Hydrothermal synthesis and thermoelectric properties of nanostructured Bi0.5Sb1.5Te3 compounds

Single-phase Bi0.5Sb1.5Te3 compounds have been prepared by hydrothermal synthesis at 150 °C for 24 h using SbCl3, BiCl3 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 Bi0.5Sb1.5Te3 products. It is found that the hydrothermally synthesized Bi0.5Sb1.5Te3 nanopowders have a morphology dominated by irregular hexagonal sheets due to the anisotropic growth of the crystals. The Bi0.5Sb1.5Te3 nanosheets are parallelly stacked in certain direction to form sheet-agglomerates attribute to the temperature gradients in the solution.

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► Single-phase Bi0.5Sb1.5Te3 powders have been synthesized by a hydrothermal route.
► Hexagonal Bi0.5Sb1.5Te3 naosheets due to the anisotropic growth of the crystals.
► The temperature gradients lead to directional arrangement nanosheet-agglomerates.
► Nanosheet-agglomerates are beneficial for improving the TE property of products.
► A maximum figure of merit of 0.86 is achieved at about 100 °C.