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We study the motion of a planar thermal wave, which is simultaneously a phase boundary in a thin cooled film, driven by the application of an electrical current and Joule heating. Based on theoretical modeling by Brener and Temkin...
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We study the motion of a planar thermal wave, which is simultaneously a phase boundary in a thin cooled film, driven by the application of an electrical current and Joule heating. Based on theoretical modeling by Brener and Temkin (1996) [1] we employ a phase field model that reproduces the analytical predictions for planar front propagation and interface stability. Three-dimensional simulations of the growth of a filament advancing from one electrode to the other demonstrate the applicability of the model towards more complex geometries and problems originating from the microstructure formation in phase change materials.
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Doped ZnO has practical applications in the industry for thermoelectric generation, owing to its stability at high temperatures. However, the efficiency of energy conversion is not sufficient. In this work, we have focused on an e...
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Doped ZnO has practical applications in the industry for thermoelectric generation, owing to its stability at high temperatures. However, the efficiency of energy conversion is not sufficient. In this work, we have focused on an experimental evidence of a first-principles prediction in ab-plane tensile strain and the effective mass behavior in ZnO ceramics. The results showed a systematic c-axis compression of the lattice up to cla= 1.6010 with increase in the Al additive concentration. It was found that this lattice compression induced an increase in effective mass (m*) from 0.27 to 0.30 m_0, leading to the enhancement in the Seebeck coefficient normalized by carrier concentration. Besides, both carrier concentration and Hall mobility increased with increase in Al additive concentration. It was concluded that in the ion-doped ZnO system, a high compression of cla ratio due to heavy doping could be a key to improving the power factor.
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Because of thermoelectric (TE) effects, a local electric current density appears at an interphase interface during directional solidification of a binary metallic eutectic alloy. Thus, when a magnetic field is applied, a Lorentz f...
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Because of thermoelectric (TE) effects, a local electric current density appears at an interphase interface during directional solidification of a binary metallic eutectic alloy. Thus, when a magnetic field is applied, a Lorentz force is created. As a result, a thermoelectric magnetic convection (TEMC) in the liquid near the liquid/solid interface will develop. At the same time, a thermoelectric magnetic force (TEMF) will produce on eutectic phases. In this work, first of all, the TEMC and the TEMF during directional solidification of Al-Si eutectic are numerically simulated. The results show that when an applied magnetic field is below 10T, the values of the TEMC and the TEMF increase as the magnetic field increases. Under a 10T magnetic field, the values of the TEMC and the TEMF are of the order of 10~(-6)m/s and 10~6N/m~3, respectively. Then, Al-Si alloys are solidified directionally under an axial strong magnetic field and the effect of the magnetic field on the morphology of Al-Si alloys is investigated. The experimental results reveal that the application of the magnetic field has changed the morphology of Al-Si alloys significantly. Indeed, the magnetic field has destroyed the coupled growth of Al-Si eutectic and induced the CET of the primary Si dendrite. This is attributed to the TEMC in the liquid and the TEMF acting on eutectic phases. Above experimental results imply that thermoelectric effects play an important role to affect the growth of Al-Si eutectic during directional solidification under the strong magnetic field. Present work may initiate a new method to modify the microstructure of Al-Si alloys via an application of the magnetic field during directional solidification.
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We have investigated the specific heat and transport properties of the new ferromagnetic compound Nd3Al with the hexagonal Ni_3Sn structure. At low temperatures well below the Curie temperature of 74 K, the temperature dependence ...
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We have investigated the specific heat and transport properties of the new ferromagnetic compound Nd3Al with the hexagonal Ni_3Sn structure. At low temperatures well below the Curie temperature of 74 K, the temperature dependence of specific heat and electrical resistivity are consistently explained by considering the influence of magnon excitation with an anisotropy gap of about 30 K. An unexpected enhancement of the specific heat coefficient, γ～42 mJ/(mol_K~2) is observed. In the ferromagnetically ordered state, the predominant contribution of the term proportional to the square of resistivity to the anomalous Hall resistivity is observed. Thermoelectric power changes its sign from negative to positive at around 60 K with increasing temperature.
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Ultrahigh-pore-density nanoporous films with a pore diameter less than 10 nm and a pore density exceeding 10~(16) pores/m~2 have been fabricated by the phase separation of an Al-Si system and the subsequent removal of Al cylinders...
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Ultrahigh-pore-density nanoporous films with a pore diameter less than 10 nm and a pore density exceeding 10~(16) pores/m~2 have been fabricated by the phase separation of an Al-Si system and the subsequent removal of Al cylinders, for use in the template
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We investigated thermoelectric properties for PrTi2Al_(20) and PrV _2Al_(20) below room temperature down to 0.13 K. A clear positive peak has been observed at 75K in the thermoelectric power S for PrTi2Al_(20). Also for PrV_2Al_(2...
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We investigated thermoelectric properties for PrTi2Al_(20) and PrV _2Al_(20) below room temperature down to 0.13 K. A clear positive peak has been observed at 75K in the thermoelectric power S for PrTi2Al_(20). Also for PrV_2Al_(20), the similar S peak has been detected at 40 K. These peaks arise from the Kondo effect in the magnetic excited levels of the 4f -electronic state under a cubic crystalline electric field (CEF). In addition, for PrTi2Al_(20), S takes a minimum with a negative sign at 10K owing to the CEF effect, and shows an additional tiny negative hump below 2K as a signature of quadrupole ordering. On the other hand, S for PrV _2Al_(20) manifests a large negative peak at 3K with the magnitude of 3 μV/K. This gives a large enhancement in absolute S divided by temperature T, jSj=T, approximately below 10K on cooling. jSj=T reaches 4 μV/K_2 at 0.2 K, which is larger than that in the zero-T limit for a heavy-electron compound CeRu_2Si_2. This observation strongly indicates that the heavy-electron state brought by the quadrupolar Kondo effect is realized in the non-Kramers Γ3 ground state of PrV_2Al_(20).
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At ambient temperature, Al-1%Si wire of 25 mu m diameter was bonded successfully onto the Au/Ni/Cu pad by ultrasonic wedge bonding technology. Physical process of the bond formation and the interface joining essence were investiga...
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At ambient temperature, Al-1%Si wire of 25 mu m diameter was bonded successfully onto the Au/Ni/Cu pad by ultrasonic wedge bonding technology. Physical process of the bond formation and the interface joining essence were investigated. It is found that the wire was softened by ultrasonic vibration, at the same time, pressure was loaded on the wire and plastic flow was generated in the bonding wire, which promoted the diffusion for Ni into Al. Ultrasonic vibration enhanced the interdiffusion that resulted from the inner defects such as dislocations, vacancies. voids and so on, which ascribed to short circuit diffusion. (c) 2006 Elsevier B.V. All rights reserved.
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Rational design of single-molecular junction for efficient thermoelectric properties is a key prerequisite for thermoelectric conversion and fundamental challenge because of the existence of restrictive relationship be-tween Seebe...
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Rational design of single-molecular junction for efficient thermoelectric properties is a key prerequisite for thermoelectric conversion and fundamental challenge because of the existence of restrictive relationship be-tween Seebeck coefficient and conductance. Inspired by the promising mechanism for promoting thermoelectric properties depended on spin-filter efficiency, magnetothermoelectric properties of aluminum porphyrin (Al-porphyrin) molecular junction have been investigated in contact with ferromagnetic graphene electrodes at different temperature. It is found that spin-resolved Seebeck coefficient is larger than charge-resolved Seebeck coefficient, leading to an excellent spin-resolved power factor about 0.3 pW/K-2 at 0.25 eV for Al-porphyrin molecular junction. Ferromagnetic leads effectively realize thermal spin-filtering effect (SFE), which is induced by spin-resolved quantum interference (SQI) between graphene electrode and central nonmagnetic Al-porphyrin molecule. These results indicate the prospects of Al-porphyrin molecular junction applications in spin-caloritronics.
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