Bottom-up wet chemical synthesis and characterization of Bi$_{\mathrm{x}}$Te$_{\mathrm{y}}$ nanoparticles

Bi$_{\mathrm{x}}$Te$_{\mathrm{y}}$ is an interesting series of compounds for which certain x:y ratios result in formation of a natural superlattice structure. The different stoichiometric ratios, designated by the x and y, is better represented by (Bi$_{\mathrm{2}})_{\mathrm{m}}$(Bi$_{\mathrm{2}}$Te$_{\mathrm{3}})_{\mathrm{n}}$ where m and n are integers, and is an infinitely adaptable series. For this study, we have chosen x:y to be 1:1, 2:3 and 2:1 which are expected to form the natural superlattice with m and n values. The alternating layers of Bi$_{\mathrm{2}}$ groups and Bi$_{\mathrm{2}}$Te$_{\mathrm{3}}$ groups stack along the c-axis of the lattice according to the m:n ratio. Bi$_{\mathrm{2}}$Te$_{\mathrm{3}}$ is a well-studied thermoelectric material, and the work done in this project may have potential implications for optimizing the material. Using a bottom up wet chemical synthesis, the desired ratios have been produced in high yields. X-Ray Diffraction is consistent with the intended compounds, but also shows free tellurium as an impurity. Using Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy, the particles are found to be nanoscale and the elemental analysis shows the stoichiometry is close to the desired ratios.