Precursor Routes
Approach: Decrease diffusion distances through intimate mixing of cations .
Advantages: Lower reaction temps, possibly stabilize metastable phases, eliminate intermediate impurity phases, produce products with small crystallites/high surface area.
Disadvantages: Reagents are more difficult to work with, can be hard to control exact stoichiometry in certain cases, sometimes it is not possible to find compatible reagents (for example ions such as Ta5+ and Nb5+ immediately hydrolyze and precipitate in aqueous solution).
Methods: With the exception of using mixed cation reactants, all precursor routes involve the following steps: