## 3 Results and Discussion  
Figure 1a shows the XRD peaks of the as-casted samples. When fifty-fifty atomic percent of aluminum and antimony were maintained, the melting shows an excess of antimony in the XRD image. Since the melting was done in a controlled condition, no sublimation of antimony was observed. Yet, some amount of remnant oxygen, in considerably small quantities, might have oxidized aluminum, leading to the deficit of aluminum. Most XRDs have a detection limit of up to 5% by weight [15], which is why trace amounts of alumina could have remained undetected. Another explanation could be that the difference of stoichiometry may be caused by the difference of purity of the two elemental shots used. The extra high purity of Sb could have resulted in a deficit of aluminum, which needed to be compensated. In order to compensate for this loss, two at % excess of aluminum were added and the melting was run again. XRD peaks with two at % excess of Al as-casted samples showed a single-phase bulk AlSb. Despite that, the intermetallic semiconductor was extremely brittle, and no thermoelectric properties could be measured. Consequently, the samples were pulverized using mortar and pestle and consolidated by VHP. After VHP, two at % excess Al sample showed remnant peaks of excessive Sb in the matrix. Figure 1b shows the XRD data for vacuum hot-pressed samples. The discrepancy might be due to the formerly mentioned limitation of X-ray diffraction techniques. To further compensate, three at % of aluminum was added, and the process was repeated. Thereby, both the as-casted and VHPed samples showed single-phase bulk AlSb. In order to highlight minor peaks in this AlSb system further, the y-axis in the XRD data was modified to a logarithmic scale. Figure 1c,d are the respective logarithmic scale data for as casted and VHPed samples. After the log has been added, a small peak of remnant Sb can be seen in Figure 1d, which was absent in Figure 1b. The relative densities of the VHPed samples in both the cases were \(\sim\)94%, as shown in Table 1. SEM images in Figure 2 show the existence of voids in the morphology. In order to further increase the density and reduce such voids, the casted sample was pulverized by HEVM. X-ray diffraction data show broadening of the peaks, which could be due to a decrease in particle size [3]. The milled powders were then consolidated by vacuum hot pressing, and relative density of \(\sim\)99% was achieved. SEM images confirm that after vibratory milling, the shapes of the particles changed to near round shapes as opposed to the irregular shapes found by manual pulverizing. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Description** & **Relative Density (\%)** \\ \hline S1\({}_{2}\) * & Pulverized by MP and then & 94 \\  & VHP & \\ \hline S2\({}_{3}\) * & Pulverized by MP and then & 94 \\  & VHP & \\ \hline S3\({}_{3}\) * & Pulverized by HEVM and then & 99 \\  & VHP & \\ \hline \hline \end{tabular}
* \(\mathrm{SI_{x}}\): x denotes x at. % excess of Al used.  
\end{table} 
Table 1: Relative densities of the VHPed samples under different pulverization techniques. Figure 1: XRD data for (**a**) as casted and pulverized samples, (**b**) for VHPed samples, (**c**) as-casted samples in the logarithmic scale and (**d**) VHPed samples in the logarithmic scale. Figure 2: SEM images of controlled melting sample pulverized by (**a**) mortar-pestle and (**c**) HEVM and subsequently VHPed (**b**,**d**). Due to the relatively large band gap, the electrical resistivity of the single-phase bulk AlSb material is very high. Consequently, the thermoelectric properties of such material could not be calculated by the ZEM-3 machine. This could be because a large amount of energy is needed for the electrons at the valence band to be promoted to the conduction band. However, the semiconductor showed enough electrical conductivity for thermoelectric measurements when small amounts of remnant antimony would remain within the matrix.