Abstract
Nanocrystalline bismuth telluride, Bi2Te3 has been synthesized by mechanical alloying (MA) the powder mixture composed of Bi and Te in the inert gas atmosphere within a short duration of 15 min. Microstructure characterization of the prepared powder has been investigated adopting the Rietveld’s method using X-Ray diffraction (XRD) data and analyzing high-resolution transmission electron microscopy (HRTEM) images. The XRD pattern of 15 min milled powder is composed of reflections of major Bi2Te3 phase with other two minor phases. Detailed structural information of these minor phases has been reported here which was not explored in any previous works. XRD analysis reveals that the stoichiometric Bi2Te3 phase has been formed after 1h of milling and there is no phase transition up to 10h of milling. HRTEM study also reveals the formation of single phase nanostructured Bi2Te3 phase. The DC (direct current) conductivities of 15min, 30min and 10h ball milled powders are measured within the temperature range of 359 to 633K. The electrical conductivity (σ) of Bi2Te3 indicates the semiconducting nature of the sample. There is no significant change of electrical conductivity of Bi2Te3 phase since its formation after 15min to 10h of milling, as there is no noticeable change in crystallite size.
Highlights
As fossil fuel resources are becoming exhausted, thermoelectric (TE) devices, as alternative power resources have found their applications in power generators or cooling devices 1,2
Microstructure and electrical characterization of thermoelectric nanocrystalline Bi2Te3 synthesized by mechanical alloying
After 1h of milling, Bi2Te3 phase formation has been completed with the disappearance of two minor phases
Summary
As fossil fuel resources are becoming exhausted, thermoelectric (TE) devices, as alternative power resources have found their applications in power generators or cooling devices 1,2. Reducing the crystallite size of polycrystalline TE materials to the nano-scale has resulted in a significant reduction of the lattice thermal conductivity and improvement in the figure of merit 6, 7. Most of these advances are related to the use of nanostructures due to thermal conductivity reduction 8, 9. The aim of the present research work is the production of nanostructured bismuth telluride thermoelectric material in a low-cost method For this purpose, we have employed the MA method to prepare nanocrystalline bismuth telluride alloy starting from an elemental powder mixture of Bi and Te at room temperature
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