02640 IUPAC Gold Book - glass transition 10.1351/goldbook.G02640 G02640 current 1 A second-order transition in which a supercooled melt yields, on cooling, a glassy structure. Below the glass-transition temperature the physical properties vary in a manner similar to those of the crystalline phase. Example: Lithium disilicate crystals melt at \(1305\ \rm{K}\); the melt can be supercooled to the glass-transition temperature at approximately \(773\ \rm{K}\) below which the viscous liquid freezes to a rigid amorphous glass. glass-transition temperature https://goldbook.iupac.org//terms/view/G02641 second-order transition https://goldbook.iupac.org//terms/view/S05531 PAC, 1994, 66, 577. 'Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)' on page 583 (https://doi.org/10.1351/pac199466030577) https://goldbook.iupac.org/terms/view/G02640/html https://goldbook.iupac.org/terms/view/G02640/json https://goldbook.iupac.org/terms/view/G02640/plain Citation: 'glass transition' 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.G02640 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-07-14T18:48:59+00:00