Title: paracrystalline distortion factor
Long Title: IUPAC Gold Book - paracrystalline distortion factor
DOI: 10.1351/goldbook.14232
Status: current

Definition
Ratio of the statistical fluctuation \(\Delta a_{ik}\) of a lattice vector \(a_{i}\) along the direction \(a_{k}\) \[g_{ik} = \frac{\Delta a_{ik}}{a_{k}}\]

Notes
1) Values of \(g\) range from \(\pu{0}\) (distortion-free crystal) to \(\pu{0.03}\) (typical bulk polymer), to \(\pu{0.12}\) (\(\ce{SiO2}\) glass) to \(\pu{1}\) (Boltzmann gas).
2) \(g\) can be determined from measurements of the integral breadth of successive orders of Bragg reflections [18b].

Source
- PAC, 2011, 83, 1831. 'Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)' on page 1848 (https://doi.org/10.1351/PAC-REC-10-11-13)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/14232/html
- json: https://goldbook.iupac.org/terms/view/14232/json
- xml: https://goldbook.iupac.org/terms/view/14232/xml

Citation: Citation: 'paracrystalline distortion factor' 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.14232
License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.
Collection: If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .
Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.
Accessed: 2026-07-31T16:31:42+00:00