THIN-FILM ELECTROCERAMICS

Electroceramics in thin film form have a wide range of potential applications encompassing: capacitors, sensors, actuators, optical switches, superconductors and high temperature semiconductors. Here we briefly survey two of these areas; ferroelectrics and gas sensors. There is now increasing interest in thin films of ferroelectric ceramics for application as non-volatile memory capacitors, thermal imagers, piezoelectric sensors and electro-optic switches. Typical ferroelectric ceramics being considered are mixed oxides of lead, lanthanum, zirconium and titanium (PLZT). The characteristics of ferroelectric ceramics and the preparation of thin films by sputter deposition and by the sol-gel process are described. High surface area, porous, thin films of semiconducting ceramic oxides have application as gas sensors. The operation of such sensors based on tin oxide for detection of reducing gases in air is described and an example given of a thin film sensor produced by the sol-gel process. The use of a solid electrolyte electrochemical cell is described to investigate the reactions taking place on the catalytic surface of tin oxide.