{"term":{"id":"00184","title":"aggregate","longtitle":"IUPAC Gold Book - aggregate","doi":"10.1351\/goldbook.A00184","code":"A00184","status":"current","also defines":"<em>also defines<\/em>: agglomerate, primary particle","definitions":[{"id":1,"text":"Certain materials used as catalysts or supports consist of spheroids smaller than \\(10\\ \\rm{nm}\\) in diameter, cemented into larger entities. A primary particle should be defined as the smallest discrete identifiable entity and the method of identification should be mentioned (e.g. transmission electron microscopy, scanning electron microscopy). An assemblage of such primary particles exhibiting an identifiable collective behaviour (e.g. chemical nature of the aggregated primary particles, texture of the aggregate, resistance to mechanical separation upon grinding) constitutes an aggregate. When describing the aggregates the criterion of identification should be mentioned. Strongly bonded aggregates are called agglomerates.","contexts":[],"links":[{"term":"electron microscopy","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/E02002"},{"term":"resistance","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/R05315"},{"term":"transmission","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/T06477"}],"sources":["PAC, 1991, 63, 1227. 'Manual on catalyst characterization (Recommendations 1991)' on page 1231 (https:\/\/doi.org\/10.1351\/pac199163091227)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/A00184\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/A00184\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/A00184\/plain"},"citation":"Citation: 'aggregate' 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.A00184","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":"2026-06-07T08:09:43+00:00"}}