Thermoelectric (TE) materials convert heat energy directly into electricity, and introducing new materials with high conversion efficiency is a great challenge because of the rare combination of interdependent electri...
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Thermoelectric (TE) materials convert heat energy directly into electricity, and introducing new materials with high conversion efficiency is a great challenge because of the rare combination of interdependent electrical and thermal transport properties required to be present in a single material. The TE efficiency is defined by the figure of merit ZT =( S 2 σ ) T / κ , where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the total thermal conductivity, and T is the absolute temperature. A new p‐type thermoelectric material, CsAg 5 Te 3 , is presented that exhibits ultralow lattice thermal conductivity (ca. 0.18 Wm −1 K −1 ) and a high figure of merit of about 1.5 at 727 K. The lattice thermal conductivity is the lowest among state‐of‐the‐art thermoelectrics; it is attributed to a previously unrecognized phonon scattering mechanism that involves the concerted rattling of a group of Ag ions that strongly raises the Grüneisen parameters of the material.
In order to investigate the thermal behaviour of radiation induced point defects in nuclear graphite, ETU10 graphite was implanted with 350 keV C+ ion to doses of 1015 and 1016 cm-2. The point defects introduced by th...
In order to investigate the thermal behaviour of radiation induced point defects in nuclear graphite, ETU10 graphite was implanted with 350 keV C+ ion to doses of 1015 and 1016 cm-2. The point defects introduced by the implantation were characterized by Positron Annihilation Doppler Broadening (PADB) and their thermal behaviour was studied during 'in situ' annealing at Delft Variable Energy Positron beam (VEP). The annealing was performed for 5 minutes at temperatures ranging from 300 K (as implanted) to 1500 K in steps of 100 K. For both doses, an annealing stage at around 450 K is observed followed by a second stage around 700 K. For the high dose implantation vacancy complexes are found which are stable up to a temperature around 1400K.
Increasing demand for energy, energy security and the need to minimize the impact on the environment related to energy are the major drivers for the research and development of alternative energy technologies. Polymer...
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Increasing demand for energy, energy security and the need to minimize the impact on the environment related to energy are the major drivers for the research and development of alternative energy technologies. Polymer electrolyte membrane fuel cell (PEMFC) is a promising alternative technology. But some compositions (such as Nafion, IPA, etc)will be introduced into catalyst layer in PEMFC intended or unintended. Therefore there is a concern about that Pt catalyst is able to keep its activity with coexistence of these components in PEMFC. This research was carried out to investigate the influence of Nafion and isopropyl alcohol(IPA) on the activity of Pt disk and Pt/C nanoparticle electrodes. The results show that Nafion has no influence on the instinct ORR activity on Pt but will block the oxygen transport and slow down the ORR velocity. In contrast to Nafion, IPA significantly suppresses the ORR activity on Pt.
Size controllable Barium titanate nanoparticles were synthesized in microemulsion consisting of water, OP-10, hexanol and cyclohexane under atmospheric pressure and low temperature, with Ba(OH)2·8H2O and tetrabut...
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There have been some encouraging results of use of ozone in medicine. However, as ozone is usually in gas state, unstable, and strong oxidability, it is difficult to be stored and used commonly. It is the key matter i...
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The microstructures and mechanical properties of the ductile cast iron （DI） specimens obtained by lost foam casting （LFC） with and without vibration were investigated. The results indicate that the number of the g...
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The microstructures and mechanical properties of the ductile cast iron （DI） specimens obtained by lost foam casting （LFC） with and without vibration were investigated. The results indicate that the number of the graphite nodule increases from 175 mm 2 of the specimens produced by LFC without vibration to 334 mm^-2 of the specimens produced by LFC with vibration, and the thickness of the ferrite shell increases. Meanwhile, the amount of the carbides decreases in the specimens produced by LFC with vibration and the granule structure then forms. These are mainly attributed to the ＂crystal shower＂ caused by the vibration. In addition, the tensile strength and elongation of DI specimens produced by LFC with vibration are improved due to the dispersion-strengthening of refined carbide and Dearlite colonv, uniform distribution of the graphite nodule, and increase of the amount of dimples and tearing edges.
The YAG porous ceramics were prepared under different sintering atmosphere. The results show that the amount of sintering neck increases as holding time prolonging and sintering temperature increasing, which improves ...
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The powder metallurgy method were used to sintering Co-Cr-W cemented carbide in the vacuum conditions. In order to research the effects of sintering temperature on the mechanical properties of the alloys, experiments ...
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A new application of metal organic framework （MOF） as a pseudo-capacitive material for supercapacitors is investigated. To this end, a simple nickel-based MOF, formulated Ni3（btc）2.12H2O, is synthesized via a hydr...
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A new application of metal organic framework （MOF） as a pseudo-capacitive material for supercapacitors is investigated. To this end, a simple nickel-based MOF, formulated Ni3（btc）2.12H2O, is synthesized via a hydrothermal reaction. As an electro-active material, such nickel-based MOF exhibits superior pseudo- capacitive behavior in KOH aqueous electrolyte with a high specific capacitance of 726 F g-1. Also, it displays good electrochemical stability with 94.6% of the initial capacitance over consecutive 1000 cycles. In addition, a simple asymmetric supercapacitor with a high energy density of 16.5 Wh kg-1 is successfully built using the nickel-based MOF as positive electrode and commercial activated carbon as negative electrode in KOH electrolyte.
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