Research On Properties Of N-type Bi₂Te₃ Based Thermoelectric Fiber

Thermoelectric materials can realize the direct conversion of heat and electric energy,so it is expected to turn low-quality waste heat energy into treasure,which has great application potential in new energy and smart wearables.However,the application of thermoelectric materials is limited due to the problems of brittleness and low thermoelectric performance.Bi₂Te₃ thermoelectric material has excellent thermoelectric properties near room temperature,and is the only thermoelectric material system that has been commercialized on a large scale.However,due to the strong anisotropy of n-type Bi₂Te₃ thermoelectric material,its thermoelectric properties are at a low level.In order to solve these problems,a core-clad N-type Bi₂Te₃ thermoelectric fiber was developed by the core melting method in this project.The preferred orientation of the crystal was promoted by low dimensional and nanocrystallization to improve the thermoelectric properties and toughness of the material.The main research contents and results are as follows:(1)Thermoelectric fiber of Bi₂Te_3-xSe_x core was prepared by core melting method.Combined with scanning electron microscopy,X-ray diffraction test,Raman spectroscopy and thermoelectric property test,the influence of element segregation and crystal defects in the thermoelectric fiber on the thermoelectric property was studied,and the experimental process was improved.(2)Annealing and Bridgmann methods were used to improve the macroscopic defects,and the defect improvement and preferred orientation of the treated fibers were discussed.The effects of different heat treatment methods and treatment systems on the preferred orientation and thermoelectric properties of Bi₂Te_3-xSe_x fibers were analyzed.The best technological system of heat treatment of thermoelectric fiber is summarized.(3)The experimental process was further optimized to prepare the thermoelectric fiber with excellent thermoelectric properties.Combined with X-ray diffraction test,the preferred orientation of the fiber was analyzed,and the thermoelectric properties of the fiber were characterized.The thermoelectric refrigeration device was built by using the self-made thermoelectric fiber,and its refrigeration effect was demonstrated.