Crystalline Magnetic Gels and Aerogels Combining Large Surface Areas and Magnetic Moments

The production of materials that simultaneously combine large surface areas and high crystallinities is a major challenge. Conventional sol-gel chemistry strategies to produce high-surface-area gels and aerogels generally result in amorphous or poorly crystalline materials. To attain proper crystall...

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Veröffentlicht in:Langmuir : the ACS journal of surfaces and colloids. - 1992. - 39(2023), 10 vom: 14. März, Seite 3692-3698
1. Verfasser: Berestok, Taisiia (VerfasserIn)
Weitere Verfasser: Chacón-Borrero, Jesús, Li, Junshan, Guardia, Pablo, Cabot, Andreu
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2023
Zugriff auf das übergeordnete Werk:Langmuir : the ACS journal of surfaces and colloids
Schlagworte:Journal Article
Beschreibung
Zusammenfassung:The production of materials that simultaneously combine large surface areas and high crystallinities is a major challenge. Conventional sol-gel chemistry strategies to produce high-surface-area gels and aerogels generally result in amorphous or poorly crystalline materials. To attain proper crystallinities, materials are exposed to relatively high annealing temperatures that result in significant surface losses. This is a particularly limiting issue in the production of high-surface-area magnetic aerogels owing to the strong relationship between crystallinity and magnetic moment. To overcome this limitation, we demonstrate here the gelation of preformed magnetic crystalline nanodomains to produce magnetic aerogels with high surface area, crystallinity, and magnetic moment. To exemplify this strategy, we use colloidal maghemite nanocrystals as gel building blocks and an epoxide group as the gelation agent. After drying from supercritical CO2, aerogels show surface areas close to 200 m2 g-1 and a well-defined maghemite crystal structure that provides saturation magnetizations close to 60 emu g-1. For comparison, the gelation of hydrated iron chloride with propylene oxide provides amorphous iron oxide gels with slightly larger surface areas, 225 m2 g-1, but very low magnetization, below 2 emu g-1. Thermal treatment at 400 °C is necessary to crystallize the material, which results in a surface area loss down to 87 m2 g-1, well below the values obtained from the nanocrystal building blocks
Beschreibung:Date Completed 14.03.2023
Date Revised 14.03.2023
published: Print-Electronic
Citation Status PubMed-not-MEDLINE
ISSN:1520-5827
DOI:10.1021/acs.langmuir.2c03372