Preparation And Performance Of Bi₂Te₃Thermoelectric Materia

Thermoelectric material is a new semiconductor which can change heat and electrical energy, It was widely applicated, Especially in TE cooling devices and power generators. Bi2Te3is the best thermoelectric material, but ZT≈1,and its conversion efficiency is limited. Solvent thermal is a mainly method in synthesizing Bi2Te3.Its operation is simple, it is easy to control reaction temperature and reaction time, getting purity Bi2Te3, lower energy and so on.Changing the mainly parameters, synthesing Bi2Te3with different morphology with solvethermal method, Combined with XRD, SEM and TEM etc, charactering the composition and microstructure of Bi2Te3power, discuss the synthetic processes of Bi2Te3.Then, made Bi2Te3bulk for analysising thermalelectric and mechanical properties. The main content as follows:(1) Setting DMF as solvent, PH=12.5, PEG-4000as additions in solvethermal method, we can get Bi2Te3nanoflake with obvious orientation and hexagonal lamellar polycrystalline. The hexagonal diameter is about100nm and the thick is30nm.(2) Setting DMF as solvent, PH=12.5, PVP-K30as additions in solvethermal method, The solution was maintained at180℃for48h. we can get Bi2Te3nanoflake whicn is hexagonal lamellar polycrystalline with no obvious orientation. The hexagonal diameter is larger than100nm.(3) Changing the process parameters, such as reaction solvent, PH,additions.Discussing the effection on different products in solvethermal method.we found different solvent, PH,and additions has a big effect on the composition and microstructure of Bi2Te3power.(4) Discussing the synthetic process in Bi2Te3reaction.Finished the experiment without reducing agent,and Experiments with different reaction time, synthesis different products.Analysising the effections of reducing agent and reaction time.The reactions began with the reducing agent added. The main reaction is reducted Bi at the beginning, and then, the reaction of synthesing Bi2Te3included atom reaction and ion reaction, until the processing end.(5) Analysising the performance of Bi2Te3bulk. Testing its thermal conductivity, electrical conductivity, seebeck coefficient. The Bi2Te3bulk with obvious orientation and hexagonal lamellar polycrystalline has a better thermoelectric performance at423K. Then testing the HV of Bi2Te3bulk, it is132.5MPa. So the brittle of Bi2Te3is low, It is much more stable and reliable.