*3.1.2 Methodology*

FEI strata DB235 Dual Beam Workstation was used to analyze the sample which used Gallium ion source (Ion Beam) for milling and electron beam (SEM) for scanning purposes, with the adjusted angle between IB and EB of 520 . The area of interest of the sample was selected using SEM and was coated with the protective layer of Pt with the incorporation of FIB-induced decomposition of precursor gas. This protective layer helps in getting better cuts during milling [52]. The trench (by milling process) was dug into the sample in such a way that the there is no shadow of sample edges over the trench during the scanning of the sample. **Figure 2** shows the image of a cell (Adopted from Wierzbicki et al. [47]) with the shadow of trench onto cell and its corrected version [47]. Sub image A shows the shadow of trench onto cell in XY-axis whereas sub image B shows its corrected version. It is better to mill at the edge area, but it is only possible for samples with evenly balanced composition and structure; for other samples, it is suggested to impute the area of interest from the sample and bring it to the edge with the help of micromanipulator. Whereas, two additional trenches may be dug around the area of interest to avoid the deposition of sputtered sample [52, 53]. The milling is done using current beam of order 20 nA. The milling criteria depend upon the milling of number of cross-sections needed to get a clear 3D surface of the smallest possible particle [12].

The area should essentially be polished with the implication of low currents in pA range to polish the surfaces before analyzing the sample and once polished, the samples analyzed using SEM at various ranges of resolution to get the best morphological structures needed. For instance the sample of AlSi12 was analyzed using increments of 300 nm and for AlSi7Sr, increments of SEM used were 83 nm [29].
