A First-principles Study On Structure Of Doped PbTe-based Materials

Facing the worldwide energy crisis, such as natural gas and oil, environmental pollution which seriously threaten the survival and development of mankind, researchers from all over the world are working at exploring alternatives to fossil energy, In order to solve energy crisis and maintain the sustainable development, human being have been looking for new forms of energy to meet the needs of the rapid increase of energy and environmental protection. Thermoelectric materials in the paper are kind of functional material which can convert heat to electricity directly or reversely, which are prospect using as the thermoelectric generators and cooling devices.However, the thermoelectric material at present has a low conversion efficiency, According to reports, the conversion efficiency of thermoelectric equipment only is10%lower than that of the engine power efficiency, which can achieve35%or so, which confines it greatly from being used extensively in the national economy in turn, the property of thermoelectric material can be measured by the dimensionless figure of merit-ZT, optimal ZT values limit is not found from the perspective of theory. Though the ZT values of the thermoelectric material being studied are low which cannot satisfy the need of practical application, the thermoelectric materials are widely prospect of development in the longer term. If the ZT values of the thermoelectric material being studied are higher than3, the traditional refrigeration and power generation way can be replaced with the latest thermoelectric way.The nanocomposites (PbTe)(1-X)(AgSbTe2)x(x～0.05) exhibit very high TE efficiency measured by the figure of merit parameter ZT～1.7at800K. It has been recently recognized that the presence of nanoprecipitates is likely key to producing high ZT values. A prerequisite to understanding TE properties is an accurate determination of the micro structure of these complex nanocomposites, especially the atomic arrangement and nucleation mechanism. In this paper, studying for three different PbTe-based materials, we find that the structure rule of one kind of material is generally consistent with the prediction of Coulomb interaction potential model. The other one is the other way round, and the reason can be said as the energy caused by lattice relaxation is greater than Coulomb potential energy.