Experimental
It is sometimes difficult to experimentally measure nucleation rate. The supercooling necessary to get a measurable rate may be at a temperature too low to allow for measurable growth rates. Gustav Tammann developed a method, known as the Tammann or “development” method. In this method, crystals are nucleated at a low temperature Tn and then grown at a higher temperature Tg. For validity of this method, the nucleation rate, I, has to be greater at the nucleation temperature Tn than at the growth temperature Tg; I(Tn)>> I(Tg), and the growth rate U must be greater at the growth temperature than at the nucleation temperature Tn ; U(Tg) >> U(Tn). Since the clusters are heated to a larger temperature with a larger critical radius requirement, clusters no longer meet the critical radius requirement and remelt. A method to heat the particles carefully must be used.
Koster proposed a method for nucleation of metallic glasses. This method considers the sizes of different crystals and attempts to determine when they were formed using data of their growth rates. It can be used for both homogeneous and heterogeneous nucleation.
Read more about this topic: Nucleation
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