{"term":{"id":"03420","title":"λ-transition","longtitle":"IUPAC Gold Book - λ-transition","doi":"10.1351\/goldbook.T03420","code":"T03420","status":"current","synonym":"<em>synonym<\/em>: lambda-transition","definitions":[{"id":1,"text":"A second-order or higher-order transition, in which the heat capacity shows either a discontinuity (second-order) or a vertex (higher-order) at the transition temperature. Example: The transition at \\(846\\ \\rm{K}\\), accompanied by a finite change in specific heat capacity at constant pressure \\(C_{p}\\), of the low-temperature polymorph of quartz to the high-temperature polymorph.","links":[{"term":"heat capacity","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/H02753"},{"term":"higher-order transition","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/H02822"},{"term":"second-order","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S05531"},{"term":"specific heat capacity","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/S05800"}],"sources":["PAC, 1994, 66, 577. 'Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)' on page 584 (https:\/\/doi.org\/10.1351\/pac199466030577)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/T03420\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/T03420\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/T03420\/plain"},"citation":"Citation: 'λ-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.T03420","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":"2026-06-20T08:10:41+00:00"}}