Binary Cu-based chalcogenide thermoelectric materials have attracted a great deal of attention due to their outstanding physical properties and fascinating phase sequence.However,the relatively low figure of merit z T...Binary Cu-based chalcogenide thermoelectric materials have attracted a great deal of attention due to their outstanding physical properties and fascinating phase sequence.However,the relatively low figure of merit z T restricts their practical applications in power generation.A general approach to enhancing z T value is to produce nanostructured grains,while one disadvantage of such a method is the expansion of grain size in heating-up process.Here,we report a prominent improvement of z T in Cu2Te（0.2）Se（0.8）,which is several times larger than that of the matrix.This significant enhancement in thermoelectric performance is attributed to the formation of abundant porosity via cold press.These pores with nano-to micrometer size can manipulate phonon transport simultaneously,resulting in an apparent suppression of thermal conductivity.Moreover,the Se substitution triggers a rapid promotion of power factor,which compensates for the reduction of electrical properties due to carriers scattering by pores.Our strategy of porosity engineering by phonon scattering can also be highly applicable in enhancing the performances of other thermoelectric systems.展开更多
Thermoelectric(TE)performance of polycrystalline stannous selenide(SnSe)has been remarkably promoted by the strategies of energy band,defect engineering,etc.However,due to the intrinsic insufficiencies of phonon scatt...Thermoelectric(TE)performance of polycrystalline stannous selenide(SnSe)has been remarkably promoted by the strategies of energy band,defect engineering,etc.However,due to the intrinsic insufficiencies of phonon scattering and carrier concentration,it is hard to simultaneously realize the regulations of electrical and thermal transport properties by one simple approach.Herein,we develop Cu and Ce co-doping strategy that can not only greatly reduce lattice thermal conductivity but also improve the electrical transport properties.In this strategy,the incorporated Cu and Ce atoms could induce high-density SnSe_(2) nanoprecipitation arrays on the surface of SnSe microplate,and produce dopant atom point defects and dislocations in its interior,which form multi-scale phonon scattering synergy,thereby presenting an ultralow thermal conductivity of 0.275 W·m^(−1)·K^(−1) at 786 K.Meanwhile,density functional theory(DFT)calculations,carrier concentration,and mobility testing reveal that more extra hole carriers and lower conducting carrier scattering generate after Cu and Ce co-doping,thereby improving the electrical conductivity.The co-doped Sn_(0.98)Cu_(0.01)Ce_(0.01)Se bulk exhibits an excellent ZT value up to~1.2 at 786 K and a high average ZT value of 0.67 from 300 to 786 K.This work provides a simple and convenient strategy of enhancing the TE performance of polycrystalline SnSe.展开更多
The argyrodite compounds(2 A(12)/B X6 m n n^(m+)+--(Am+=Li^(+),Cu^(+),and Ag^(+);Bn^(+)=Ga^(3+),Si^(4+),Ge^(4+),Sn^(4+),P^(5+),and As^(5+);and X^(2−)=S^(2−),Se^(2−),or Te^(2−)))have attracted great attention as excell...The argyrodite compounds(2 A(12)/B X6 m n n^(m+)+--(Am+=Li^(+),Cu^(+),and Ag^(+);Bn^(+)=Ga^(3+),Si^(4+),Ge^(4+),Sn^(4+),P^(5+),and As^(5+);and X^(2−)=S^(2−),Se^(2−),or Te^(2−)))have attracted great attention as excellent thermoelectric(TE)materials due to their extremely low lattice thermal conductivity(κl).Among them,Ag_(8)SnSe_(6)-based TE materials have high potential for TE applications.However,the pristine Ag_(8)SnSe_(6)materials have low carrier concentration(<1017 cm^(−3)),resulting in low power factors.In this study,a hydrothermal method was used to synthesize Ag_(8)SnSe_(6)with high purity,and the introduction of SnBr_(2)into the pristine Ag_(8)SnSe_(6)powders has been used to simultaneously increase the power factor and decrease the thermal conductivity(κ).On the one hand,a portion of the Br−ions acted as electrons to increase the carrier concentration,increasing the power factor to a value of~698 mW·m^(−1)·K^(−2)at 736 K.On the other hand,some of the dislocations and nanoprecipitates(SnBr_(2))were generated,resulting in a decrease ofκl(~0.13 W·m^(−1)·K^(−1))at 578 K.As a result,the zT value reaches~1.42 at 735 K for the sample Ag8Sn1.03Se5.94Br0.06,nearly 30%enhancement in contrast with that of the pristine sample(~1.09).The strategy of synergistic manipulation of carrier concentration and microstructure by introducing halogen compounds could be applied to the argyrodite compounds to improve the TE properties.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51771126 and 11774247)the Youth Foundation of Science and Technology Department of Sichuan Province,China(Grant No.2016JQ0051)+2 种基金Sichuan University Outstanding Young Scholars Research Funding(Grant No.2015SCU04A20)the World First-Class University Construction Fundingthe Fundamental and Frontier Research Project in Chongqing(Grant No.CSTC2015JCYJBX0026)
文摘Binary Cu-based chalcogenide thermoelectric materials have attracted a great deal of attention due to their outstanding physical properties and fascinating phase sequence.However,the relatively low figure of merit z T restricts their practical applications in power generation.A general approach to enhancing z T value is to produce nanostructured grains,while one disadvantage of such a method is the expansion of grain size in heating-up process.Here,we report a prominent improvement of z T in Cu2Te（0.2）Se（0.8）,which is several times larger than that of the matrix.This significant enhancement in thermoelectric performance is attributed to the formation of abundant porosity via cold press.These pores with nano-to micrometer size can manipulate phonon transport simultaneously,resulting in an apparent suppression of thermal conductivity.Moreover,the Se substitution triggers a rapid promotion of power factor,which compensates for the reduction of electrical properties due to carriers scattering by pores.Our strategy of porosity engineering by phonon scattering can also be highly applicable in enhancing the performances of other thermoelectric systems.
基金support of the National Natural Science Foundation of China(Grant Nos.51702193 and 51502165)the Natural Science Basic Research Program of Shaanxi(Grant No.2022JM-202)+3 种基金the Shaanxi Provincial Education Department Serves Local Scientific Research Plan(Grant No.20JC008)the General Project in Industrial Area of Shaanxi Province(Grant No.2020GY281)the Natural Science Foundation of Shaanxi Provincial Department of Education(Grant No.20JK0525)the Scientific Research Fund of Shaanxi University of Science&Technology(Grant Nos.BJ16-20 and BJ16-21).
文摘Thermoelectric(TE)performance of polycrystalline stannous selenide(SnSe)has been remarkably promoted by the strategies of energy band,defect engineering,etc.However,due to the intrinsic insufficiencies of phonon scattering and carrier concentration,it is hard to simultaneously realize the regulations of electrical and thermal transport properties by one simple approach.Herein,we develop Cu and Ce co-doping strategy that can not only greatly reduce lattice thermal conductivity but also improve the electrical transport properties.In this strategy,the incorporated Cu and Ce atoms could induce high-density SnSe_(2) nanoprecipitation arrays on the surface of SnSe microplate,and produce dopant atom point defects and dislocations in its interior,which form multi-scale phonon scattering synergy,thereby presenting an ultralow thermal conductivity of 0.275 W·m^(−1)·K^(−1) at 786 K.Meanwhile,density functional theory(DFT)calculations,carrier concentration,and mobility testing reveal that more extra hole carriers and lower conducting carrier scattering generate after Cu and Ce co-doping,thereby improving the electrical conductivity.The co-doped Sn_(0.98)Cu_(0.01)Ce_(0.01)Se bulk exhibits an excellent ZT value up to~1.2 at 786 K and a high average ZT value of 0.67 from 300 to 786 K.This work provides a simple and convenient strategy of enhancing the TE performance of polycrystalline SnSe.
基金This work was supported by the Guangxi Natural Science Foundation of China(Grant Nos.2020GXNSFAA159111,AD20159006,2020GXNSFAA159107,AD19245160,AD21220056,and AD19110020)the National Key R&D Program of China(Grant No.2017YFE0198000)the National Natural Science Foundation of China(Grant Nos.52061009,U21A2054,and 51961011).
文摘The argyrodite compounds(2 A(12)/B X6 m n n^(m+)+--(Am+=Li^(+),Cu^(+),and Ag^(+);Bn^(+)=Ga^(3+),Si^(4+),Ge^(4+),Sn^(4+),P^(5+),and As^(5+);and X^(2−)=S^(2−),Se^(2−),or Te^(2−)))have attracted great attention as excellent thermoelectric(TE)materials due to their extremely low lattice thermal conductivity(κl).Among them,Ag_(8)SnSe_(6)-based TE materials have high potential for TE applications.However,the pristine Ag_(8)SnSe_(6)materials have low carrier concentration(<1017 cm^(−3)),resulting in low power factors.In this study,a hydrothermal method was used to synthesize Ag_(8)SnSe_(6)with high purity,and the introduction of SnBr_(2)into the pristine Ag_(8)SnSe_(6)powders has been used to simultaneously increase the power factor and decrease the thermal conductivity(κ).On the one hand,a portion of the Br−ions acted as electrons to increase the carrier concentration,increasing the power factor to a value of~698 mW·m^(−1)·K^(−2)at 736 K.On the other hand,some of the dislocations and nanoprecipitates(SnBr_(2))were generated,resulting in a decrease ofκl(~0.13 W·m^(−1)·K^(−1))at 578 K.As a result,the zT value reaches~1.42 at 735 K for the sample Ag8Sn1.03Se5.94Br0.06,nearly 30%enhancement in contrast with that of the pristine sample(~1.09).The strategy of synergistic manipulation of carrier concentration and microstructure by introducing halogen compounds could be applied to the argyrodite compounds to improve the TE properties.
