RE 3Cu 3Sb 4(RE=Nd, Sm, Tb, Dy, Ho) was synthesized by arc melting method and their crystal structures were characterized by powder X ray method. The compounds crystallize in cubic system, Y 3Au 3Sb 4 type, sp...RE 3Cu 3Sb 4(RE=Nd, Sm, Tb, Dy, Ho) was synthesized by arc melting method and their crystal structures were characterized by powder X ray method. The compounds crystallize in cubic system, Y 3Au 3Sb 4 type, space group I43d (No.220), Pearson code cI40. The unit cell parameters are: Nd 3Cu 3Sb 4: a =0 96749(1) nm, V =0 90561(3) nm 3; Sm 3Cu 3Sb 4: a =0 96145(1) nm, V =0 88875(3) nm 3; Tb 3Cu 3Sb 4: a =0 95362(1) nm, V =0 86721(3) nm 3; Dy 3Cu 3Sb 4: a =0 95088(1) nm, V =0 85975(3) nm 3; Ho 3Cu 3Sb 4: a =0 9488(2) nm, V =0 8541(5) nm 3; Z =4. The structures are characterized by covalent bonded Cu Sb tetrahedra which form three dimensional networks by sharing corners. The rare earth atoms are distributed in the cages. The formula with the charge balance can be written as RE 3+ 3Cu 1+ 3Sb 3- 4 which are metallic Zintl phases having the weak metallic conductivity. The bonds have typical transitional features. General atomic coordination environment rules are followed. The unit cell parameters show the lanthanide contraction.展开更多
Zintl phase compounds AM2Sb2 （A=Ca, Sr, Ba, Eu, Yb;M=Zn, Cd） is a new class of promising thermoelectrics owing to their intrinsic features in electronic and crystal structure, such as a small or even disappeared ban...Zintl phase compounds AM2Sb2 （A=Ca, Sr, Ba, Eu, Yb;M=Zn, Cd） is a new class of promising thermoelectrics owing to their intrinsic features in electronic and crystal structure, such as a small or even disappeared band-gap, large density-of-states at the Fermi level, covalently bonded network of M-Sb, as well as the layered stacking by cations A2＋and anionic slabs （M2Sb2）2-. In addi-tion, the rich solid-state chemistry of Zintl phase allows structural modification and chemical substitution to adjust the fundamental transport parameters （carrier concentration, mobility, effective mass, electronic and lattice thermal conductivity） for improving the thermoelectric performance. In the present review, the recent advances in synthesis and thermoelectric characterization of title com-pounds AM2Sb2 were presented, and the effects of alloying or substitution for sites A, M and Sb on the electrical and thermal trans-port were emphasized. The structural disorder yielded by the incorporation of multiple ions significantly increased the thermoelectric figure of merit mainly resulted from the reduction of thermal conductivity without disrupting the carrier transport region in substance. Therefore, alloying or substitution has been a feasible and common route utilized to enhance thermoelectric properties in these Zintl phase compounds, especially for YbZn0.4Cd1.6Sb2 （ZT700 K=1.26）, EuZn1.8Cd0.2Sb2 （ZT650 K=1.06）, and YbCd1.85Mn0.15Sb2 （ZT650 K=1.14）.展开更多
Polycrystalline samples of Zintl phase EuCd2-xMnxSb2 （0.05≤x≤0.6） with the CaAl2Si2-type crystal structure （space group P3ml） were synthesized via a solid-state reaction followed by suitable cooling, annealing a...Polycrystalline samples of Zintl phase EuCd2-xMnxSb2 （0.05≤x≤0.6） with the CaAl2Si2-type crystal structure （space group P3ml） were synthesized via a solid-state reaction followed by suitable cooling, annealing and spark plasma sintering （SPS） processes. In samples with x=0.0, 0.1, 0.2, 0.4 and 0.6, the electrical conductivity, Seebeck coefficient, and thermal conductivity were performed as a function of temperature from 300 to 650 K. It was found that chemical substitution of Mn failed to optimize the thermoelectric properties of p-type conductive EuCd2Sb2. It was because that the Mn substitution induced the minority carriers （electrons）, resulting in decreasing the electrical conductivity drastically despite the fact that it enlarged the Seebeck coefficient and reduced the thermal conductivity synchronously.展开更多
Benefiting from the unique"Phonon-Glass,Electron-Crystal"(PGEC)characteristic,Zintl phases have been considered as a kind of promising thermoelectric materials.For the typical AM2X2 compounds with the CaAl2S...Benefiting from the unique"Phonon-Glass,Electron-Crystal"(PGEC)characteristic,Zintl phases have been considered as a kind of promising thermoelectric materials.For the typical AM2X2 compounds with the CaAl2Si2-type structure,YbMg_(2)Bi2 has shown competitive thermoelectric performance recently.Nevertheless,the optimization of YbMg_(2)Bi2 compounds is primarily focused on the substitution on Yb or Mg site.Herein,the Bi site is substituted by isoelectric Sb and the effect on the thermoelectric transport behavior is investigated.The partial substitution reduces the carrier concentration and induces the lattice deformation caused by the different atomic radius and mass between Bi and Sb,further leading to the decreased power factor and thermal conductivity.Fortunately,the reduction extent of the thermal conductivity outperforms that of power factor.Finally,the Sb substitution successfully results in a better thermoelectric performance compared with that of the pristine YbMg_(2)Bi1.98.Especially,the calculated energy conversion efficiency(a)of YbMg_(2)Bi1.88Sb0.1 which also possesses a relatively high output power density reaches the maximum value of 9.8% when Th=873 K,and Tc=300 K,respectively.This work demonstrates that the idea of substitution on anionic site should be a new strategy to achieve better ZT values for AM2X2 compounds.展开更多
We investigated the transport properties of isoelectronic substitution of Yb by Ca for Zintl phase YbCd2Sb2 below 300 K.The p-type Yb1-xCaxCd2Sb2(0.2≤x≤0.8) samples were synthesized via a solid-state reaction follow...We investigated the transport properties of isoelectronic substitution of Yb by Ca for Zintl phase YbCd2Sb2 below 300 K.The p-type Yb1-xCaxCd2Sb2(0.2≤x≤0.8) samples were synthesized via a solid-state reaction followed by suitable cooling,annealing,grinding,and spark plasma sintering(SPS) densification processes.For samples with x=0.2,0.4,0.5,0.6,0.8,the electrical conductivity,Seebeck coefficient,thermal conductivity,heat capacity and Hall effect measurements were carried out in the temperature range from 1...展开更多
Zintl-phase compounds have great potential in thermoelectric applications owing to their“phonon glasselectron crystal”(PGEC)structures.In this paper,a new Zintlphase thermoelectric material Ba Ag Sb is reported.Ba d...Zintl-phase compounds have great potential in thermoelectric applications owing to their“phonon glasselectron crystal”(PGEC)structures.In this paper,a new Zintlphase thermoelectric material Ba Ag Sb is reported.Ba deficiency increased the carrier concentration,and then suppressed the intrinsic excitation.The peak ZT value of Ba_(0.98)Ag Sb reached~0.56 at 773 K.Moreover,Eu alloying at Ba site not only lowered the lattice thermal conductivity by inducing point-defect scattering,but also improved the electrical properties by increasing the carrier mobility.Finally,a peak ZT of~0.73 was achieved in Ba_(0.78)Eu_(0.2)Ag Sb.展开更多
1-2-2-type Zintl phase compound has aroused great interest for potential thermoelectric applications.However,YbMg_(2)Sb_(2) is seldom studied due to the very low electrical conductivity resulting from the large differ...1-2-2-type Zintl phase compound has aroused great interest for potential thermoelectric applications.However,YbMg_(2)Sb_(2) is seldom studied due to the very low electrical conductivity resulting from the large difference in the electronegativity between Mg and Sb.In this paper,we adjust the covalently bonded network of MgeSb by replacing part of the Mg with Zn which has the electronegativity closer to that of Sb.The decreased polarity in the anionic framework offers more free distance for electrons for the enhanced Hall mobility and electrical conductivity.Together with the increased point defect and the decreased lattice thermal conductivity by introduction of Zn,the maximum ZT value of ~0.8 at 773 K is achieved in YbMg_(0.9)Zn_(1.1)Sb_(2) which is~100% enhancement compared with that of YbMg_(2)Sb_(2).展开更多
The layered 122 Zintl compounds have become an intriguing class of thermoelectric materials due to the promising electronic transport properties and inherently low thermal conductivity,showing the typical characterist...The layered 122 Zintl compounds have become an intriguing class of thermoelectric materials due to the promising electronic transport properties and inherently low thermal conductivity,showing the typical characteristics of"phonon-glass electron-crystal".Owing to the unprecedented performance tunability,the thermoelectric properties of the layered-structure compounds are completive with some traditional thermoelectric materials.Point defects involving vacancy,aliovalent doping and equivalent alloying atoms have been introduced to further enhance the thermoelectric properties.This review emphasizes the effects of various point defects on the thermoelectric parameters,and provides perspective on the strategies for increasing the thermoelectric figure of merit zT,which are believed to be applicable for improving the thermoelectric properties of many other compounds.展开更多
Antimony-based Zintl compounds AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn),which enable a broad range of manipulation on electrical and thermal transport properties,are considered as an important class of thermoelectric ma...Antimony-based Zintl compounds AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn),which enable a broad range of manipulation on electrical and thermal transport properties,are considered as an important class of thermoelectric materials.Phonon and carrier transport engineering were realized in YbMg2Sb2 via equivalent and aliovalent substitution of Zn and Ag,respectively.The roomtemperature thermal conductivity reduces from 1.96 to 1.15 W m^-1 K^-1 for YbMg2-xZnxSb2 due to the mass and strain fluctuation through the formation of the absolute solid solution of YbMg2Sb2-YbZn2Sb2.Furthermore,the carrier concentration has been further optimized by Ag doping(from 0.42×10^19 to 7.72×10^19 cm^-3 at room temperature),and thus the electrical conductivity and the power factor are enhanced effectively.The integrated aspects make the dimensionless figure of merit(zT)reach 0.48 at 703 K,which is 60%higher than the pristine YbMgZnSb2 sample.展开更多
Recently,n-type Mg3Sb1.5Bi0.5-based thermoelectric materials have attracted considerable attention for their extraordinary thermoelectric performance.Ideally,thermoelectric generators should be made of the same materi...Recently,n-type Mg3Sb1.5Bi0.5-based thermoelectric materials have attracted considerable attention for their extraordinary thermoelectric performance.Ideally,thermoelectric generators should be made of the same material system to avoid thermal mismatch in the practical application.In this work,p-type Mg3Sb1.5Bi0.5 which has almost the same composition as the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01 was synthesized by ball milling and spark plasma sintering,and then Na was chosen as an acceptor dopant to optimize the carrier concentration and further improve the thermoelectric performance.Na0.0075Mg2.9925Sb1.5Bi0.5 sample gets the highest ZT of~0.5 at 773 K.While Na0.005Mg2.995Sb1.5Bi0.5 sample shows the highest average ZT of~0.29 in the temperature range of 300 e773 K and matched thermal expansion behavior with the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01,which is of great significance for practical applications.Taking the Joule and Thompson heat into account,a high theoretical conversion efficiency(η)of~9.5%was calculated for the thermoelectric module consists of the present p-type Na0.005Mg2.995Sb1.5Bi0.5 and the state-of-the-art n-type Mg3.2Sb1.5Bi0.49Te0.01Mn0.01 with the leg length of 2 mm,and cold and hot side temperature of 300 K and 773 K,respectively,which shows a good potential for the use of this class of materials in the midtemperature power generation applications.展开更多
文摘RE 3Cu 3Sb 4(RE=Nd, Sm, Tb, Dy, Ho) was synthesized by arc melting method and their crystal structures were characterized by powder X ray method. The compounds crystallize in cubic system, Y 3Au 3Sb 4 type, space group I43d (No.220), Pearson code cI40. The unit cell parameters are: Nd 3Cu 3Sb 4: a =0 96749(1) nm, V =0 90561(3) nm 3; Sm 3Cu 3Sb 4: a =0 96145(1) nm, V =0 88875(3) nm 3; Tb 3Cu 3Sb 4: a =0 95362(1) nm, V =0 86721(3) nm 3; Dy 3Cu 3Sb 4: a =0 95088(1) nm, V =0 85975(3) nm 3; Ho 3Cu 3Sb 4: a =0 9488(2) nm, V =0 8541(5) nm 3; Z =4. The structures are characterized by covalent bonded Cu Sb tetrahedra which form three dimensional networks by sharing corners. The rare earth atoms are distributed in the cages. The formula with the charge balance can be written as RE 3+ 3Cu 1+ 3Sb 3- 4 which are metallic Zintl phases having the weak metallic conductivity. The bonds have typical transitional features. General atomic coordination environment rules are followed. The unit cell parameters show the lanthanide contraction.
基金supported by National Basic Research Program of China(2007CB607503)National Natural Science Foundation of China(50821004,10979069)
文摘Zintl phase compounds AM2Sb2 （A=Ca, Sr, Ba, Eu, Yb;M=Zn, Cd） is a new class of promising thermoelectrics owing to their intrinsic features in electronic and crystal structure, such as a small or even disappeared band-gap, large density-of-states at the Fermi level, covalently bonded network of M-Sb, as well as the layered stacking by cations A2＋and anionic slabs （M2Sb2）2-. In addi-tion, the rich solid-state chemistry of Zintl phase allows structural modification and chemical substitution to adjust the fundamental transport parameters （carrier concentration, mobility, effective mass, electronic and lattice thermal conductivity） for improving the thermoelectric performance. In the present review, the recent advances in synthesis and thermoelectric characterization of title com-pounds AM2Sb2 were presented, and the effects of alloying or substitution for sites A, M and Sb on the electrical and thermal trans-port were emphasized. The structural disorder yielded by the incorporation of multiple ions significantly increased the thermoelectric figure of merit mainly resulted from the reduction of thermal conductivity without disrupting the carrier transport region in substance. Therefore, alloying or substitution has been a feasible and common route utilized to enhance thermoelectric properties in these Zintl phase compounds, especially for YbZn0.4Cd1.6Sb2 （ZT700 K=1.26）, EuZn1.8Cd0.2Sb2 （ZT650 K=1.06）, and YbCd1.85Mn0.15Sb2 （ZT650 K=1.14）.
基金Project supported by Young Eastern Scholar Project of Shanghai Municipal Education Commission(QD2015031)
文摘Polycrystalline samples of Zintl phase EuCd2-xMnxSb2 （0.05≤x≤0.6） with the CaAl2Si2-type crystal structure （space group P3ml） were synthesized via a solid-state reaction followed by suitable cooling, annealing and spark plasma sintering （SPS） processes. In samples with x=0.0, 0.1, 0.2, 0.4 and 0.6, the electrical conductivity, Seebeck coefficient, and thermal conductivity were performed as a function of temperature from 300 to 650 K. It was found that chemical substitution of Mn failed to optimize the thermoelectric properties of p-type conductive EuCd2Sb2. It was because that the Mn substitution induced the minority carriers （electrons）, resulting in decreasing the electrical conductivity drastically despite the fact that it enlarged the Seebeck coefficient and reduced the thermal conductivity synchronously.
基金supported financially by the National Natural Science Foundation of China(Nos.51771065 and 51871082)。
文摘Benefiting from the unique"Phonon-Glass,Electron-Crystal"(PGEC)characteristic,Zintl phases have been considered as a kind of promising thermoelectric materials.For the typical AM2X2 compounds with the CaAl2Si2-type structure,YbMg_(2)Bi2 has shown competitive thermoelectric performance recently.Nevertheless,the optimization of YbMg_(2)Bi2 compounds is primarily focused on the substitution on Yb or Mg site.Herein,the Bi site is substituted by isoelectric Sb and the effect on the thermoelectric transport behavior is investigated.The partial substitution reduces the carrier concentration and induces the lattice deformation caused by the different atomic radius and mass between Bi and Sb,further leading to the decreased power factor and thermal conductivity.Fortunately,the reduction extent of the thermal conductivity outperforms that of power factor.Finally,the Sb substitution successfully results in a better thermoelectric performance compared with that of the pristine YbMg_(2)Bi1.98.Especially,the calculated energy conversion efficiency(a)of YbMg_(2)Bi1.88Sb0.1 which also possesses a relatively high output power density reaches the maximum value of 9.8% when Th=873 K,and Tc=300 K,respectively.This work demonstrates that the idea of substitution on anionic site should be a new strategy to achieve better ZT values for AM2X2 compounds.
基金supported by the National Basic Research Program of China (2007CB607503)National Natural Science Foundation of China (50821004)the MPG-CAS Partner Group
文摘We investigated the transport properties of isoelectronic substitution of Yb by Ca for Zintl phase YbCd2Sb2 below 300 K.The p-type Yb1-xCaxCd2Sb2(0.2≤x≤0.8) samples were synthesized via a solid-state reaction followed by suitable cooling,annealing,grinding,and spark plasma sintering(SPS) densification processes.For samples with x=0.2,0.4,0.5,0.6,0.8,the electrical conductivity,Seebeck coefficient,thermal conductivity,heat capacity and Hall effect measurements were carried out in the temperature range from 1...
基金supported by the National Natural Science Foundation of China (51871081, 11674078, 51971081, and 52001339)the Cheung Kong Scholar Reward Program Young Scholar Program of China (Q2018239)+3 种基金the Natural Science Foundation of Guangdong Province of China (2018A0303130033)the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province (2020B1515020023)Shenzhen Science and Technology Innovation Plan (KQJSCX20180328165435202 and JCYJ20180307154619840)the National Key Research and Development Program of China (2017YFA0303600)
文摘Zintl-phase compounds have great potential in thermoelectric applications owing to their“phonon glasselectron crystal”(PGEC)structures.In this paper,a new Zintlphase thermoelectric material Ba Ag Sb is reported.Ba deficiency increased the carrier concentration,and then suppressed the intrinsic excitation.The peak ZT value of Ba_(0.98)Ag Sb reached~0.56 at 773 K.Moreover,Eu alloying at Ba site not only lowered the lattice thermal conductivity by inducing point-defect scattering,but also improved the electrical properties by increasing the carrier mobility.Finally,a peak ZT of~0.73 was achieved in Ba_(0.78)Eu_(0.2)Ag Sb.
基金funded by the National Natural Science Foundation of China(11674078,24401019,51871077,and 51871081)the National Nature Science Foundation of Guangdong Province of China(2018A0303130033)+3 种基金Shenzhen fundamental research projects(JCYJ20170811155832192,JCYJ20160608161000821)Shenzhen Science and Technology Innovation Plan(KQISCX20180328165435202,JQJSCX20180328165656256)Startup Foundation from ShenzhenStartup Foundation from Harbin Institute of Technology(Shenzhen).
文摘1-2-2-type Zintl phase compound has aroused great interest for potential thermoelectric applications.However,YbMg_(2)Sb_(2) is seldom studied due to the very low electrical conductivity resulting from the large difference in the electronegativity between Mg and Sb.In this paper,we adjust the covalently bonded network of MgeSb by replacing part of the Mg with Zn which has the electronegativity closer to that of Sb.The decreased polarity in the anionic framework offers more free distance for electrons for the enhanced Hall mobility and electrical conductivity.Together with the increased point defect and the decreased lattice thermal conductivity by introduction of Zn,the maximum ZT value of ~0.8 at 773 K is achieved in YbMg_(0.9)Zn_(1.1)Sb_(2) which is~100% enhancement compared with that of YbMg_(2)Sb_(2).
基金Supported by the National Key Research and Development Program of China(2018YFA0702100)the National Natural Science Foundation of China(21771123,51772186 and 51632005)the Program of Introducing Talents of Discipline to Universities(D16002)。
文摘The layered 122 Zintl compounds have become an intriguing class of thermoelectric materials due to the promising electronic transport properties and inherently low thermal conductivity,showing the typical characteristics of"phonon-glass electron-crystal".Owing to the unprecedented performance tunability,the thermoelectric properties of the layered-structure compounds are completive with some traditional thermoelectric materials.Point defects involving vacancy,aliovalent doping and equivalent alloying atoms have been introduced to further enhance the thermoelectric properties.This review emphasizes the effects of various point defects on the thermoelectric parameters,and provides perspective on the strategies for increasing the thermoelectric figure of merit zT,which are believed to be applicable for improving the thermoelectric properties of many other compounds.
基金supported by the National Key Research and Development Program of China (2018YFA0702100)the National Natural Science Foundation of China (21771123)+2 种基金the Programme of Introducing Talents of Discipline to Universities (D16002)the Science and Technology Commission of Shanghai Municipality (15DZ2260300)Key Laboratory of Optoelectronic Materials Chemistry and Physics, Chinese Academy of Sciences (2008DP173016)
文摘Antimony-based Zintl compounds AM2Sb2(A=Ca,Sr,Ba,Yb,Eu;M=Mg,Zn,Cd,Mn),which enable a broad range of manipulation on electrical and thermal transport properties,are considered as an important class of thermoelectric materials.Phonon and carrier transport engineering were realized in YbMg2Sb2 via equivalent and aliovalent substitution of Zn and Ag,respectively.The roomtemperature thermal conductivity reduces from 1.96 to 1.15 W m^-1 K^-1 for YbMg2-xZnxSb2 due to the mass and strain fluctuation through the formation of the absolute solid solution of YbMg2Sb2-YbZn2Sb2.Furthermore,the carrier concentration has been further optimized by Ag doping(from 0.42×10^19 to 7.72×10^19 cm^-3 at room temperature),and thus the electrical conductivity and the power factor are enhanced effectively.The integrated aspects make the dimensionless figure of merit(zT)reach 0.48 at 703 K,which is 60%higher than the pristine YbMgZnSb2 sample.
基金the National Natural Science Foundation of China(Nos.51771065 and 51871082).
文摘Recently,n-type Mg3Sb1.5Bi0.5-based thermoelectric materials have attracted considerable attention for their extraordinary thermoelectric performance.Ideally,thermoelectric generators should be made of the same material system to avoid thermal mismatch in the practical application.In this work,p-type Mg3Sb1.5Bi0.5 which has almost the same composition as the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01 was synthesized by ball milling and spark plasma sintering,and then Na was chosen as an acceptor dopant to optimize the carrier concentration and further improve the thermoelectric performance.Na0.0075Mg2.9925Sb1.5Bi0.5 sample gets the highest ZT of~0.5 at 773 K.While Na0.005Mg2.995Sb1.5Bi0.5 sample shows the highest average ZT of~0.29 in the temperature range of 300 e773 K and matched thermal expansion behavior with the state-of-the-art n-type Mg3.2Sb1.5Bi0.49-Te0.01Mn0.01,which is of great significance for practical applications.Taking the Joule and Thompson heat into account,a high theoretical conversion efficiency(η)of~9.5%was calculated for the thermoelectric module consists of the present p-type Na0.005Mg2.995Sb1.5Bi0.5 and the state-of-the-art n-type Mg3.2Sb1.5Bi0.49Te0.01Mn0.01 with the leg length of 2 mm,and cold and hot side temperature of 300 K and 773 K,respectively,which shows a good potential for the use of this class of materials in the midtemperature power generation applications.
