Tem Studies on the Morphology, Size Distribution and Structure of Nanocrystalline Iron Particles Using a Formvar Embedded Preparation Technique

Abstract

ABSTRACTA new, simple and effective method was developed for preparing specimens of Fecarbide ultrafine particles (UFP), by suspending them in Formvar films. Various samples of Fe-carbide UFP's were obtained by a laser pyrolysis process by varying the process parameters. The UFP samples were mixed with different concentrations of Formvar in ethylene dichloride solution. The sample particles were embedded in ultra-thin Formvar films with thickness of 20 nm or more and mounted on the 200 mesh copper TEM grids. The influences of the concentration of the Formvar solution and the amount of sample powder on the UFP distribution in the micrographs were investigated to determine the optimal film-making parameters. The different sizes and same spherical morphology for the various UFP samples were revealed, indicating the main diameters to be between 5–20 nm. Compared with the size values obtained by using XRD, the UFP size measurements by the new process are in good agreement. The crystalline features and the surface of the UFP's are presented and confirmed by micro-diffraction studies.