devices.

An important characteristic of these materials is the ability to change their dielectric constants by an externally applied electric field. This idea is being pursued in a class of novel high-temperature-superconducting tunable microwave devices such as microstrip line phase shifters, high-Q resonators and tunable filters. Of the various ferroelectric materials, perovskite oxide thin films are considered potential candidates for tunable microwave devices because of their high dielectric constant.

As part of its program on new non-linear dielectric films, scientists from NIST and the University of Colorado at Boulder have investigated perovskite oxide thin films for cryogenic and ambient temperature applications. In a recent technical paper, they discuss film growth as well as the structural and low- frequency dielectric properties of the films. They also present dielectric data obtained on some bulk samples and, in order to understand the effect of strain on dielectric properties, present results on high-resolution x-ray diffraction studies on some of the films.