Stela Zamfirescu

Evaluation of Mean Diameter values using Scherrer Equation Applied to Electron Diffraction Images

The aim of this work is to determine mean diameter of poly- crystalline samples using the Scherrer equation. These calculations represent a direct connection between the mean diameter, crystal structure and morphology by applying the Bragg angle and shape factor. Two samples are investigated, first a nano-sized particles of MgO and second a CVD (chemical vacuum deposition) obtained polycrystalline aluminum film. First, the shape factor and mean diameter are evaluated using direct measurement of particle morphology from BF-TEM (bright field - transmission electron microscopy) images. The value of mean diameter is determined by assuming a lognormal distribution. Second, the mean diameter values are evaluated using the Scherrer equation applied to SAED (selected area electron diffraction) images. We obtained for MgO nano-sized a mean diameter about 48 nm from the direct measurement, and 70 nm respectively using the Scherrer equation, and for Al film 77 nm and 70 nm, respectively.