Hydrothermal synthesis and thermoelectric properties of nanostructured Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds

Research highlights: {yields} Single-phase Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} powders have been synthesized by a hydrothermal route. {yields} Hexagonal Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} naosheets due to the anisotropic growth of the crystals. {yields} The temperature gradients lead to directional arrangement nanosheet-agglomerates. {yields} Nanosheet-agglomerates are beneficial for improving the TE property of products. {yields} A maximum figure of merit of 0.86 is achieved at about 100 {sup o}C. -- Abstract: Single-phase Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds have been prepared by hydrothermal synthesis at 150 {sup o}C for 24 h using SbCl{sub 3}, BiCl{sub 3} and tellurium powder as precursors. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) have been applied to analyze the phase distributions, microstructures and grain sizes of the as-grown Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} products. It is found that the hydrothermally synthesized Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} nanopowders have a morphology dominated by irregular hexagonal sheets due to the anisotropic growth of the crystals. The Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} nanosheets are parallelly stacked in certain direction to form sheet-agglomerates attribute to the temperature gradients in the solution.