There is currently a great interest in size effects in materials. There are many properties that change dramatically when the grain size or component dimensions are below 100 nm. A wide range of nanoscale ceramic powders have been synthesised with dimensions in the nanometre range. However, during conventional sintering the grain size can increase rapidly in the final stages of densification, leading to micrometer scale grains. The rapid heating/cooling afforded by Spark Plasma Sintering (SPS) allows densification to be achieved with minimal grain growth. We are researching the effect of grain size on the mechanical properties of structural nanoceramics and the properties of ferroelectric and varistor nanoceramics. Ferroelectrics are used for non-volatile memories, and actuators and sensors in Microelectromechanical Systems (MEMS). The increasing demand for size reduction in the microelectronics industry is approaching the nanometre scale, where experimental and theoretical work is showing that the properties of materials diverge. We have recently demonstrated for the first time that Aurivillius phase ferroelectric ceramics with grain size <100 nm maintain their ferroelectric properties, albeit reduced.

The work and its context are also described in Nanotechnology News:
http://nanotechweb.org/cws/article/tech/40715