Combustion aerosol synthesis of nanoscale ceramic powders

A high-temperature combustion aerosol process for the production of nanoscale ceramic oxide powders is described. This process uses a reactive organic aerosol spray to deliver dissolved ceramic precursor compounds to a high-temperature reaction zone. Upon entering the heated zone, the precursor compounds vaporize from the organic droplet surface, react with oxygen in the surrounding environment, and subsequently recondense as a very high surface area oxide fume. Each individual carrier droplet functions as an isolated micro reactor. By controlling the reaction conditions, the vaporization and nucleation steps that regulate nanoscale powder production can be adjusted to produce nanoscale particles. Through the use of a reactive spray-microreactors-the collisions that lead to extensive agglomeration and loss of surface area are minimized. Using this process, nanoscale magnesia, zirconia, and yttrium stabilized zirconia powders with 10-20 nm particle size were produced. Narrow particle size distributions and high chemical purity were obtained. For the yttria stabilized zirconia samples, sintering tests indicated sintering to 98% of theoretical density at 1373 K, several hundred kelvin lower than sintering temperatures reported for zirconia powders with larger particle sizes. (C) 1998 Elsevier Science Ltd. All rights reserved.