الفهرس 
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Abstract
The current study has witnessed a successful synthesis of Bismuth Telluride
(Bi2Te3) by wet chemical method (water-based synthesis). selected parameters have
been studied involving the influence of reducing agents, such as L-ascobic acid and
sodium borohydride, chelating agent, which was Tris(hydroxyl methyl) amino methane
(Trizma) and surfactants such as Cetyl trimethyl ammonium bromide (CTAB) and
Ethylenediaminetetraacetic acid disodium salt (EDTA) in addition to the reaction time
of completion on Bi2Te3 performance.
The present research included physical and thermoelectric (TE) characterization
of the synthesized Bi2Te3 samples. The physical characterization incorporated X-ray
diffraction analysis (XRD), scanning electron microscope (SEM) and energy-dispersive
X-ray spectroscopy (EDX). Measurement of the TE parameters, as Seebeck coefficient,
electrical and thermal conductivities, was performed for TE characterization.
Synthesis of Bi2Te3 in presence of Trizma utilizing L- ascobic acid rather than
sodium borohydride was found to improve Bi2Te3 performance. Since, Bi2Te3
synthesized by L-ascobic acid resulted in smaller size and hence higher electrical
conductivity than that by sodium borohydride. However, this higher electrical
conductivity led to smaller Seebeck coefficient and hence reduced the figure of merit
(ZT) value less than that calculated for Bi2Te3 synthesized by sodium borohydride.
In addition, Trizma played a vital role in the formation of Bi2Te3 nanoparticles.
Since, it acted as a good chelating agent with Bi+3 ions for the synthesized Bi2Te3 either
by L-ascobic acid or sodium borohydride and hence enhanced Bi2Te3 performance.
Furthermore, it was concluded that CTAB had a great effect in the formation of
dispersed Bi2Te3 nanoparticles either by L-ascorbic acid or sodium borohydride. While
EDTA led to the formation of Bi2Te3 nanospheres of smaller size than the case of
absence of EDTA.