摘要
为探索性能更优的Mg基热电材料,本文基于第一性原理,结合分子动力学从能带结构和态密度、马利肯键布居以及载流子相对质量等微观层面研究Mg_(2)X(X=Sn,Pb)和Mg_(3)X_(2)(X=Sb,Bi)在基态、施加温度场和压力下的电子结构和热电性质.研究表明:Mg_(2)Sn,Mg_(2)Pb,Mg_(3)Sb_(2)和Mg_(3)Bi_(2)分别在温度为800 K,750 K,700 K和800 K左右时能隙最小,态密度峰值和载流子相对质量达到峰值,键布居数最小,热电性能最优;Mg_(2)Sn和Mg_(2)Pb在低压1~4 GPa时热电性能更理想,Mg_(3)Sb_(2)和Mg_(3)Bi_(2)在高压4~8 GPa时热电性能更理想,微观特征均表现为导带底下降接近价带,同时键布居数减小,载流子相对质量增加.
In the background of the carbon peak and neutrality goals,the energy and power industry is facing opportunities and challenges.With the rapid development of the global industrialization process,energy crisis and environmental pollution have become problems that cannot be ignored in every country.In order to reduce the energy loss in the form of waste heat,it is imperative to vigorously develop and promote high-efficiency thermoelectric power generation technology.As a new type of environmentally friendly material,thermoelectric materials have broad application prospects.Existing Mg-typed thermoelectric materials have received widespread attention due to their low prices and good environmental coordination,but their low thermoelectric conversion efficiency limits their further application,so it is of great significance to explore ways to improve thermoelectric conversion efficiency.In order to explore better performance of Mg-typed thermoelectric materials,based on first-principles calculations and molecular dynamics simulations,we study the energy band structure,the density of states,covalent bond population and the carrier relative mass of Mg_(2)X(X=Sn,Pb)and Mg_(3)X_(2)(X=Sb,Bi)in the ground state,different temperature and pressure.The results show that Mg_(2)Sn,Mg_(2)Pb,Mg_(3)Sb2 and Mg_(3)Bi_(2)have better thermoelectric performance at 800 K,750 K,700 K,and 800 K.They have the smallest energy gap values and the peak density of states,the carrier relative mass reach the peak and the bond population is the smallest.Compared with the highest bond population,it has decreased by 34%,31%,65%,and 73%.Mg_(2)Sn and Mg_(2)Pb have better thermoelectric performance at low pressure of 1~4 GPa,the bottom of the conduction band drops substantially close to the valence band,the bond population decreases by 31%and 26%compared with the high pressure,and the carrier relative mass increases,which is 1.15 times and 1.18 times that of the high pressure state.Mg_(3)Sb2 and Mg_(3)Bi_(2)have better thermoelectric performance at high pressure of 4~8 GPa.The bottom of the conduction band drops substantially close to the valence band and merges with the top of the valence band.At the same time,the bond population is reduced,which is 31%and 41%lower than the low pressure.The carrier relative mass increases,which is 1.12 times and 1.13 times that of the low pressure state.It provides a technical reference for further research on the performance optimization of Mg-typed thermoelectric materials,and also provides a new research method for improving the thermoelectric conversion efficiency of thermoelectric materials.
作者
王成江
祝梦雅
张婧
WANG Cheng-jiang;ZHU Meng-ya;ZHANG Jing(College of Electrical Engineering&New Energy,China Three Gorges University,Yichang 443002,China)
出处
《分子科学学报》
CAS
北大核心
2022年第2期154-164,共11页
Journal of Molecular Science
基金
国家自然科学基金重点项目(51577105)。
