Synthesis by Molecular Decomposition

In this technique, nanosize powders are formed by the decomposition (or atomic level fragmentation) of a larger molecule on removing unwanted or fugitive constituents. Initially, a large molecule is synthesized such that it contains the desired constituents as well as some fugitive constituents. This precursor material is subsequently contacted with a liquid in which the precursor is insoluble. However the liquid must be such that it does react with the precursor to form the desired insoluble product in a nanosize form and also form soluble species containing the fugitive constituents. The removal of the fugitive constituents from the precursor molecule leads to fragmentation at the atomic or molecular level, thereby paving the way to the formation of nanosize powders of the desired product.

There are several technologies currently available for producing nano-particles. They are based on mechanical milling, vapor condensation, laser ablation, plasma techniques, sol-gel processing, combustion synthesis, chemical precipitation and spray pyrolysis. Many of these techniques are very expensive while others produce hard agglomerates in the 30 to 50 nano-meters range because the process does not have enough control over particle growth. The University of Utah technology overcomes these drawbacks as shown in Table 1 below: