Lead-free SnTe with naturally non-stoichiometric vacancies has a limited thermoelectric performance due to a deviated carrier concentration from the optimum.In this paper,we experimentally demonstrated that Gd with+3 ...Lead-free SnTe with naturally non-stoichiometric vacancies has a limited thermoelectric performance due to a deviated carrier concentration from the optimum.In this paper,we experimentally demonstrated that Gd with+3 valence state as a novel n-type dopant is an effective solution for reducing carrier concentration in SnTe.A lowest value of 7.6×10^(18) cm^(−3) has been achieved.Yet with the involvement of Gd doping,the slightly modified band structure requires a further Sndeficiency compensation to enhance the overall figure of merit zT.As a consequence,in the specific sample Sn_(0.91)Gd_(0.07)Te,we successfully achieved a low lattice thermal conductivity of 0.8 W/(m K)due to the high doping level and an improved zT approaching 0.8 at 850 K.展开更多
Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10^(20)–10^(21)cm^(−3)and an excessively high lattice thermal conductivity.However,the high carri...Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10^(20)–10^(21)cm^(−3)and an excessively high lattice thermal conductivity.However,the high carrier concentration and lattice thermal conductivity observed in SnTe are not solely attributable to the presence of numerous intrinsic tin vacancies and a simple crystal structure.Additionally,the oxides formed through the oxidation of Sn and SnTe exert a partial influence on these properties.In this study,by pretreating the raw Sn material and isolating it from oxygen during preparation,we achieve a significant improvement in the thermoelectric performance of binary SnTe at high temperatures,with a peak ZT of approximately 0.83 at 800 K.This approach effectively reduces the content of SnO_(2)in the matrix,enhancing the electrical and thermal transport properties of the samples.Specifically,the high-thermal conductivity of SnO_(2)facilitates the formation of channels at grain boundaries that are more conducive to heat transfer,while its poor electrical conductivity and Seebeck coefficient diminish the intrinsic electrical transport behavior of SnTe.The removal of SnO_(2)reflects the true thermoelectric performance of SnTe,making the samples prepared by this method stand out compared to other reported binary SnTe materials.展开更多
Thermoelectric materials possess tremendous potential in energy regeneration owing to their capacity to produce power directly from heat.SnTe,a lead-free compound,is a prospective thermoelectric material.However,becau...Thermoelectric materials possess tremendous potential in energy regeneration owing to their capacity to produce power directly from heat.SnTe,a lead-free compound,is a prospective thermoelectric material.However,because of its elevated thermal conductivity,the thermoelectric performance of undoped SnTe remains at a low level.In this work,we induce ternary compounds CuFeS_(2) into the SnTe matrix by ball milling.We observe the decomposition of CuFeS_(2),which decomposes into FeS,Cu_(2)S,and other binary compounds.These newly generated binary compounds form micropores and secondary phases in the matrix.Combined with the natural grain boundaries in the polycrystal,they form all-scale hierarchical structures within the material,resulting in reduced lattice thermal conductivity.Overall,the produced SnTe+2 wt%CuFeS_(2) composites show the peak dimensionless figure of merit(ZT)up to 0.33 at 673 K,an increase of~100%compared to the undoped SnTe.展开更多
Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound,despite the realization of n-type SnTe being a gre...Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound,despite the realization of n-type SnTe being a great challenge.Herein,Cl as a donor dopant can effectively regulate the position of Fermi level in Sn_(0.6)Pb_(0.4)Te matrix and successfully achieve the n-type transport behavior in SnTe.An outstanding power factor of~14.7μW·cm^(-1)·K^(-2) at 300 K was obtained for Cl-doped Sn_(0.6)Pb_(0.4)Te sample.By combining the experimental analysis with theoretical calculations,the transport properties of n-type SnTe thermoelectrics doped with different halogen dopants(Cl,Br,and I)were then systematically investigated and estimated.The results demonstrated that Br and I had better doping efficiencies compared with Cl,which contributed to the well-optimized carrier concentrations of~1.03×10^(19)and~1.11×10^(19)cm^(-3)at 300 K,respectively.The improved n-type carrier concentrations effectively lead to the significant enhancement on the thermoelectric performance of n-type SnTe.Our study further promoted the experimental progress and deep interpretation of the transport features in n-type SnTe thermoelectrics.The present results could also be crucial for the development of n-type counterparts for SnTe-based thermoelectric devices.展开更多
基金sponsored by the National Natural Science Foundation of China(52371193,52001231,and 52272006)the Shanghai Academic Research Leader(23XD1421200)+2 种基金the Shanghai Rising-Star Program(23QA1403900)the Chenguang Program supported by Shanghai Education Development Foundation&Shanghai Municipal Education Commission,the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions(TP2022122)the Shanghai Oriental Talented Youth Project,Space Application System of China Manned Space Program(KJZ-YY-NCL-0405).
文摘Lead-free SnTe with naturally non-stoichiometric vacancies has a limited thermoelectric performance due to a deviated carrier concentration from the optimum.In this paper,we experimentally demonstrated that Gd with+3 valence state as a novel n-type dopant is an effective solution for reducing carrier concentration in SnTe.A lowest value of 7.6×10^(18) cm^(−3) has been achieved.Yet with the involvement of Gd doping,the slightly modified band structure requires a further Sndeficiency compensation to enhance the overall figure of merit zT.As a consequence,in the specific sample Sn_(0.91)Gd_(0.07)Te,we successfully achieved a low lattice thermal conductivity of 0.8 W/(m K)due to the high doping level and an improved zT approaching 0.8 at 850 K.
基金supported by the National Natural Science Foundation of China(Grant No.52371235)the National Natural Science Foundation of China(Grant No.52171221).
文摘Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10^(20)–10^(21)cm^(−3)and an excessively high lattice thermal conductivity.However,the high carrier concentration and lattice thermal conductivity observed in SnTe are not solely attributable to the presence of numerous intrinsic tin vacancies and a simple crystal structure.Additionally,the oxides formed through the oxidation of Sn and SnTe exert a partial influence on these properties.In this study,by pretreating the raw Sn material and isolating it from oxygen during preparation,we achieve a significant improvement in the thermoelectric performance of binary SnTe at high temperatures,with a peak ZT of approximately 0.83 at 800 K.This approach effectively reduces the content of SnO_(2)in the matrix,enhancing the electrical and thermal transport properties of the samples.Specifically,the high-thermal conductivity of SnO_(2)facilitates the formation of channels at grain boundaries that are more conducive to heat transfer,while its poor electrical conductivity and Seebeck coefficient diminish the intrinsic electrical transport behavior of SnTe.The removal of SnO_(2)reflects the true thermoelectric performance of SnTe,making the samples prepared by this method stand out compared to other reported binary SnTe materials.
基金supported by the National Science Fund for Distinguished Young Scholars(51925101)the National Natural Science Foundation of China(52250090,52371208,52002042,51772012,51571007,12374023,and 52171216)+2 种基金the Beijing Natural Science Foundation(JQ18004)the 111 Project(B17002)the Tencent Xplorer Prize and National Key Research and Development Program of China(2023YFB3809400).
文摘Thermoelectric materials possess tremendous potential in energy regeneration owing to their capacity to produce power directly from heat.SnTe,a lead-free compound,is a prospective thermoelectric material.However,because of its elevated thermal conductivity,the thermoelectric performance of undoped SnTe remains at a low level.In this work,we induce ternary compounds CuFeS_(2) into the SnTe matrix by ball milling.We observe the decomposition of CuFeS_(2),which decomposes into FeS,Cu_(2)S,and other binary compounds.These newly generated binary compounds form micropores and secondary phases in the matrix.Combined with the natural grain boundaries in the polycrystal,they form all-scale hierarchical structures within the material,resulting in reduced lattice thermal conductivity.Overall,the produced SnTe+2 wt%CuFeS_(2) composites show the peak dimensionless figure of merit(ZT)up to 0.33 at 673 K,an increase of~100%compared to the undoped SnTe.
基金supported by the National Natural Science Foundation of China(No.52002042)the National Postdoctoral Program for Innovative Talents(No.BX20200028)+3 种基金the National Key Research and Development Program of China(No.2018YFA0702100)China Postdoctoral Science Foundation(No.2021M690280)the Natural Science Foundation of Chongqing,China(No.cstc2019jcyj-msxmX0554)the support from the National Science Fund for Distinguished Young Scholars(No.51925101)。
文摘Recent theoretical predictions and experimental findings on the transport properties of n-type SnTe have triggered extensive researches on this simple binary compound,despite the realization of n-type SnTe being a great challenge.Herein,Cl as a donor dopant can effectively regulate the position of Fermi level in Sn_(0.6)Pb_(0.4)Te matrix and successfully achieve the n-type transport behavior in SnTe.An outstanding power factor of~14.7μW·cm^(-1)·K^(-2) at 300 K was obtained for Cl-doped Sn_(0.6)Pb_(0.4)Te sample.By combining the experimental analysis with theoretical calculations,the transport properties of n-type SnTe thermoelectrics doped with different halogen dopants(Cl,Br,and I)were then systematically investigated and estimated.The results demonstrated that Br and I had better doping efficiencies compared with Cl,which contributed to the well-optimized carrier concentrations of~1.03×10^(19)and~1.11×10^(19)cm^(-3)at 300 K,respectively.The improved n-type carrier concentrations effectively lead to the significant enhancement on the thermoelectric performance of n-type SnTe.Our study further promoted the experimental progress and deep interpretation of the transport features in n-type SnTe thermoelectrics.The present results could also be crucial for the development of n-type counterparts for SnTe-based thermoelectric devices.
