Annealing study of Fe 2O 3 nanoparticles: Magnetic size effects and phase transformations

X. N. Xu, Y. Wolfus, A. Shaulov, Y. Yeshurun, I. Felner, I. Nowik, Yu Koltypin, A. Gedanken

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


Sonochemically synthesized Fe 2O 3 nanoparticles were annealed in air or in vacuum while their magnetization was continuously recorded. Annealing in vacuum at temperatures T a between 240 and 450°C produced nanophases of γ-Fe 2O 3 with average particle size ranging from 4 to 14 nm, depending on T a. Phase transformation into α-Fe 2O 3 occurred directly by annealing in air, or via an intermediate Fe 3O 4 phase by annealing in vacuum at temperatures higher than 450°C. Mapping the correlation between the magnetic properties and the annealing conditions, enables control of the annealing process to obtain nanocrystals of γ-Fe 2O 3, α-Fe 2O 3, or Fe 3O 4 with different particle size and magnetic properties.

Original languageEnglish
Pages (from-to)4611-4616
Number of pages6
JournalJournal of Applied Physics
Issue number7
StatePublished - 1 Apr 2002


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