## 3 Results and Discussion
### Transport Property Evaluation  
Nanostructured TE materials were consolidated using SPS, the critical consolidation parameters (sintering temperature, holding time, pressure, and heating rates), and characteristics of the resultant pellets are presented in detail in Table 2. All pellets possess a compaction density of about 78-83% of the theoretical density of the material, with about 20% porosity. The transport data in the temperature range 300-523 K are presented in Figure 3a-e. Table 2 also summarizes the transport data at room temperature and at the temperature where maximum \(\mathbf{ZT}\) was obtained for the given material composition. No adverse effects in the transport properties were observed due to the presence of surface oxides. The Seebeck coefficient (**S**) is the key parameter to demonstrate that the materials have the transport characteristics (n- vs. p-type) planned for from the stoichiometry of the precursors. Figure 3a reveals the sign and magnitude of measured \(S\) values, which clearly indicates n-type character for Bi\({}_{2}\)Te\({}_{3}\) and Bi\({}_{1.8}\)Sb\({}_{0.2}\)Te\({}_{3}\), while p-type character was observed for Bi\({}_{0.5}\)Sb\({}_{1.5}\)Te\({}_{3}\) and Sb\({}_{2}\)Te\({}_{3}\). This, in agreement with literature, is a strong indication that the MW-assisted chemical synthesis process is capable of producing the phases that are designated by the initial ratio of precursor materials, without needing additional stabilizers, reflux, or other chemicals to avoid phase separation during synthesis. An interesting comparison for the obtained \(S\) could be for Bi\({}_{0.5}\)Sb\({}_{1.5}\)Te\({}_{3}\) composition with arc-melted and textured (via solidification under magnetic field) material [11], where our \(S\) value is about two times \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Samples** & **BE [eV]**[30] & **Fraction** & **Assigned to [31]** & _iep_ (pH) \\ \hline \multirow{4}{*}{Bi\({}_{2}\)Te\({}_{3}\)} & 157 & 13.11 & Bi & \multirow{4}{*}{6.3} \\  & 159 & 9.83 & Bi–O (Bi\({}_{2}\)O\({}_{3}\)) & \\  & 573 & 8.77 & Te & \\  & 577 & 19.68 & Te–O (TeO\({}_{2}\)) & \\ \hline \multirow{4}{*}{Bi\({}_{1.8}\) Sb\({}_{0.2}\)Te\({}_{3}\)} & 157 & 6.06 & Bi & \multirow{4}{*}{6} \\  & 528.3 & 2.08 & Sb & \\  & 573 & 6.5 & Te & \\  & 159 & 4.56 & Bi–O (Bi\({}_{2}\)O\({}_{3}\)) & \\  & 530 & 1.42 & Sb–O (Sb\({}_{2}\)O\({}_{3}\)) & \\  & 577 & 10.35 & Te–O (TeO\({}_{2}\)) & \\ \hline \multirow{4}{*}{Bi\({}_{0.5}\) Sb\({}_{1.5}\)Te\({}_{3}\)} & 157 & 2.38 & Bi & \multirow{4}{*}{4.5} \\  & 528.3 & 12.64 & Sb & \\  & 573 & 11.46 & Te & \\  & 159 & 2.38 & Bi–O (Bi\({}_{2}\)O\({}_{3}\)) & \\  & 530 & 8.43 & Sb–O (Sb\({}_{2}\)O\({}_{3}\)) & \\  & 577 & 15.7 & Te–O (TeO\({}_{2}\)) & \\ \hline \multirow{4}{*}{Sb\({}_{2}\)Te\({}_{3}\)} & 528.3 & 14.92 & Sb & \multirow{4}{*}{3.3} \\  & 573 & 8.38 & Te & \\ \cline{1-1}  & 530 & 9.94 & Sb–O (Sb\({}_{2}\)O\({}_{3}\)) & \\ \cline{1-1}  & 577 & 22.13 & Te–O (TeO\({}_{2}\)) & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: XPS peak fitting results for Bi 4f, Sb 3d, and Te 3d regions for bulk samples, and the measured _iep_ values for the Bi\({}_{2-x}\)Sb\({}_{x}\)Te\({}_{3}\) samples. lower. Electronic transport properties are strongly correlated in classical materials, as well as by charge carrier density, defects, and scattering events. Therefore, it is possible to observe different transport values in the same composition due to the microstructure, which in turn is mostly determined by the synthesis and processing methods. The textured material possessed larger micro- to nano-sized grains, or layers, causing strong scattering of charge carriers and heat carrier phonons (decrease electronic and thermal conductivity), which in turn enhanced the S. SEM and TEM micrographs of our samples prepared with solution chemical process showed small nano-sized, nearly identical crystalline nanoplatelets.