Fabrication of nanocrystalline Mg 2Si via ball milling process: Structural studies

Abstract

In this work, nanocrystalline Mg 2Si material was fabricated via wet ball milling process using n-hexane as process control agent. Milling parameters, with emphasis on milling time and ball size, and conditions were studied in order to understand the process and investigate its effect on the structural features of the material. Crystallite size evolution during ball milling was followed by powder X-ray diffraction measurements as well as Transmission Electron Microscopy studies. Scanning Electron Microscopy images showed the agglomeration of the crystallites and the formation of particles with minimum mean size of 1.6μm. The simultaneous formation of MgO in the material is shown through powder X-ray diffraction and electron diffraction TEM studies. The broadened PXRD peaks were analyzed and crystalline size was estimated based on Scherrer equation. The crystallite size distributions were studied based on the analysis of Dark Field images and were well described based on a Log-Normal equation. The effect of the size of the balls during milling was clear and leads to bi-modal and uni-modal distributions when large and small balls were used, respectively. IR reflectivity spectra showed blueshifting and broadening of the modes on increasing milling time that may also be assigned to decreasing grain size and particle shape effects. © 2011 Elsevier B.V.