Characterization of a Nanosized Iron Powder by Comparative Methods

Abstract

Fe nanopowder, derived from microwave plasma synthesis (Materials Modifications Inc., Fairfax, VA), was obtained and characterized for particle size and size distribution. The methods used included dynamic light scattering (DLS), static laser scattering (SLS), surface area and size by Brunauer, Emmett, and Teller (BET) analysis, small angle neutron scattering (SANS), neutron diffraction (ND), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Based on these methods, it was concluded that the Fe powder was composed of nanosized particles, but in micrometer-sized aggregates. DLS indicated a mean agglomerate size with a single mode distribution of 70 ± 6 nm. In contrast, SLS revealed a wide bimodal distribution ranging from 0.5 to 20 μm. The mean particle sizes that resulted from BET and XRD analyses were 60 nm and 20 nm, respectively. SANS, in combination with ND, determined that the powder had a bimodal distribution of mean size 24 and 64 nm. TEM and FESEM confirmed that the powder is composed of 50–80 nm particles that are found in large, dendritic particle agglomerates that are on the order of micrometers. The information derived from these results indicates that all of the selected methods were helpful in making an accurate and complete characterization of the powder.