Preparation And Properties Of Ag₂Te/Bi₂Te₃ Thermoelectric Nanomaterils And Their Composites

Nowadays, with rapid development of economy and the increasingly shortage of energy, thermoelectric material which is a kind of clean and reproducible energy material is attracting widespread interest. The method of improve the thermoelectric properties makes the technology become the bottleneck of its being used in our daily life. Nano-composite technology could improve the thermoelectric properties of the thermoelectric material. In recent years, many scholars publish their new research results of high-powered nano composite thermoelectric material. In this paper, using hydrothermal(solvothermal) the one-dimensional Ag₂Te nanowires and Bi₂Te₃ are prepared, and the precursors are tested on token and electrology characteristic. We had a research on the double hydrothermal and mechanical mixed methods synthesis of Ag₂Te, Bi₂Te₃ and compounds with the first two precursors.The pure phase of precursors the Ag₂Te is prepared; via the SEM, TEM et al, it is revealed that the Ag₂Te is the nano wire with the length of dozens of micron and the diameter of 200-300nm. After testing and analyzing its performance, the result reveals that the conductivity of Ag₂Te is higher than the result that mentioned in the documents. Because of the phase variation, Seebeck coefficient's singe changed, which indicates that Ag₂Te changed from n-type semiconductor into p-type during the temperature-rise period.Having explored the manufacture craft of, we investigate the elements that might influence the appearance of pure phase Bi₂Te₃. The elements as viscosity and the surface tension of the menstruum alike all will influence the process of crystal nucleation and growth. With higher viscosity the crystal size is uniform , and will grow slower, which is can help the crystal growing into a structure which is more homogeneous. The coordination agent could adhere on some crystal face selectively, thus it influences the direction of the crystal's growth and created different appearance of it. The best manufacture craft of producing flower-like structure Bi₂Te₃ is decided, so we can analyze the function of the reactants during the growth. Through the analysis we briefly put forward the growth mechanism of the Bi₂Te₃'flower-like structure is dissolved-recrystallized.Adopting the mechanical mixing method and secondary hydro-thermal method, we can manufacture Ag₂Te/Bi₂Te₃ nano composite material respectively. The electrology performance test reveals that mechanical mixing method can help with promote the thermoelectric properties of the material. While the Ag₂Te/Bi₂Te₃ nano composite material created through secondary hydro-thermal method gains a obvious promotion on electrical conductivity, which reaches 270S cm-1 at the highest-level, and that is much higher than the electrical conductivity of precursor.