Size-dependent magnetic properties of γ-Fe2O3 nanocrystallites. (11th October 2019)

• Record Type: Journal Article
• Authors: Kamali, S; Chen, C J; Bates, B; Johnson, C E; Chiang, R K
• Is Part Of: Journal of physics. Volume 32:Number 1(2020)
• Publication Date: 2019-10-11
• Subjects: nanocrystallites -- magnetization measurements -- Mössbauer spectroscopy -- maghemite; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ab41be
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: A route for synthesizing monodisperse magnetic nanocrystallites of maghemite, -Fe2 O3, with various sizes has been revisited. A systematic investigation of three -Fe2 O3 nanocrystalline samples by different techniques has been performed to characterize their size-dependent magnetic properties. Zero-field-cooled and field-cooled magnetization measurements reveal that the superparamagnetic blocking temperatures are around 230 K, 170 K, and 50 K for the 15.0 nm, 11.8 nm, and 6.1 nm nanocrystallites, respectively. Low-temperature Mössbauer spectra show that all three nanocrystallites have the maghemite structure with all the vacancies in the B-sites. Furthermore, detailed analysis shows that there are more vacancies on the B-sites for the 6.1 nm nanocrystallites compared to 0.33 for the bulk maghemite.