Preparation And Performance Optimization Of PbSe Thermoelectric Materials

Thermoelectric materials can realize conversion between heat energy and electric energy directly. Recently, thermoelectric materials appeal considerable investigation due to amount of advantages campared to the traditional generator, such as:noiselessness, pollution free, low maintenance etc.. PbSe, used in mediate temperature, is considered to be an excellent semiconductor. According to the reports, the thermoelectric figure merit of PbTe which belongs to the same main group compound with PbSe had been reached around 2, but reserves of Te in earth is very rare. However, the content of Se in the earth is 50 times more than that of Te. In addition, PbSe and PbTe have the similar crystal structure and electric structure, and the PbSe has higher melting temperature which could be applied at higher temperature. So PbSe as thermoelectric material was studied intensively.In this thesis, the bulk PbSe samples were fabricated by ball milling and hot pressing. The X-ray diffraction analysis and SEM were characterized and the thermoelectric parameters were measured. Ball milling time and hot pressing time. Parameters that influenced thermoelectric performance were investigated.First, we preceded a lot of experiment to analysis the influence of ball milling and hot pressing on the thermoelectric performance and optimize their processing time. X-ray diffraction demonstrated that the pure PbSe samples were obtained after optimizing.Second, the influence of the doped process on the thermoelectric parameters was investigated. Thermoelectric performance of PbSe was investigated by dopped with Al. The doped effects on the PbSe matrix were also investigated. The doped Al lead to the increase of electric conductivity and decrease of Seebeck coefficient and thermal conductivity. PbSe made by ball milling and hot pressing in out lab was p-type conduction which was different from other reports. It could be concluded that high-energy ball milling could bring a lot of atom defects, such as point defects and lattice strain etc..which are responsible for production mechanism of carrier.