Disruptive Inventions in Electroceramics

Abstract

Disruptive inventions in electroceramics arose out of need for greatly improved properties or short-supply of existing materials, or, more importantly, serenpedity. In the case of ceramic capacitors, the key property of the material, dielectric constant, jumped from less than 10 (mica) to 100 (titania) to over 1000 (barium titanate ceramics) to over 10,000 (relaxor ferroelectrics) to over 100,000 (multilayer ceramics). The challenge for miniaturization demanded by integrated circuits was thus met. An excellent insulator such as barium titanate was converted into a good conductor by doping but the unexpected discovery was the abrupt increase in electrical resistivity over a million fold at the Curie temperature, opening new vistas of applications. The disruptive invention of superconductivity in oxide ceramics, that too at easily accessible, above liquid nitrogen, temperatures created unprecedented scientific efforts. The discovery of piezoelectric properties in lead zirconate titanate ceramics totally transformed the entire field of transducers, sensors and actuators. Mixing a piezoelectric ceramic powder and a polymer into a composite with controlled connectivity in 0, 1, 2 or 3 directions led to an unbelievable range of piezoelectric and electrostrictive properties and applications. Ceramics, noted for their opacity, have become endowed with superior electro-optic properties by magical alchemy.