Vacancy ordering in gamma-Fe2O3 nanocrystals observed by 57Fe NMR

Timothy J Bastow, Adrian Trinchi, Matthew Roland Hill, R Harris, Tim Muster

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Abstract

The identification by 57Fe internal field nuclear magnetic resonance (NMR) of hyperfine fields at four Fe sites in the (average) tetragonal unit cell of vacancy-ordered gamma-Fe2O3 (maghemite) is reported. The effects of vacancy redistribution due to annealing the partially vacancy-ordered form has been observed in the Fe-57 lineshape. In addition, the reduction of the particle size of the vacancy-ordered form has been observed to gradually eliminate the vacancy ordering and then to cause a transition from ferrimagnetism to superparamagnetism.
Original languageEnglish
Pages (from-to)2677 - 2681
Number of pages5
JournalJournal of the American Chemical Society
Volume321
Issue number17
DOIs
Publication statusPublished - 2009
Externally publishedYes

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