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Phase Transformation of Iron Oxide Nanoparticles by Varying the Molar Ratio of Fe 2+ :Fe 3+
Author(s) -
Alibeigi S.,
Vaezi M. R.
Publication year - 2008
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200800093
Subject(s) - maghemite , magnetite , crystallinity , ferrous , nanoparticle , coprecipitation , mössbauer spectroscopy , materials science , phase (matter) , precipitation , nuclear chemistry , iron oxide , ferric , inorganic chemistry , chemical engineering , analytical chemistry (journal) , chemistry , metallurgy , nanotechnology , crystallography , chromatography , physics , organic chemistry , meteorology , engineering , composite material
Co‐precipitation from a solution of ferrous/ferric mixed salt with the ratio of Fe 2+ :Fe 3+ = 1:2 in air atmosphere is not a reliable method to synthesize magnetite (Fe 3 O 4 ) nanoparticles because of the fact that Fe 2+ oxidizes to Fe 3+ and the molar ratio of Fe 2+ :Fe 3+ changes. Therefore, the phase composition changes from magnetite to maghemite (γ‐Fe 2 O 3 ). The influence of the initial molar ratio of Fe 2+ :Fe 3+ on the phase composition of nanoparticles, their crystallinity and magnetic properties was studied. Experimental data from XRD, FTIR, SEM, and VSM reveal that the appropriate method to synthesize magnetite nanoparticles is reverse precipitation from only ferrous salt. It is found that by decreasing the synthesis temperature and by increasing the concentration of alkaline solution and the ratio of Fe 2+ :Fe 3+ the crystallinity and the specific saturation magnetization (σ s ) are increased.