Amorphous versus Crystalline Oxide Materials

Compared to the hydrolysis of metal alkoxides, the method has the ability for producing a wider range of chemical compositions, including oxides or hydrous oxides, sulfates, carbonates, phosphates, and sulfides. However, the number of experimental parameters that must be controlled to produce uniform particles is generally higher. They include the concenttation of the metal salts, the chemical composition of the salts used as starting materials, the temperature, the pH of the solution, and the presence of anions and cations that form intermediate complexes. While a variety of particle sizes and shapes can be produced (Fig. 2.23), the morphology of the final particles can rarely be predicted (59,60). Furthermore, while amorphous as well as crystalline particles can be produced, the factors that determine the crystalline versus amorphous structure of the product are not clear (61). 

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