Magnesium-based materials have been regarded as promising candidates for large-scale,high-efficiency thermoelectric applications,owing to their excellent dimensionless figure of merit,high abundance,and low cost.In th...Magnesium-based materials have been regarded as promising candidates for large-scale,high-efficiency thermoelectric applications,owing to their excellent dimensionless figure of merit,high abundance,and low cost.In this review,we comprehensively summarize the recent advances of Mg-based thermoelectrics,including Mg_(2)X(X=Si,Ge,Sn),Mg3(Sb,Bi)_(2),andα-MgAgSb,from both material and device level.Their electrical and thermal transport properties are first elucidated based on the crystallographic characteristics,band structures,and phonon dispersions.We then review the optimization strategies towards higher thermoelectric performance,as well as the device applications of Mg-based thermoelectric materials and the related engineering issues.By highlighting the challenges and possible solutions in the end,this review intends to offer perspectives on the future research work to further enhance the performance of Mg-based materials for practical applications.展开更多
In order to reduce the oxidizing and volatilizing caused by Mg element in the traditional methods for synthesizing Mg2Sil-xSnx （x=0.2, 0.4, 0.6, 0.8） solid solutions, microwave irradiation techniques were used in pr...In order to reduce the oxidizing and volatilizing caused by Mg element in the traditional methods for synthesizing Mg2Sil-xSnx （x=0.2, 0.4, 0.6, 0.8） solid solutions, microwave irradiation techniques were used in preparing them as thermoelectric materials. Structure and phase composition of the obtained materials were investigated by X-ray diffraction （XRD）. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 750 K. It is found that Mg2Si1-xSnx solid solutions are well formed with excessive content of 5% （molar fraction） Mg from the stoichiometric MgESil.xSnx under microwave irradiation. A maximum dimensionless figure of merit, ZT, of about 0.26 is obtained for Mg2Si1-xSnx solid solutions at about 500 K for x=0.6.展开更多
In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave r...In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave radiation techniques.Structure and phase composition of the materials were investigated by X-ray diffraction.The electrical conductivity,Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 700 K.It is found that high purity Mg2Si powders can be obtained with excessive content of 8% Mg from the stoichiometric Mg2Si at 853 K and 2.5 kW for 30 min.A maximum dimensionless figure of merit,ZT,of about 0.13 was obtained for Mg2Si at 600 K.展开更多
Room-temperature thermoelectric materials provide promising solutions for energy harvesting from the environment,and deliver a maintenance-free power supply for the internet-of-things(IoTs).The currently available Bi_...Room-temperature thermoelectric materials provide promising solutions for energy harvesting from the environment,and deliver a maintenance-free power supply for the internet-of-things(IoTs).The currently available Bi_(2)Te_(3) family discovered in the 1950s,still dominates industrial applications,however,it has serious disadvantages of brittleness and the resource shortage of tellurium(1×10^(-3) ppm in the earth's crust).The novel Mg_(3)Sb_(2) family has received increasing attention as a promising alternative for room-temperature thermoelectric materials.In this review,the development timeline and fabrication strategies of the Mg 3 Sb 2 family are depicted.Moreover,an insightful comparison between the crystal-linity and band structures of Mg_(3)Sb_(2) and Bi_(2)Te_(3) is drawn.An outlook is presented to discuss challenges and new paradigms in designing room-temperature thermoelectric materials.展开更多
Thermoelectric materials Mg2Si0.8Sn0.2 were sintered under three different conditions including no electricity sintering（NCS）, low electricity sintering（LCS）,and high electricity sintering（HCS）. Thermoelectric p...Thermoelectric materials Mg2Si0.8Sn0.2 were sintered under three different conditions including no electricity sintering（NCS）, low electricity sintering（LCS）,and high electricity sintering（HCS）. Thermoelectric performance and microstructure of three group samples were measured and compared. The results indicate that the application of electric current during the sintering process changes the microstructure and significantly increases the density of samples, and increases the electric conductivity and the power factor. The electric current activated/assisted sintering is an effective way to obtain thermoelectric materials with excellent performance.展开更多
P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relativ...P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.展开更多
Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous...Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.展开更多
Rare-earth elements（Re） Sc and Y doped Mg_2Si thermoelectric materials were made via a field-activated and pressure-assisted synthesis（FAPAS） method at 1023-1073 K,50 MPa for 15 min.The samples created using this ...Rare-earth elements（Re） Sc and Y doped Mg_2Si thermoelectric materials were made via a field-activated and pressure-assisted synthesis（FAPAS） method at 1023-1073 K,50 MPa for 15 min.The samples created using this method have uniform and compact structures.The average grain size was about 1.5-2μm,the micro-content of Re did not change the matrix morphology.The sample with 2500 ppm Sc obtained the best Seebeck coefficient absolute value,about 1.93 times of that belonging to non-doped Mg_2Si at about 408 K.The electric conductivity of the sample doped with 2000 ppm Y becomes 1.69 times of that of pure Mg_2Si at 468 K,while the former had a better comprehensive electrical performance.Their thermal conductivity was reduced to 70%and 84% of that of non-doped Mg_2Si.Thus,the figure of merit and ZT of these two samples were enhanced visibly,which were 3.3 and 2.4 times of the non-doped samples at 408 K and 468 K,respectively.The maximal ZT belonging to samples doped with 2500 ppm Sc went up to 0.42 at about 498 K,higher than 0.40 of sample doped with 2000 ppm Y at 528 K and 0.25 of non-doped Mg_2Si at 678 K,and the samples doped with Sc seemed to get the best thermoelectric performances at lower temperature.展开更多
基金financial support from the National Natural Science Foundation of China(Grant Nos.52125103,52071041,12104071,11874356,U21A2054)。
文摘Magnesium-based materials have been regarded as promising candidates for large-scale,high-efficiency thermoelectric applications,owing to their excellent dimensionless figure of merit,high abundance,and low cost.In this review,we comprehensively summarize the recent advances of Mg-based thermoelectrics,including Mg_(2)X(X=Si,Ge,Sn),Mg3(Sb,Bi)_(2),andα-MgAgSb,from both material and device level.Their electrical and thermal transport properties are first elucidated based on the crystallographic characteristics,band structures,and phonon dispersions.We then review the optimization strategies towards higher thermoelectric performance,as well as the device applications of Mg-based thermoelectric materials and the related engineering issues.By highlighting the challenges and possible solutions in the end,this review intends to offer perspectives on the future research work to further enhance the performance of Mg-based materials for practical applications.
基金Project(2009BB4228) supported by the Natural Science Foundation of Chongqing City,ChinaProject(CK2010Z09) supported by the Research Foundation of Chongqing University of Science and Technology,China
文摘In order to reduce the oxidizing and volatilizing caused by Mg element in the traditional methods for synthesizing Mg2Sil-xSnx （x=0.2, 0.4, 0.6, 0.8） solid solutions, microwave irradiation techniques were used in preparing them as thermoelectric materials. Structure and phase composition of the obtained materials were investigated by X-ray diffraction （XRD）. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 750 K. It is found that Mg2Si1-xSnx solid solutions are well formed with excessive content of 5% （molar fraction） Mg from the stoichiometric MgESil.xSnx under microwave irradiation. A maximum dimensionless figure of merit, ZT, of about 0.26 is obtained for Mg2Si1-xSnx solid solutions at about 500 K for x=0.6.
基金Project (2009BB4228) supported by the Natural Science Foundation Project of Chongqing Science and Technology Commission,ChinaProject (CK2010Z09) supported by the Research Foundation of Chongqing University of Science and Technology,China
文摘In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave radiation techniques.Structure and phase composition of the materials were investigated by X-ray diffraction.The electrical conductivity,Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 700 K.It is found that high purity Mg2Si powders can be obtained with excessive content of 8% Mg from the stoichiometric Mg2Si at 853 K and 2.5 kW for 30 min.A maximum dimensionless figure of merit,ZT,of about 0.13 was obtained for Mg2Si at 600 K.
基金This work was supported by the Natural Science Foundation of China(grant number 51872133)National Key Research and Development Program of China(grant number 2019YFA0704900,2018YFB0703600)the Tencent Foundation through the XPLORER PRIZE and Shenzhen DRC project(grant number[2018]1433).
文摘Room-temperature thermoelectric materials provide promising solutions for energy harvesting from the environment,and deliver a maintenance-free power supply for the internet-of-things(IoTs).The currently available Bi_(2)Te_(3) family discovered in the 1950s,still dominates industrial applications,however,it has serious disadvantages of brittleness and the resource shortage of tellurium(1×10^(-3) ppm in the earth's crust).The novel Mg_(3)Sb_(2) family has received increasing attention as a promising alternative for room-temperature thermoelectric materials.In this review,the development timeline and fabrication strategies of the Mg 3 Sb 2 family are depicted.Moreover,an insightful comparison between the crystal-linity and band structures of Mg_(3)Sb_(2) and Bi_(2)Te_(3) is drawn.An outlook is presented to discuss challenges and new paradigms in designing room-temperature thermoelectric materials.
基金financially supported by the National Natural Science Foundation of China (Nos. 50975190 and 51101111)Shanxi Province Science Foundation for Youths (No. 2011021022-3)+1 种基金Shanxi Scholarship Council of China (No. 2012-033)the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi
文摘Thermoelectric materials Mg2Si0.8Sn0.2 were sintered under three different conditions including no electricity sintering（NCS）, low electricity sintering（LCS）,and high electricity sintering（HCS）. Thermoelectric performance and microstructure of three group samples were measured and compared. The results indicate that the application of electric current during the sintering process changes the microstructure and significantly increases the density of samples, and increases the electric conductivity and the power factor. The electric current activated/assisted sintering is an effective way to obtain thermoelectric materials with excellent performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A2054,52273285,52061009,52262032)the National Key Research and Development Program of China(No.2022YFE0119100)the Guangxi Science and Technology Planning Project(Grant No.AD21220056).
文摘P-type Mg_(3)Sb_(2)-based Zintls have attracted considerable interest in the thermoelectric(TE)field due to their environmental friendliness and low cost.However,compared to their n-type counterparts,they show relatively low TE performance,limiting their application in TE devices.In this work,we simultaneously introduce Bi alloying at Sb sites and Ag doping at Mg sites into the Mg_(3)Sb_(2)to coopera-tively optimize the electrical and thermal properties for the first time,acquiring the highest ZT value of∼0.85 at 723 K and a high average ZT of 0.39 in the temperature range of 323-723 K in sample Mg_(2.94)Ag_(0.06)Sb_(1.9)Bi_(0.1).The first-principle calculations show that the codoping of Ag and Bi can shift the Fermi level into the valence band and narrow the band gap,resulting in the increased carrier concentration from 3.50×10^(17)cm^(-3)in the reference Mg 3 Sb 0.9 Bi 0.1 to∼7.88×10^(19)cm^(-3)in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.As a result,a remarkable power factor of∼778.9μW m^(-1)K^(-2)at 723 K is achieved in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.Meanwhile,a low lattice thermal conductivity of∼0.48 W m^(-1)K^(-1)at 723 K is also obtained with the help of phonon scattering at the distorted lattice,point defects,and nano-precipitates in sample Mg 2.94 Ag 0.06 Sb 0.9 Bi 0.1.The synergistic effect of using the multi-element co-doping/-alloying to optimize electrical properties in Mg_(3)Sb_(2)holds promise for further improving the TE performance of Zintl phase materials or even others.
基金This work was supported by National Natural Science Foundation of China(Nos.11834012,51620105014,91963207,91963122,51902237)National Key R&D Program of China(No.2018YFB0703603,2019YFA0704900,SQ2018YFE010905)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT 2020e004).EPMA experiments were performed at the Center for Materials Research and Testing of Wuhan University of Technology.The S/TEM work was performed at the Nanostructure Research Center(NRC),which is supported by the Fundamental Research Funds for the Central Universities(WUT:2019III012GX).
文摘Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.
基金supported by the National Natural Science Foundation of China(Nos.50671070,50975190)the SXSCC(No.200826)
文摘Rare-earth elements（Re） Sc and Y doped Mg_2Si thermoelectric materials were made via a field-activated and pressure-assisted synthesis（FAPAS） method at 1023-1073 K,50 MPa for 15 min.The samples created using this method have uniform and compact structures.The average grain size was about 1.5-2μm,the micro-content of Re did not change the matrix morphology.The sample with 2500 ppm Sc obtained the best Seebeck coefficient absolute value,about 1.93 times of that belonging to non-doped Mg_2Si at about 408 K.The electric conductivity of the sample doped with 2000 ppm Y becomes 1.69 times of that of pure Mg_2Si at 468 K,while the former had a better comprehensive electrical performance.Their thermal conductivity was reduced to 70%and 84% of that of non-doped Mg_2Si.Thus,the figure of merit and ZT of these two samples were enhanced visibly,which were 3.3 and 2.4 times of the non-doped samples at 408 K and 468 K,respectively.The maximal ZT belonging to samples doped with 2500 ppm Sc went up to 0.42 at about 498 K,higher than 0.40 of sample doped with 2000 ppm Y at 528 K and 0.25 of non-doped Mg_2Si at 678 K,and the samples doped with Sc seemed to get the best thermoelectric performances at lower temperature.
