The impact of carbon coating on the synthesis and properties of α"–Fe₁₆N₂ powders

Journal Article · Mon Apr 18 00:00:00 EDT 2016 · Physical Chemistry Chemical Physics. PCCP (Print)

DOI:https://doi.org/10.1039/C6CP00737F· OSTI ID:1252149

Bridges, Craig A. ^[1]; Brady, Michael P. ^[1]; Rios, Orlando ^[1]; Allard, Lawrence F. ^[1]; Meyer, III, Harry M. ^[1]; Huq, Ashfia ^[1]; Jiang, Yanfeng ^[2]; Wang, Jian -Ping ^[2]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Univ. of Minnesota, Minneapolis, MN (United States)

This study presents the preparation of carbon composite Fe₁₆N₂ powders, and the influence of a protective carbon coating on the yield and magnetic properties of Fe₁₆N₂. Nanoparticle precursors with and without carbon were reacted under ammonia gas flow to produce Fe₁₆N₂. X-ray diffraction indicates that the powders contain typically 50-60% Fe₁₆N₂, with the remaining phases being unreacted iron, Fe₄N or Fe₃N. Transmission electron microscopy demonstrates that the carbon coating is effective atnd reducing the level of sintering of Fe nanoparticles during the reduction stage prior to ammonolysis to form Fe nanoparticles. In situ TEM was used to observe loss of ordering in the nitrogen sublattice of carbon composite Fe₁₆N₂ powders in the range of 168 °C to 200 °C. Magnetic susceptibility measurements show maximum values for saturation magnetization in the range of 232 emu/g^-1, and for coercivity near 930 Oe, for samples measured up to 2T applied field at 300K.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1252149
• Journal Information: Physical Chemistry Chemical Physics. PCCP (Print), Vol. 18, Issue 18; ISSN 1463-9076
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
carbon coating
iron nitride
ammonolysis
magnetization
diffraction