ABSTRACT
Powders composed of particles of size smaller than 50-100 nm, often referred to as nanopowders or nanoparticles, have been the subject of growing research and development in the last 20 years and are now making inroads into the industrial production of ceramics. One reason for the growing interest in nanopowders is the interesting and improved properties observed for nanoparticles and solids with nanosize grains. Methods for synthesizing ceramic nanopowders are divided into four broad categories based on the state of the starting and final materials and, if present, intermediate materials: solid-solid, solid-vapor-solid, liquid-solid and liquid-vapor-solid. Some methods also limited in their capacity to produce commercial quantities of nanopowders. In general, the overall fabrication cost of the article and the benefits derived from improved properties due to a finer grain size in the fabricated article will often determine the use of nanopowders over micron or submicron powders.
