Synthesis of metal oxide nanocrystals

The synthesis of metal oxide nanocrystals by wet chemical processes can be divided basically into two major groups (a) chemical synthesis method based on the hydrolysis of metal alkoxides or metal halides (b) chemical synthesis based on the nonhydrolytic method. Examples of these methods are described below. 

The chemical synthesis of metal oxide nanocrystals based on hydrolysis falls into two major groups hydrolysis of metal alkoxides hydrolysis of metal halides, and other inorganic salts. Metal alkoxide compounds are defined as compounds that have metal-oxygen-carbon bonds. Si(OC2H5)4 (tetraethyl orthosUicate or TEOS), for instance, is an alkoxide compound. This class of compound is highly reactive with water. Because the hydroxyl ion (OH ) becomes bonded to the metal of the organic precursor, this reaction is called hydrolysis. Equation (50) shows a typical hydrolytic reaction of an alkoxide compound [100] ... 

Heat-up is a simple but effective method of synthesizing highly uniform nanocrystals, which yields a degree of size uniformity comparable to that of the best result from the hot injection method. This method is adopted mainly for the synthesis of metal oxide nanocrystals. In this section, we describe the synthetic procedure of iron oxide nanocrystals via the heat-up method as a representative example (23-25). 

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