Fabrication and Characterization of Electrodeposited Bismuth Telluride Films and Nanowires

Abstract

To elucidate low-dimensional effects on thermoelectric materials, bismuth telluride film and nanowires array were fabricated by potentiostatically electrodeposition. Both materials are slightly Te-rich, n-type Bi2Te3, exhibiting preferred orientation in rhombohedral strcture. For both the Seebeck coefficient S ≈ −70 μV/K at 300 K decreases linearly with decreasing temperature, showing a diffusive nature of current flow. The temperature dependence of resistivity (=1/σ) of nanowires obtained from the data of a nanowires array and a single-nanowire reveals a better electric conductivity than that of the bulk. By coupling temperature-dependent thermal diffusivity and heat capacity data with a modified effective medium theory, a thermal conductivity κ of 0.75 W/(m K) was obtained at 300 K. The ZT was calculated to be 0.45 at 300 K and 0.9 at 350 K for Bi2Te3 nanowires.

Characterization of electrodeposited bismuth–tellurium nanowires and nanotubes

“…They also found that below a temperature of 440 K, Bi 2 Te 3 nanowires exhibited semiconducting behavior. A recent study by Chen et al [34] reported a negative Seebeck coefficient value of À65 lV K À1 at 300 K for Bi 2 Te 3 nanowires grown by potentiostatic electrodeposition within the pores of alumina template.…”

Individual thermoelectric properties of electrodeposited bismuth telluride nanowires in polycarbonate membranes

“…Previously, significant improvements of ZT values were reported for nanostructured bulk alloys [7], nanoinclusions [8], nanocomposites [9], and thin-film superlattices [10,11]. Moreover, many different growth techniques have been explored to produce Bi 2 Te 3 materials, including vapor-phase techniques [12][13], on-film formation of nanowires (OFF-ON) [14][15][16], and electrochemical deposition [17][18][19][20][21].…”

Fabrication, Characterization and Thermal Properties of Nanowires

“…Extra Te may be situated as substitution to Bi sites or at interstitial sites. They may also be in grain boundaries, but not enough to be observed in XRD as impurity phase (Chen et al, 2010). Meanwhile, all the XRD patterns of these nanowires array can be indexed to rhombohedral structure, and confirming their single-phase purity.…”

“…(1) According to the above conclusions, a series of Bi 2 Te 3 nanowires were electrodeposited potentiostatically at -150 mV by filling nanoporous membrane in 1 M HNO 3 solution containing different Bi/ Te ratio to find the optimal deposition condition (Chen et al, 2010 (Rowe, 1995). Therefore, this parameter was selected for the preparation of Bi 2 Te 3 nanowires.…”

“…The four wires of thermocouples can also be employed for electrical conductivity measurement of semi-four probe method. The schematic setup is shown in Fig. 11 (Chen et al, 2010). For thermal conductivity measurements, as the specimen size is larger than 6 mm in diameter, then it generally can be accomplished using laser flash setup of thermal diffusivity and calorimeter of specific heat.…”