Title: Avrami equation
Long Title: IUPAC Gold Book - Avrami equation
DOI: 10.1351/goldbook.A00545
Status: current

Definition
An equation, describing crystallization kinetics, of the form: \[1 - \varphi _{c} = \rm{e}^{K\ t^{n}}\] where \(\varphi _{c}\) is the crystalline volume fraction developed at time \(t\) and constant temperature, \(K\) and \(n\) are suitable parameters. \(K\) is temperature dependent. According to the original theory, \(n\) should be an integer from 1 to 4, the value of which should depend only on the type of the statistical model; however, it has become customary to regard it as an adjustable parameter that may be non-integral.

Related Terms
- crystallization: https://goldbook.iupac.org//terms/view/C01434
- volume fraction: https://goldbook.iupac.org//terms/view/V06643

Source
- Purple Book, 1st ed., p. 85 (http://old.iupac.org/publications/books/author/metanomski.html)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/A00545/html
- json: https://goldbook.iupac.org/terms/view/A00545/json
- xml: https://goldbook.iupac.org/terms/view/A00545/xml

Citation: Citation: 'Avrami equation' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.A00545
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Accessed: 2026-08-06T08:05:03+00:00