Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation ...Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of vip species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.展开更多
The investigation of the structure and thermoelectric properties of nanostructured solid solutions (Bi, Sb)2Te3 p-type has been carried out. The samples were obtained by grinding of original compositions in a planetar...The investigation of the structure and thermoelectric properties of nanostructured solid solutions (Bi, Sb)2Te3 p-type has been carried out. The samples were obtained by grinding of original compositions in a planetary ball mill and by spark plasma sintering (SPS). Initial powder has an average particle size of 10 - 12 nm according to transmission electron microscopy, and the size of the coherent scattering region (CSR) obtained by X-ray line broadening. During sintering at Ts = 250°C - 400°C, the grain size and CSR increased, which was associated with the processes of recrystallization. The maximum of size distribution of CSR shifts to larger sizes when Ts increases so that no broadening of X-ray lines at Ts = 400°C can take place. At higher Ts, the emergence of new nanograins is observed. The formation of nanograins is conditioned by reducing of quantity of the intrinsic point defects produced in the grinding of the source materials. The study of the electrical conductivity and the Hall effect in a single crystal allows to estimate the mean free path of the holes-L in the single crystal Bi0.5Sb1.5Te3 which at room temperature is 2 - 5 nm (it is much smaller than the dimensions of CSR in the samples). The method for evaluation of L in polycrystalline samples is proposed. At room temperature, L is close to the mean free path in single crystals. Scattering parameter holes in SPS samples obtained from the temperature dependence of the Seebeck coefficient are within the measurement error equal to the parameter of the scattering of holes in a single crystal. The figure of merit ZT of SPS samples as a function of composition and sintering temperature has been investigated. Maximum ZT, equal to 1.05 at room temperature, is obtained for the composition Bi0.4Sb1.6Te3 at Ts = 500°C and a pressure of 50 MPa. The causes of an apparent increase in thermoelectric efficiency are discussed.展开更多
High-strength high-performance p-type(Bi,Sb)_(2)Te_(3)are of pivotal importance for near-room-temperature thermoelectric conversions,the reliable synthesis and fabrication has been viewed of imperative priority.It is ...High-strength high-performance p-type(Bi,Sb)_(2)Te_(3)are of pivotal importance for near-room-temperature thermoelectric conversions,the reliable synthesis and fabrication has been viewed of imperative priority.It is known that the energy-favorable formation of anti-site Sb_(Te)’and vacancy v_(Sb)'''acceptor defects from high-temperature syntheses results in additional charge carriers and scattering centers for electrical and phonon transport.However,how p-type(Bi,Sb)_(2)Te_(3)with minimal lattice defects function remains to be scrutinized.Herein,we present the synergistic enhancements of mechanical robustness and thermoelectric property in crystallographic-defect-suppressed pristine(Bi,Sb)_(2)TeBi_(2)Te_(3)through a simple mechanical alloying combined with spark-plasma-sintering(SPS)process.The Sb_(Te)’and v_(Sb)'''acceptor defects were efficiently restrained,contributing to markedly increased charge carrier mobilities.A slightly enlarged band gap of 0.24 eV underpinned enhanced thermoelectric performance for pristine Bi_(0.3)Sb_(1.7)Te_(3)over a wide temperature range,delivering high zT300 K of 1.16 and zT_(ave)of 1.21 over 300-473 K.Interestingly,the confined in-situ grain coarsening during SPS with uniform dispersive nanopores readily endowed an ultra-high compressive strength of 206 MPa,surpassing that of reported(Bi,Sb)_(2)Te_(3)so far.A 7-pair module(coupled with n-Bi_(2)Te_(3))was fabricated,demonstrating a competitiveΔT over 70 K at T_(hot)=300 K.Furthermore,a power-generation module coupled with n-Mg_(3)SbBi registered a cutting-edge thermoelectric conversion efficiency of 9.5%at a temperature gradient of 250 K.The strategy eliminates the need of complex processing nor extrinsic doping for pristine(Bi,Sb)_(2)Te_(3),demonstrating great potentials in thermoelectric power generation and cooling applications.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFB3803900 and 2018YFA0702100)the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’Large-Scale Scientific Facility(Grant No.U1932106)the Sichuan University Innovation Research Program of China(Grant No.2020SCUNL112)。
文摘Tetradymite-structured chalcogenides,such as Bi_(2)Te_(3) and Sb_(2)Te_(3),are quasi-two-dimensional(2D)layered compounds,which are significant thermoelectric materials applied near room temperature.The intercalation of vip species in van der Waals(vdW)gap implemented for tunning properties has attracted much attention in recent years.We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi_(0.3)Sb_(1.7)Te_(3)(BST)for further improving thermoelectrics.The vdW-related defects(including extrinsic interstitial and intrinsic defects)induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture,thereby yielding excellent electrical properties,which are reflected in the power factor PF~4.43 mW·m^(-1)·K^(-2).Furthermore,the intercalation of Ga produces multi-scale lattice imperfections such as point defects,Te precipitations,and nanopores,realizing the low lattice thermal conductivity in BST-Ga samples.Ultimately,a peak zT~1.1 at 373 K is achieved in the BST-1%Ga sample and greatly improved by~22%compared to the pristine BST.The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.
文摘The investigation of the structure and thermoelectric properties of nanostructured solid solutions (Bi, Sb)2Te3 p-type has been carried out. The samples were obtained by grinding of original compositions in a planetary ball mill and by spark plasma sintering (SPS). Initial powder has an average particle size of 10 - 12 nm according to transmission electron microscopy, and the size of the coherent scattering region (CSR) obtained by X-ray line broadening. During sintering at Ts = 250°C - 400°C, the grain size and CSR increased, which was associated with the processes of recrystallization. The maximum of size distribution of CSR shifts to larger sizes when Ts increases so that no broadening of X-ray lines at Ts = 400°C can take place. At higher Ts, the emergence of new nanograins is observed. The formation of nanograins is conditioned by reducing of quantity of the intrinsic point defects produced in the grinding of the source materials. The study of the electrical conductivity and the Hall effect in a single crystal allows to estimate the mean free path of the holes-L in the single crystal Bi0.5Sb1.5Te3 which at room temperature is 2 - 5 nm (it is much smaller than the dimensions of CSR in the samples). The method for evaluation of L in polycrystalline samples is proposed. At room temperature, L is close to the mean free path in single crystals. Scattering parameter holes in SPS samples obtained from the temperature dependence of the Seebeck coefficient are within the measurement error equal to the parameter of the scattering of holes in a single crystal. The figure of merit ZT of SPS samples as a function of composition and sintering temperature has been investigated. Maximum ZT, equal to 1.05 at room temperature, is obtained for the composition Bi0.4Sb1.6Te3 at Ts = 500°C and a pressure of 50 MPa. The causes of an apparent increase in thermoelectric efficiency are discussed.
基金funding support of National Key Research and Development Program of China(Grant No.2022YFB3803900)funding support from Hebei Provincial Department of Science and Technology(236Z4403G,246Z4401G)+3 种基金Research Innovation Team Project of Hebei University(150000321008)Science Research Project of Hebei Education Department(Grant No.JZX2024008)supported by the Research Platform of Material Genome and the Synergic Extreme Condition User Facility in Huairou,Beijing Chinaalso supported by the Engineering Research Center of Zero-carbon Energy Buildings and Measurement Techniques,Ministry of Education。
文摘High-strength high-performance p-type(Bi,Sb)_(2)Te_(3)are of pivotal importance for near-room-temperature thermoelectric conversions,the reliable synthesis and fabrication has been viewed of imperative priority.It is known that the energy-favorable formation of anti-site Sb_(Te)’and vacancy v_(Sb)'''acceptor defects from high-temperature syntheses results in additional charge carriers and scattering centers for electrical and phonon transport.However,how p-type(Bi,Sb)_(2)Te_(3)with minimal lattice defects function remains to be scrutinized.Herein,we present the synergistic enhancements of mechanical robustness and thermoelectric property in crystallographic-defect-suppressed pristine(Bi,Sb)_(2)TeBi_(2)Te_(3)through a simple mechanical alloying combined with spark-plasma-sintering(SPS)process.The Sb_(Te)’and v_(Sb)'''acceptor defects were efficiently restrained,contributing to markedly increased charge carrier mobilities.A slightly enlarged band gap of 0.24 eV underpinned enhanced thermoelectric performance for pristine Bi_(0.3)Sb_(1.7)Te_(3)over a wide temperature range,delivering high zT300 K of 1.16 and zT_(ave)of 1.21 over 300-473 K.Interestingly,the confined in-situ grain coarsening during SPS with uniform dispersive nanopores readily endowed an ultra-high compressive strength of 206 MPa,surpassing that of reported(Bi,Sb)_(2)Te_(3)so far.A 7-pair module(coupled with n-Bi_(2)Te_(3))was fabricated,demonstrating a competitiveΔT over 70 K at T_(hot)=300 K.Furthermore,a power-generation module coupled with n-Mg_(3)SbBi registered a cutting-edge thermoelectric conversion efficiency of 9.5%at a temperature gradient of 250 K.The strategy eliminates the need of complex processing nor extrinsic doping for pristine(Bi,Sb)_(2)Te_(3),demonstrating great potentials in thermoelectric power generation and cooling applications.
