User:Groggler/Flux method

The flux method is a crystal growth method where starting materials are dissolved in a solvent (flux), which is typically a solid at room temperature and heated to a liquid, and are precipitated out as crystals of a desired compound. Typical compounds used as the flux are inorganic compounds capable of melting at low temperatures and cause a large change in solubility with temperature. The flux is molten in a highly stable crucible that does not react with the flux. Metal crucibles such as platinum, tantalum, and niobium are used for the growth of oxide crystals. Ceramic crucibles such as alumina, zirconia, and boron nitride are used for the growth of metallic crystals. For air-sensitive growths, contents are sealed in ampoules or placed in atmosphere controlled furnaces.

The starting materials, flux and crucible are heated to form a complete solution, then cooled to a temperature where the solution is fully saturated. Cooling the solution further causes crystals to precipitate, and decreases the concentration of starting materials in solution. Removal of solvent is another method of achieving supersaturation. This process is repeated, precipitating more crystal out, and making the solution more rich in flux. The process is stopped by removing the growth from the furnace, or by allowing the furnace to reach room temperature.

Self-Flux
Using a flux that is part of the desired compound, a "self-flux" can reduce contamination of the crystal by the flux. For metal crystals, some examples of self-fluxes would be: tin in the growth of PtSn4, antimony in the growth of CrSb2, and lead in the growth of SOMETHING.