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Engineering Thermoelectric Performance of α-GeTe by Ferroelectric Distortion 被引量:1
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作者 Yuting Fan Chenghao Xie +5 位作者 Jun Li Xiangyu Meng Jinchang Sun Jinsong Wu Xinfeng tang gangjian tan 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2024年第2期171-179,共9页
The rhombohedralα-GeTe can be approximated as a slightly distorted rock-salt structure along its[111]direction and possesses superb thermoelectric performance.However,the role of such a ferroelectric-like structural ... The rhombohedralα-GeTe can be approximated as a slightly distorted rock-salt structure along its[111]direction and possesses superb thermoelectric performance.However,the role of such a ferroelectric-like structural distortion on its transport properties remains unclear.Herein,we performed a systematic study on the crystal structure and electronic band structure evolutions of Ge_(1-x)Sn_(x)Te alloys where the degree of ferroelectric distortion is continuously tuned.It is revealed that the band gap is maximized while multiple valence bands are converged at x=0.6,where the ferroelectric distortion is the least but still works.Once undistorted,the band gap is considerably reduced,and the valence bands are largely separated again.Moreover,near the ferro-to-paraelectric phase transition Curie temperature,the lattice thermal conductivity reaches its minima because of significant lattice softening enabled by ferroelectric instability.We predict a peak ZT value of 2.6 at 673 K inα-GeTe by use of proper dopants which are powerful in suppressing the excess hole concentrations but meanwhile exert little influence on the ferroelectric distortion. 展开更多
关键词 electronic band structures ferroelectric distortion lattice softening THERMOELECTRIC α-GeTe
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Rational design and synthesis of Cr_(1-x)Te/Ag_(2)Te composites for solid-state thermoelectromagnetic cooling near room temperature
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作者 孙笑晨 谢承昊 +3 位作者 陈思汗 万京伟 谭刚健 唐新峰 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第5期580-586,共7页
Materials with both large magnetocaloric response and high thermoelectric performance are of vital importance for all-solid-state thermoelectromagnetic cooling.These two properties,however,hardly coexist in single pha... Materials with both large magnetocaloric response and high thermoelectric performance are of vital importance for all-solid-state thermoelectromagnetic cooling.These two properties,however,hardly coexist in single phase materials except previously reported hexagonal Cr_(1-x)Te half metal where a relatively high magnetic entropy change(-△S_(M))of~2.4 J·kg^(-1)·K^(-1)@5 T and a moderate thermoelectric figure of merit(ZT)of~1.2×10^(-2)@300 K are simultaneously recorded.Herein we aim to increase the thermoelectric performance of Cr_(1-x)Te by compositing with semiconducting Ag_(2)Te.It is discovered that the in-situ synthesis of Cr_(1-x)Te/Ag_(2)Te composites by reacting their constitute elements above melting temperatures is unsuccessful because of strong phase competition.Specifically,at elevated temperatures(T>800 K),Cr_(1-x)Te has a much lower deformation energy than Ag_(2)Te and tends to become more Cr-deficient by capturing Te from Ag_(2)Te.Therefore,Ag is insufficiently reacted and as a metal it deteriorates ZT.We then rationalize the synthesis of Cr_(1-x)Te/Ag_(2)Te composites by ex-situ mix of the pre-prepared Cr_(1-x)Te and Ag_(2)Te binary compounds followed by densification at a low sintering temperature of 573 K under a pressure of 3.5 GPa.We show that by compositing with 7 mol%Ag_(2)Te,the Seebeck coefficient of Cr_(1-x)Te is largely increased while the lattice thermal conductivity is considerably reduced,leading to 72%improvement of ZT.By comparison,-△S_(M)is only slightly reduced by 10%in the composite.Our work demonstrates the potential of Cr_(1-x)Te/Ag_(2)Te composites for thermoelectromagnetic cooling. 展开更多
关键词 thermoelectromagnetic cooling thermoelectric MAGNETOCALORIC composite chromium telluride
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Transformation of Undesired Li_(2)CO_(3)into Lithiophilic Layer Via Double Replacement Reaction for Garnet Electrolyte Engineering 被引量:1
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作者 Jiaxu Zhang Ruohan Yu +3 位作者 Jun Li Huiyu Zhai gangjian tan Xinfeng tang 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2022年第3期962-968,共7页
Garnet-type solid-state electrolytes(SSEs)are a remarkable Li-ion electrolyte for the realization of next-generation all-solid-state lithium batteries due to their excellent stability against Li metal as well as high ... Garnet-type solid-state electrolytes(SSEs)are a remarkable Li-ion electrolyte for the realization of next-generation all-solid-state lithium batteries due to their excellent stability against Li metal as well as high ionic conductivities at room temperature.However,garnet electrolytes always contain undesired and hardly removable Li_(2)CO_(3) contaminations that have persistently large resistance and unstable interface contact with Li metal.This is a critical bottleneck for the practical application of garnet electrolytes.Here,we design a novel strategy to completely root out Li_(2)CO_(3) both inside and on the surface of garnet.This is achieved by a so-called double replacement reaction between Li_(2)CO_(3) and SiO_(2) during one-step hot press process for garnet electrolyte densification.It leads to in-situ transformation of LixSiOy(LSO)mostly locating around the grain boundaries of garnet.Due to the higher ion conductivity and better electrochemistry stability of LSO than Li_(2)CO_(3),the modified garnet electrolyte shows much improved electrochemical performance.Moreover,the wettability between modified garnet electrolyte and lithium metals was significantly enhanced in the absence of surface Li_(2)CO_(3).As a proof of concept,an assembled Li symmetric cell with modified garnet electrolyte displays a high critical current density(CCD)of 0.7 mA cm^(-2)and a low interfacial impedance(5Ωcm^(2))at 25℃.These results indicate that the upcycling of Li_(2)CO_(3)is a promising strategy to well-address the degradation and interfacial issue associated with garnet electrolytes. 展开更多
关键词 double replacement reaction garnet electrolytes lithiophilic layer solid-state lithium batteries
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Achieving superior performance in thermoelectric Bi_(0.4)Sb_(1.6)Te_(3.72)by enhancing texture and inducing high-density line defects 被引量:3
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作者 Junhao Qiu Yonggao Yan +11 位作者 Hongyao Xie Tingting Luo Fanjie Xia Lei Yao Min Zhang Ting Zhu gangjian tan Xianli Su Jinsong Wu Ctirad Uher Hongyi Jiang Xinfeng tang 《Science China Materials》 SCIE EI CAS CSCD 2021年第6期1507-1520,共14页
Miniaturization of efficient thermoelectric(TE)devices has long been hindered by the weak mechanical strength and insufficient heat-to-electricity conversion efficiency of zone-melted(ZM)ingots.Here,we successfully pr... Miniaturization of efficient thermoelectric(TE)devices has long been hindered by the weak mechanical strength and insufficient heat-to-electricity conversion efficiency of zone-melted(ZM)ingots.Here,we successfully prepared a robust high-performance p-type Bi_(0.4)Sb_(1.6)Te_(3.72)bulk alloy by combining an ultrafast thermal explosion reaction with the spark plasma sintering(TER-SPS)process.It is observed that the introduced excess Te not only enhances the(00l)-oriented texture to ensure an outstanding power factor(PF)of 5 mW m^(−1)K^(−2),but also induces extremely high-density line defects of up to 10^(11)–10^(12)cm^(−2).Benefiting from such heavily dense line defects,the enhancement of the electronic thermal conductance from the increased electron mobility is fully compensated by the stronger phonon scattering,leading to an evident net reduction in total thermal conductivity.As a result,a superior ZT value of~1.4 at 350 K is achieved,which is 40%higher than that of commercial ZM ingots.Moreover,owing to the strengthening of grain refinement and highdensity line defects,the mechanical compressive stress reaches up to 94 MPa,which is 154%more than that of commercial single crystals.This research presents an effective strategy for the collaborative optimization of the texture,TE performance,and mechanical strength of Bi2Te3-based materials.As such,the present study contributes significantly to the future commercial development of miniature TE devices. 展开更多
关键词 THERMOELECTRIC Bi_(2)Te_(3) TEXTURE line defect micro device
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Ferroelectric engineering:Enhanced thermoelectric performance by local structural heterogeneity
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作者 Xiangyu Meng Shuo Chen +9 位作者 Haoyang Peng Hui Bai Shujun Zhang Xianli Su gangjian tan Gustaaf Van Tendeloo Zhigang Sun Qingjie Zhang Xinfeng tang Jinsong Wu 《Science China Materials》 SCIE EI CAS CSCD 2022年第6期1615-1622,共8页
Although traditional ferroelectric materials are usually dielectric and nonconductive,GeTe is a typical ferroelectric semiconductor,possessing both ferroelectric and semiconducting properties.GeTe is also a widely stu... Although traditional ferroelectric materials are usually dielectric and nonconductive,GeTe is a typical ferroelectric semiconductor,possessing both ferroelectric and semiconducting properties.GeTe is also a widely studied thermoelectric material,whose performance has been optimized by doping with various elements.However,the impact of the ferroelectric domains on the thermoelectric properties remains unclear due to the difficulty to directly observe the ferroelectric domains and their evolutions under actual working conditions where the material is exposed to high temperatures and electric currents.Herein,based on in-situ investigations of the ferroelectric domains and domain walls in both pure and Sb-doped GeTe crystals,we have been able to analyze the dynamic evolution of the ferroelectric domains and domain walls,exposed to an electric field and temperature.Local structural heterogeneities and nano-sized ferroelectric domains are generated due to the interplay of the Sb^(3+)dopant and the Ge-vacancies,leading to the increased number of charged domain walls and a much improved thermoelectric performance.This work reveals the fundamental mechanism of ferroelectric thermoelectrics and provides insights into the decoupling of previously interdependent properties such as thermo-power and electrical conductivity. 展开更多
关键词 charged domain walls bound charge local structural heterogeneity high-performance thermoelectric
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