Flux method
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Flux method is a method of crystal growth where the components of the desired substance are dissolved in a solvent (flux). The method is particularly suitable for crystals needing to be free from thermal strain and it takes place in a crucible made of non-reactive metal such as platinum, tantalum, niobium or other non-reactive elements. However, other common crucible materials include oxides such as Alumina, Zirconia, and Boron nitride. Crucibles are normally sealed in evacuated quartz ampoules or reactions take place in controlled atmosphere furnaces. A saturated solution is prepared by keeping the constituents of the desired crystal and the flux at a temperature slightly above the saturation temperature long enough to form a complete solution. Then the crucible is cooled in order to cause the desired crystal to precipitate. Nucleation happens in the cooler part of the crucible. One advantage of this method is that the crystals grown display natural facets so that they can be used for optical experiments without the need for further polishing. A disadvantage is that most flux method syntheses produce relatively small crystals. However, some materials such as the "115" Heavy Fermion Superconductors (CeXIn5, X=Co,Ir,Rh) may grow up to a few centimeters. The growth can happen by spontaneous nucleation or growth on a seed.
