Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using 'double probe' arrangement. The results showed that during the response process the thermal emf was decreased...Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using 'double probe' arrangement. The results showed that during the response process the thermal emf was decreased exponentially with the time and in case of low oxygen level the Seebeck coefficient and thermal conductivity of solid electrolyte agreed well with those in literatures.展开更多
Flexible piezoresistive pressure sensors can offer convenient detection of mechanical deformations for wearable electronics.Previous studies of flexible piezoresistive pressure sensors focus on the sensitivity but the...Flexible piezoresistive pressure sensors can offer convenient detection of mechanical deformations for wearable electronics.Previous studies of flexible piezoresistive pressure sensors focus on the sensitivity but the low-cost and self-powered sensors remain a challenge due to the deviation of resistance signal acquisition caused by thermoelectric voltage.Here,piezoresistive pressure sensors with ultralow Seebeck coefficient of-0.72μV/K based on carbon nanotubes(CNTs)/polyethyleneimine(PEI)/melamine(CPM)sponge are reported.Due to the diminished Seebeck effect,the CPM sponge pressure sensors successfully reduce the deviation to 18.75%and can keep stable sensitivity and resistance change under a very low working voltage and change temperature environment.The stable properties of the sensors make them successful to work for real-time sensing in self-powered wearable electronics.展开更多
In the previous study of longitudinal spin Seebeck effect（LSSE）, the thermal gradient was often generated by inserting the sample between the cool bath and the hot bath. For practical use, this method is too cumbers...In the previous study of longitudinal spin Seebeck effect（LSSE）, the thermal gradient was often generated by inserting the sample between the cool bath and the hot bath. For practical use, this method is too cumbersome to be easily integrated into modern electrical circuits. Since the laser can be easily focused into a small region, it will be more convenient and friendly to the integrated circuit. In this paper, we systematically investigate the LSSE and spin Hall magnetoresistance（SMR） of the Pt/Y_3 Fe_5 O_（12） heterostructure under focused laser-heating. We find that the extremely large voltage of inverse spin Hall effect（VISHE） can be obtained by reducing the diameter of laser or increasing the number of light spots.Meanwhile, even under the illumination of the ultraviolet light which will excite the electron from the valence band to the conduction band in yttrium iron garnet（YIG）, the magnitude of SMR is nearly constant. It indicates that the spin transport behavior of the adjacent Pt is independent of the electron configuration of YIG. The laser-heating method to generate LSSE will be very promising for modern integrated electronic circuits and will promote the application of spin caloritronics in practice.展开更多
In this paper, for the tool wear problem of the cutting process, the study on improving tool life has been done through the analysis of the Seebeck effect in the efficient turning process. The generation principle of ...In this paper, for the tool wear problem of the cutting process, the study on improving tool life has been done through the analysis of the Seebeck effect in the efficient turning process. The generation principle of the self-excited electric current in the cutting process is studied, and also its effect on the life of the turning cutter is studied, so as to reveal the mechanism of the self-excited electric current accelerating the wear of cutting tools. The study results show that the self-excited electric current which is generated during the cutting process is one of the main reasons that cause both the accelerated hardening and the low life of cutting tools to happen. Thus, if the generation of self-excited current is avoided and reduced, the cutting performance of cutting tools can be effectively improved, so to improve the tool life. The study can provide the anti-friction and anti-wear theory basis for the design of the efficient cutting tools.展开更多
Efficient generation of spin polarization is very important for spintronics and quantum computation. In chiral materials without magnetic order nor spin-orbit coupling, we find a new spin selectivity effect—chiral ph...Efficient generation of spin polarization is very important for spintronics and quantum computation. In chiral materials without magnetic order nor spin-orbit coupling, we find a new spin selectivity effect—chiral phonon activated spin Seebeck(CPASS)effect. Starting with the nonequilibrium distribution of chiral phonons under a temperature gradient, the CPASS coefficients are computed based on the Boltzmann transport theory. With both the phonon-drag and band transport contributions, the spin accumulations generated by the CPASS effect exhibit quadratic dependence on the temperature gradient. The strength of the CPASS effect and the relative magnitude of both contributions are tunable by the chemical potential modulation. The CPASS effect, which gives a promising explanation on the traditional chiral-induced spin selectivity effect, provides opportunities for the exploration of advanced spintronic devices based on chiral materials even in the absence of any magnetic order and spin-orbit coupling.展开更多
How magnetism affects the Seebeck effect is an important issue of wide concern in the thermoelectric community but remains elusive.Based on a thermodynamic analysis of spin degrees of freedom on varied d-electron-base...How magnetism affects the Seebeck effect is an important issue of wide concern in the thermoelectric community but remains elusive.Based on a thermodynamic analysis of spin degrees of freedom on varied d-electron-based ferromagnets and antiferromagnets,we demonstrate that in itinerant or partially itinerant magnetic compounds there exists a generic spin contribution to the Seebeck effect over an extended temperature range from slightly below to well above the magnetic transition temperature.This contribution is interpreted as resulting from transport spin entropy of(partially)delocalized conducting d electrons with strong thermal spin fluctuations,even semiquantitatively in a single-band case,in addition to the conventional diffusion part arising from their kinetic degrees of freedom.As a highly generic effect,the spin-dependent Seebeck effect might pave a feasible way toward efficient“magnetic thermoelectrics.”展开更多
Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations.Alternative routes based on the Thomson and Nernst effects o...Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations.Alternative routes based on the Thomson and Nernst effects offer new possibilities.Here,we present a comprehensive investigation of the thermoelectric properties of 1T-TiSe_(2),focusing on these effects around the charge density wave transition(≈200 K).The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450μVK^(-1) at 184 K,surpassing the Seebeck coefficient.Furthermore,1T-TiSe_(2) exhibits a remarkably broad temperature range(170-400 K)with a Thomson coefficient exceeding 190μV K^(-1),a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges.Additionally,the Nernst coefficient exhibits an unusual temperature dependence,increasing with temperature in the normal phase,which we attribute to bipolar conduction effects.The combination of solid-solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.展开更多
Thermoelectric properties of a topological insulator,monolayer HfC,are calculated using first-principles calculation,which accounts for the two contributions from edge and bulk states.By applying strain up to 8%along ...Thermoelectric properties of a topological insulator,monolayer HfC,are calculated using first-principles calculation,which accounts for the two contributions from edge and bulk states.By applying strain up to 8%along the a axis,the monolayer HfC shows the topological phase while it is in a non-topological state without strain.The figure of merit,ZT,for the topological phase becomes two-ordered magnitude larger(ZT∼2)because of larger electric conductivity than that of the non-topological phase due to edge current.The total Seebeck coefficient S,and ZT have maximum values when the chemical potential is located at the highest energy of the edge state.The peak of ZT comes from the fact that the product of divergent S and quickly-decreasing electric conductivity above the highest energy of the edge state.We further optimize S and ZT by changing the sample size and temperature.展开更多
Aluminum-induced crystallized silicon films were prepared on glass substrates by magnetron sputtering. Aluminum was added in the silicon films intermittently by the regular pulse sputtering of an aluminum target. The ...Aluminum-induced crystallized silicon films were prepared on glass substrates by magnetron sputtering. Aluminum was added in the silicon films intermittently by the regular pulse sputtering of an aluminum target. The amount of aluminum in the silicon films can be controlled by regulating the aluminum sputtering power and the sputtering time of the undoped silicon layer; thus, the Seebeck coefficient and electrical resistivity of the polyerystaUine silicon films can be adjusted. It is found that, when the sputtering power ratio of aluminum to silicon is 16%, both the Seebeck coefficient and the electrical resistivity decrease with the increasing amount of aluminum as expected; the Seebeck coefficient and the electrical resistivity at room temperature are 0.185-0.285 mV/K and 0.30-2.4 Ω.cm, respectively. By reducing the sputtering power ratio to 7%, however, the Seebeck coefficient does not change much, though the electrical resistivity still decreases with the amount of aluminum increasing; the Seebeck coefficient and electrical resistivity at room temperature are 0.219-0.263 mV/K and 0.26-0.80 Ω·cm, respectively.展开更多
The ZnO-Al films were prepared by R.F. magnetron sputtering system using a Zn-Al target (with purity of (99.99%).) The obtained films were characterized by X-ray diffraction, SEM and optical and electrical measurement...The ZnO-Al films were prepared by R.F. magnetron sputtering system using a Zn-Al target (with purity of (99.99%).) The obtained films were characterized by X-ray diffraction, SEM and optical and electrical measurements. The experimental results show that the properties of ZnO films can be further improved by annealing treatment. The crystallinity of ZnO films becomes better, and the optical gap energy is decreased, but thermoelectric power is enhanced after heat treatment. The optical gap energy decreases from 3.75 eV to 3.68 eV when the annealing temperature increases from 25 ℃ to 400 ℃.This can be ascribed to the decrease of carrier concentration, resulting in Burstein shift.展开更多
文摘Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using 'double probe' arrangement. The results showed that during the response process the thermal emf was decreased exponentially with the time and in case of low oxygen level the Seebeck coefficient and thermal conductivity of solid electrolyte agreed well with those in literatures.
基金Fundamental Research Fund for the Central Universities,China(Nos.2232020G-01 and 19D110106)Young Elite Scientists Sponsorship Program by China Association for Science and Technology,China(No.2017QNRC001)Graduate Student Innovation Fund of Donghua University,China(No.20D310111)。
文摘Flexible piezoresistive pressure sensors can offer convenient detection of mechanical deformations for wearable electronics.Previous studies of flexible piezoresistive pressure sensors focus on the sensitivity but the low-cost and self-powered sensors remain a challenge due to the deviation of resistance signal acquisition caused by thermoelectric voltage.Here,piezoresistive pressure sensors with ultralow Seebeck coefficient of-0.72μV/K based on carbon nanotubes(CNTs)/polyethyleneimine(PEI)/melamine(CPM)sponge are reported.Due to the diminished Seebeck effect,the CPM sponge pressure sensors successfully reduce the deviation to 18.75%and can keep stable sensitivity and resistance change under a very low working voltage and change temperature environment.The stable properties of the sensors make them successful to work for real-time sensing in self-powered wearable electronics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604265,51471134,51572222,and 11704386)the Fundamental Research Funds for the Central Universities,China(Grant Nos.3102018zy044 and 3102017jc01001)
文摘In the previous study of longitudinal spin Seebeck effect（LSSE）, the thermal gradient was often generated by inserting the sample between the cool bath and the hot bath. For practical use, this method is too cumbersome to be easily integrated into modern electrical circuits. Since the laser can be easily focused into a small region, it will be more convenient and friendly to the integrated circuit. In this paper, we systematically investigate the LSSE and spin Hall magnetoresistance（SMR） of the Pt/Y_3 Fe_5 O_（12） heterostructure under focused laser-heating. We find that the extremely large voltage of inverse spin Hall effect（VISHE） can be obtained by reducing the diameter of laser or increasing the number of light spots.Meanwhile, even under the illumination of the ultraviolet light which will excite the electron from the valence band to the conduction band in yttrium iron garnet（YIG）, the magnitude of SMR is nearly constant. It indicates that the spin transport behavior of the adjacent Pt is independent of the electron configuration of YIG. The laser-heating method to generate LSSE will be very promising for modern integrated electronic circuits and will promote the application of spin caloritronics in practice.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 51075108,51205095)the Key Project of Chinese Ministry of Education(Grant No.209034)+1 种基金the Natural Science Foundation of Heilongjiang Province (Grant No. E200919)the Support Program for Key Youth (GrantNo. 1154G39)
文摘In this paper, for the tool wear problem of the cutting process, the study on improving tool life has been done through the analysis of the Seebeck effect in the efficient turning process. The generation principle of the self-excited electric current in the cutting process is studied, and also its effect on the life of the turning cutter is studied, so as to reveal the mechanism of the self-excited electric current accelerating the wear of cutting tools. The study results show that the self-excited electric current which is generated during the cutting process is one of the main reasons that cause both the accelerated hardening and the low life of cutting tools to happen. Thus, if the generation of self-excited current is avoided and reduced, the cutting performance of cutting tools can be effectively improved, so to improve the tool life. The study can provide the anti-friction and anti-wear theory basis for the design of the efficient cutting tools.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12374044, 11904173, 11890703, and 12275133)supported by the Jiangsu Specially-Appointed Professor Program+1 种基金supported by the National Key R&D Project from Ministry of Science and Technology of China (Grant No. 2022YFA1203100)the “Shuangchuang” Doctor Program of Jiangsu Province (Grant No.JSS-CBS20210341)。
文摘Efficient generation of spin polarization is very important for spintronics and quantum computation. In chiral materials without magnetic order nor spin-orbit coupling, we find a new spin selectivity effect—chiral phonon activated spin Seebeck(CPASS)effect. Starting with the nonequilibrium distribution of chiral phonons under a temperature gradient, the CPASS coefficients are computed based on the Boltzmann transport theory. With both the phonon-drag and band transport contributions, the spin accumulations generated by the CPASS effect exhibit quadratic dependence on the temperature gradient. The strength of the CPASS effect and the relative magnitude of both contributions are tunable by the chemical potential modulation. The CPASS effect, which gives a promising explanation on the traditional chiral-induced spin selectivity effect, provides opportunities for the exploration of advanced spintronic devices based on chiral materials even in the absence of any magnetic order and spin-orbit coupling.
基金This work was supported by the National Science Foundation of China(no.11974389,no.11774404,and no.52088101)the National Key R&D Program of China(no.2017YFA0303100)the Chinese Academy of Sciences through the Strategic Priority Research Program under grant no.XDB33000000.
文摘How magnetism affects the Seebeck effect is an important issue of wide concern in the thermoelectric community but remains elusive.Based on a thermodynamic analysis of spin degrees of freedom on varied d-electron-based ferromagnets and antiferromagnets,we demonstrate that in itinerant or partially itinerant magnetic compounds there exists a generic spin contribution to the Seebeck effect over an extended temperature range from slightly below to well above the magnetic transition temperature.This contribution is interpreted as resulting from transport spin entropy of(partially)delocalized conducting d electrons with strong thermal spin fluctuations,even semiquantitatively in a single-band case,in addition to the conventional diffusion part arising from their kinetic degrees of freedom.As a highly generic effect,the spin-dependent Seebeck effect might pave a feasible way toward efficient“magnetic thermoelectrics.”
基金S.A.and M.Z.acknowledge support by NSF,grant number 2230352S.S.D.acknowledges support from the UVA Research Innovation AwardK.S.D.and D.L.work on TMDs has been supported by National Science Foundation Grant No.221949.
文摘Thermoelectric coolers utilizing the Peltier effect have dominated the field of solid-state cooling but their efficiency is hindered by material limitations.Alternative routes based on the Thomson and Nernst effects offer new possibilities.Here,we present a comprehensive investigation of the thermoelectric properties of 1T-TiSe_(2),focusing on these effects around the charge density wave transition(≈200 K).The abrupt Fermi surface reconstruction associated with this transition leads to an exceptional peak in the Thomson coefficient of 450μVK^(-1) at 184 K,surpassing the Seebeck coefficient.Furthermore,1T-TiSe_(2) exhibits a remarkably broad temperature range(170-400 K)with a Thomson coefficient exceeding 190μV K^(-1),a characteristic highly desirable for the development of practical Thomson coolers with extended operational ranges.Additionally,the Nernst coefficient exhibits an unusual temperature dependence,increasing with temperature in the normal phase,which we attribute to bipolar conduction effects.The combination of solid-solid pure electronic phase transition to a semimetallic phase with bipolar transport is identified as responsible for the unusual Nernst trend and the unusually large Thomson coefficient over a broad temperature range.
基金supported by the National Natural Science Foundation of China(Grant No.52031014)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0460000)+4 种基金the National Key Research and Development Program of China(Grant No.2022YFA1203900)Baojuan Dong acknowledges the National Natural Science Foundation of China(Grant Nos.12004228 and U21A6004)Riichiro Saito acknowledges a JSPS KAKENHI(Grant No.JP22H00283)Nguyen Tuan Hung acknowledges financial support from the Frontier Research Institute for Interdisciplinary Sciences,Tohoku UniversityWeijiang Gong acknowledges financial support from the National Natural Science Foundation of China(Grant No.51702146)。
文摘Thermoelectric properties of a topological insulator,monolayer HfC,are calculated using first-principles calculation,which accounts for the two contributions from edge and bulk states.By applying strain up to 8%along the a axis,the monolayer HfC shows the topological phase while it is in a non-topological state without strain.The figure of merit,ZT,for the topological phase becomes two-ordered magnitude larger(ZT∼2)because of larger electric conductivity than that of the non-topological phase due to edge current.The total Seebeck coefficient S,and ZT have maximum values when the chemical potential is located at the highest energy of the edge state.The peak of ZT comes from the fact that the product of divergent S and quickly-decreasing electric conductivity above the highest energy of the edge state.We further optimize S and ZT by changing the sample size and temperature.
基金financially supported by the Ministry of Science and Technology of China under a Joint Research Program of China-Japan-Korea(No.2010DFA62170)the National Natural Science Foundation of China(No.51172123)
文摘Aluminum-induced crystallized silicon films were prepared on glass substrates by magnetron sputtering. Aluminum was added in the silicon films intermittently by the regular pulse sputtering of an aluminum target. The amount of aluminum in the silicon films can be controlled by regulating the aluminum sputtering power and the sputtering time of the undoped silicon layer; thus, the Seebeck coefficient and electrical resistivity of the polyerystaUine silicon films can be adjusted. It is found that, when the sputtering power ratio of aluminum to silicon is 16%, both the Seebeck coefficient and the electrical resistivity decrease with the increasing amount of aluminum as expected; the Seebeck coefficient and the electrical resistivity at room temperature are 0.185-0.285 mV/K and 0.30-2.4 Ω.cm, respectively. By reducing the sputtering power ratio to 7%, however, the Seebeck coefficient does not change much, though the electrical resistivity still decreases with the amount of aluminum increasing; the Seebeck coefficient and electrical resistivity at room temperature are 0.219-0.263 mV/K and 0.26-0.80 Ω·cm, respectively.
文摘The ZnO-Al films were prepared by R.F. magnetron sputtering system using a Zn-Al target (with purity of (99.99%).) The obtained films were characterized by X-ray diffraction, SEM and optical and electrical measurements. The experimental results show that the properties of ZnO films can be further improved by annealing treatment. The crystallinity of ZnO films becomes better, and the optical gap energy is decreased, but thermoelectric power is enhanced after heat treatment. The optical gap energy decreases from 3.75 eV to 3.68 eV when the annealing temperature increases from 25 ℃ to 400 ℃.This can be ascribed to the decrease of carrier concentration, resulting in Burstein shift.
