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Solvothermal synthesis and thermoelectric properties of indium telluride nanostring-cluster hierarchical structures.

Tai G, Miao C, Wang Y, Bai Y, Zhang H, Guo W - Nanoscale Res Lett (2011)

Bottom Line: A simple solvothermal approach has been developed to successfully synthesize n-type α-In2Te3 thermoelectric nanomaterials.A diffusion-limited reaction mechanism was proposed to explain the formation of the hierarchical structures.The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures.PACS: 65.80.-g, 68.35.bg, 68.35.bt.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China. taiguoan@nuaa.edu.cn.

ABSTRACT
A simple solvothermal approach has been developed to successfully synthesize n-type α-In2Te3 thermoelectric nanomaterials. The nanostring-cluster hierarchical structures were prepared using In(NO3)3 and Na2TeO3 as the reactants in a mixed solvent of ethylenediamine and ethylene glycol at 200°C for 24 h. A diffusion-limited reaction mechanism was proposed to explain the formation of the hierarchical structures. The Seebeck coefficient of the bulk pellet pressed by the obtained samples exhibits 43% enhancement over that of the corresponding thin film at room temperature. The electrical conductivity of the bulk pellet is one to four orders of magnitude higher than that of the corresponding thin film or p-type bulk sample. The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures.PACS: 65.80.-g, 68.35.bg, 68.35.bt.

No MeSH data available.


FE-SEM images of the In2Te3 hierarchical structures prepared at 200°C for 24 h:(a) low magnification and (b) high magnification.
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Figure 2: FE-SEM images of the In2Te3 hierarchical structures prepared at 200°C for 24 h:(a) low magnification and (b) high magnification.

Mentions: The morphology and size of the as-synthesized products were characterized by FE-SEM on a Cu substrate. The FE-SEM images show a large number of hierarchical structures, each of which consists of arrays of small nanoplatelets which is similar to nanostring-cluster structure. Figure 2a shows a FE-SEM image of the In2Te3 hierarchical structures with diameter from 100 nm to 2 μm and length from several to over 100 μm, under a typically solvothermal reaction with In(NO3)3 and Na2TeO3 as the reactants, and EDA as the reductant and complexing agent at 200°C for 24 h. Figure 2b shows that a typically well-oriented nanoplatelet in the hierarchical structures possesses an edge length of approx. 700 nm and a thickness of approx. 150 nm. The phase purity and crystallographic structure of the products were determined by X-ray powder diffraction (XRD) with Cu Kα radiation. Figure 3a shows the transformation from t-Te nanowires to In2Te3 hierarchical structures occurred with increasing the reaction duration. As shown in Figure 3a, the as-synthesized In2Te3 hierarchical structures at 200°C for 24 h exhibited three broad peaks at 2θ = 25.02, 41.40, and 49.02, which were assignable to diffractions of the (511), (822), and (933) planes, respectively. In addition, five weak peaks at 2θ = 27.58, 28.92, 59.92, 66.02, and 75.46 were assignable to diffractions of the (440), (600), (1200), (993), and (1266), respectively. The diffraction peaks can be indexed to the purely fcc phase of In2Te3 (space group: F4\overline 3 m, no. 216) with lattice constants of a = b = c = 1.848 nm (JCPDS card: 33-1488). No other peaks from any other phases of indium telluride were detected. The crystal structure, as seen in Figure 3b, shows strong covalent bonding within each layer and a weak van der Waals force between the layers. Thus, the appearance of nanoplatelets on the wires is understandable due to the planar sheetlike nature of the building blocks. In other words, growth of the nanoplatelets is actually the outward embodiment of the internal crystal structure in this case.


Solvothermal synthesis and thermoelectric properties of indium telluride nanostring-cluster hierarchical structures.

Tai G, Miao C, Wang Y, Bai Y, Zhang H, Guo W - Nanoscale Res Lett (2011)

FE-SEM images of the In2Te3 hierarchical structures prepared at 200°C for 24 h:(a) low magnification and (b) high magnification.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211416&req=5

Figure 2: FE-SEM images of the In2Te3 hierarchical structures prepared at 200°C for 24 h:(a) low magnification and (b) high magnification.
Mentions: The morphology and size of the as-synthesized products were characterized by FE-SEM on a Cu substrate. The FE-SEM images show a large number of hierarchical structures, each of which consists of arrays of small nanoplatelets which is similar to nanostring-cluster structure. Figure 2a shows a FE-SEM image of the In2Te3 hierarchical structures with diameter from 100 nm to 2 μm and length from several to over 100 μm, under a typically solvothermal reaction with In(NO3)3 and Na2TeO3 as the reactants, and EDA as the reductant and complexing agent at 200°C for 24 h. Figure 2b shows that a typically well-oriented nanoplatelet in the hierarchical structures possesses an edge length of approx. 700 nm and a thickness of approx. 150 nm. The phase purity and crystallographic structure of the products were determined by X-ray powder diffraction (XRD) with Cu Kα radiation. Figure 3a shows the transformation from t-Te nanowires to In2Te3 hierarchical structures occurred with increasing the reaction duration. As shown in Figure 3a, the as-synthesized In2Te3 hierarchical structures at 200°C for 24 h exhibited three broad peaks at 2θ = 25.02, 41.40, and 49.02, which were assignable to diffractions of the (511), (822), and (933) planes, respectively. In addition, five weak peaks at 2θ = 27.58, 28.92, 59.92, 66.02, and 75.46 were assignable to diffractions of the (440), (600), (1200), (993), and (1266), respectively. The diffraction peaks can be indexed to the purely fcc phase of In2Te3 (space group: F4\overline 3 m, no. 216) with lattice constants of a = b = c = 1.848 nm (JCPDS card: 33-1488). No other peaks from any other phases of indium telluride were detected. The crystal structure, as seen in Figure 3b, shows strong covalent bonding within each layer and a weak van der Waals force between the layers. Thus, the appearance of nanoplatelets on the wires is understandable due to the planar sheetlike nature of the building blocks. In other words, growth of the nanoplatelets is actually the outward embodiment of the internal crystal structure in this case.

Bottom Line: A simple solvothermal approach has been developed to successfully synthesize n-type α-In2Te3 thermoelectric nanomaterials.A diffusion-limited reaction mechanism was proposed to explain the formation of the hierarchical structures.The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures.PACS: 65.80.-g, 68.35.bg, 68.35.bt.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China. taiguoan@nuaa.edu.cn.

ABSTRACT
A simple solvothermal approach has been developed to successfully synthesize n-type α-In2Te3 thermoelectric nanomaterials. The nanostring-cluster hierarchical structures were prepared using In(NO3)3 and Na2TeO3 as the reactants in a mixed solvent of ethylenediamine and ethylene glycol at 200°C for 24 h. A diffusion-limited reaction mechanism was proposed to explain the formation of the hierarchical structures. The Seebeck coefficient of the bulk pellet pressed by the obtained samples exhibits 43% enhancement over that of the corresponding thin film at room temperature. The electrical conductivity of the bulk pellet is one to four orders of magnitude higher than that of the corresponding thin film or p-type bulk sample. The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures.PACS: 65.80.-g, 68.35.bg, 68.35.bt.

No MeSH data available.