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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.


Powder X-ray diffraction patterns of the as-synthesized samples with different temperatures and durations: (a) 160°C for 24 h, (b) 160°C for 48 h, and (c) 220°C for 24 h.
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Figure 7: Powder X-ray diffraction patterns of the as-synthesized samples with different temperatures and durations: (a) 160°C for 24 h, (b) 160°C for 48 h, and (c) 220°C for 24 h.

Mentions: To understand the growth process of the In2Te3 hierarchical structures, the effects of the reaction duration, temperature, volume ratio of EDA/EG, concentration of In(NO3)3 on the resulting products were systematically investigated (Figure 3, 4, 5, 6 and 7). (1) Time-dependent experiments in EDA at 200°C were performed to gain insight into the formation process of the hierarchical structures. The obtained product was nearly pure hexagonal t-Te nanowires within 3 h at 200°C (Figures 3a and 5a). Some flower-like In2Te3 nanoparticles appeared on the surface of the nanowires when the reaction duration was increased to 6 h (Figure 5b). Prolonging the reaction duration to 12 h, the same results as that of 6 h were produced (Figures 3a and 5c). Extending the reaction duration to 18 h caused smooth nanowires to grow into the wires with rough surface composed of nanoparticles (Figure 5d). The above results show that the intermediate morphology composed of the Te nanowires and In2Te3 nanoplates can be produced in 6 and 12 h. Well-defined In2Te3 hierarchical structures were obtained when prolonging the reaction duration up to 24 h (Figures 2 and 3a). Besides the ordered nanoplates, some nanowires were detected in the nanostructure, which suggests that the nanoplates nucleate and grow out of the nanowires. (2) When aged at 160°C over 48 h, the nearly pure hexagonal t-Te nanowires were only formed (Figures 6b and 7b), but the FE-SEM images (Figure 6c) shows that some flower-like In2Te3 nanoparticles appeared on the surface of the nanowires. When aged at 220°C over 24 h, the mixture of nanowires and nanoplates was produced, as shown in Figure 6d. Figure 7c exhibits the mixture mainly composed of t-Te nanowires. The indexed Te peaks are in good agreement with the standard literature data (JCPDF card number: 36-1452) in Figure 7. (3) The volume ratio of EDA/EG also plays an important role in structure and phase control of the resulting products (not shown). When pure EDA or EG was used in the reaction, pure cubic In2Te3 could not be got (not shown). Additionally, when the volume ratios of EDA/EG were 1:2, 1:12, or 1:16, pure cubic In2Te3 could also not be obtained. (4) When the other conditions remained the same, the concentration of In(NO3)3 was 13.25 mM, the obtained products were a mixture of In2Te3 and t-Te (not shown).


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)

Powder X-ray diffraction patterns of the as-synthesized samples with different temperatures and durations: (a) 160°C for 24 h, (b) 160°C for 48 h, and (c) 220°C for 24 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Powder X-ray diffraction patterns of the as-synthesized samples with different temperatures and durations: (a) 160°C for 24 h, (b) 160°C for 48 h, and (c) 220°C for 24 h.
Mentions: To understand the growth process of the In2Te3 hierarchical structures, the effects of the reaction duration, temperature, volume ratio of EDA/EG, concentration of In(NO3)3 on the resulting products were systematically investigated (Figure 3, 4, 5, 6 and 7). (1) Time-dependent experiments in EDA at 200°C were performed to gain insight into the formation process of the hierarchical structures. The obtained product was nearly pure hexagonal t-Te nanowires within 3 h at 200°C (Figures 3a and 5a). Some flower-like In2Te3 nanoparticles appeared on the surface of the nanowires when the reaction duration was increased to 6 h (Figure 5b). Prolonging the reaction duration to 12 h, the same results as that of 6 h were produced (Figures 3a and 5c). Extending the reaction duration to 18 h caused smooth nanowires to grow into the wires with rough surface composed of nanoparticles (Figure 5d). The above results show that the intermediate morphology composed of the Te nanowires and In2Te3 nanoplates can be produced in 6 and 12 h. Well-defined In2Te3 hierarchical structures were obtained when prolonging the reaction duration up to 24 h (Figures 2 and 3a). Besides the ordered nanoplates, some nanowires were detected in the nanostructure, which suggests that the nanoplates nucleate and grow out of the nanowires. (2) When aged at 160°C over 48 h, the nearly pure hexagonal t-Te nanowires were only formed (Figures 6b and 7b), but the FE-SEM images (Figure 6c) shows that some flower-like In2Te3 nanoparticles appeared on the surface of the nanowires. When aged at 220°C over 24 h, the mixture of nanowires and nanoplates was produced, as shown in Figure 6d. Figure 7c exhibits the mixture mainly composed of t-Te nanowires. The indexed Te peaks are in good agreement with the standard literature data (JCPDF card number: 36-1452) in Figure 7. (3) The volume ratio of EDA/EG also plays an important role in structure and phase control of the resulting products (not shown). When pure EDA or EG was used in the reaction, pure cubic In2Te3 could not be got (not shown). Additionally, when the volume ratios of EDA/EG were 1:2, 1:12, or 1:16, pure cubic In2Te3 could also not be obtained. (4) When the other conditions remained the same, the concentration of In(NO3)3 was 13.25 mM, the obtained products were a mixture of In2Te3 and t-Te (not shown).

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.