The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical r...The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.展开更多
Defect engineering is a commonly methodology used to enhance the thermoelectric performance of thermoelectric PbTe by improving its electronic transport properties.At the nanoscale,defects can induce quantum tunneling...Defect engineering is a commonly methodology used to enhance the thermoelectric performance of thermoelectric PbTe by improving its electronic transport properties.At the nanoscale,defects can induce quantum tunneling effects that significantly impact the electrical properties of materials.To understand the specific mechanisms underlying the quantum transport properties of PbTe,we employ the non-equilibrium Green's function(NEGF)method to investigate the effects of intrinsic defects(point defects and grain boundaries)on the electronic transport properties of PbTe-based nanodevices from a quantum mechanical perspective.Our results show that the Pb vacancy(VPb)has the highest conduction.The conduction depends on the defect type,chemical potential and bias voltage.The presence of intrinsic point defects introduces impurity levels,facilitating the electron tunneling and leading to an increase in the transmission coefficient,thereby enhancing the electronic transport properties.For PbTe containing grain boundaries,these boundaries suppress the electronic transport properties.The Te occupied twin boundary(Te-TB)exerts a stronger inhibitory effect than the Pb occupied twin boundary(Pb-TB).Nevertheless,the combined effect between twin boundaries and point defects can enhance the electrical properties.Therefore,in order to obtain highly conductive of PbTe materials,a Te-rich synthesis environment should be used to promote the effective formation of Pb vacancy.Our work offers a comprehensive understanding of the impact of defects on electron scattering in thermoelectric materials.展开更多
The relatively lower performance of n-type legs has significantly hindered the application of PbTe ma-terials in medium-temperature thermoelectric(TE)power generation,underscoring the urgent need to enhance the TE per...The relatively lower performance of n-type legs has significantly hindered the application of PbTe ma-terials in medium-temperature thermoelectric(TE)power generation,underscoring the urgent need to enhance the TE performance of n-type PbTe.In this study,electron-phonon decoupling was achieved through the precise manipulation of a single copper-doping element in PbTe(i.e.,Pb_(1.005-x)Cu_(2 x+0.003)Te),enabling the concurrent optimization of phonon transport and electrical properties.High-content Cu dop-ing induced substantial lattice strain and abundant precipitates,which effectively scattered heat-carrying phonons and significantly reduced lattice thermal conductivity.Simultaneously,the retention of high mo-bility and the self-regulation of electron concentration improved electrical performance across a broad temperature range.As a result,an impressive average zT of 1.3 was achieved from 523 to 823 K in n-type Pb_(0.985)Cu_(0.043)Te.Building on this,a seven-pair TE module was fabricated,attaining an energy conversion efficiency of∼8%under a temperature difference of 420 K.This work provides fresh insights into strate-gies for enhancing the TE performance of n-type PbTe.展开更多
基金National Key Research and Development Program of China(No.2022YFC2904900)the National Natural Science Foundation of China(No.U1902221).
文摘The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.
基金financial support from the National Natural Science Foundation of China(No.12474016)the program of“Distinguished Expert of Taishan Scholar”(No.tstp20221124)+4 种基金the National Natural Science Foundation of China(Nos.52172212,12474017)the Shandong Provincial Science Foundation(ZR2021YQ03)the program for“Young Scientists of Taishan Scholars”(No.tsqn202306184)financial support from the National Natural Science Foundation of China(No.12464034)the Natural Science Foundation of Ningxia,China(No.2024AAC05070)。
文摘Defect engineering is a commonly methodology used to enhance the thermoelectric performance of thermoelectric PbTe by improving its electronic transport properties.At the nanoscale,defects can induce quantum tunneling effects that significantly impact the electrical properties of materials.To understand the specific mechanisms underlying the quantum transport properties of PbTe,we employ the non-equilibrium Green's function(NEGF)method to investigate the effects of intrinsic defects(point defects and grain boundaries)on the electronic transport properties of PbTe-based nanodevices from a quantum mechanical perspective.Our results show that the Pb vacancy(VPb)has the highest conduction.The conduction depends on the defect type,chemical potential and bias voltage.The presence of intrinsic point defects introduces impurity levels,facilitating the electron tunneling and leading to an increase in the transmission coefficient,thereby enhancing the electronic transport properties.For PbTe containing grain boundaries,these boundaries suppress the electronic transport properties.The Te occupied twin boundary(Te-TB)exerts a stronger inhibitory effect than the Pb occupied twin boundary(Pb-TB).Nevertheless,the combined effect between twin boundaries and point defects can enhance the electrical properties.Therefore,in order to obtain highly conductive of PbTe materials,a Te-rich synthesis environment should be used to promote the effective formation of Pb vacancy.Our work offers a comprehensive understanding of the impact of defects on electron scattering in thermoelectric materials.
基金support from the Regional Innovation Cooperation Project of the Sichuan Science and Technology Program(No.2024YFHZ0204)the National Key Research and Development Program of China(No.2022YFB3803900)the Innovation Research Program of Sichuan University(No.2020SCUNL112).
文摘The relatively lower performance of n-type legs has significantly hindered the application of PbTe ma-terials in medium-temperature thermoelectric(TE)power generation,underscoring the urgent need to enhance the TE performance of n-type PbTe.In this study,electron-phonon decoupling was achieved through the precise manipulation of a single copper-doping element in PbTe(i.e.,Pb_(1.005-x)Cu_(2 x+0.003)Te),enabling the concurrent optimization of phonon transport and electrical properties.High-content Cu dop-ing induced substantial lattice strain and abundant precipitates,which effectively scattered heat-carrying phonons and significantly reduced lattice thermal conductivity.Simultaneously,the retention of high mo-bility and the self-regulation of electron concentration improved electrical performance across a broad temperature range.As a result,an impressive average zT of 1.3 was achieved from 523 to 823 K in n-type Pb_(0.985)Cu_(0.043)Te.Building on this,a seven-pair TE module was fabricated,attaining an energy conversion efficiency of∼8%under a temperature difference of 420 K.This work provides fresh insights into strate-gies for enhancing the TE performance of n-type PbTe.
