69 research outputs found
Thermotunnel refrigerator with vacuum/insulator tunnel barrier: A theoretical analysis
The authors use two insulator layers in thermotunnel refrigerator to modify
the shape of the tunneling barrier so that electrons with high kinetic energy
pass it with increased probability. Theoretical analysis show that the overall
tunneling current between the electrodes contains an increased number of high
kinetic energy electrons and a reduced number of low energy ones, leading to
high efficiency. The particular case of vacuum gap and solid insulator layer is
calculated using digital methods. Efficiency remains high in the wide range of
the emitter electric field. The cooling coefficient is found to be as high as
40%-50% in the wide range of the emitter electric field.Comment: 9 pages, 3 figure
Mass singularities in light quark correlators: the strange quark case
The correlators of light-quark currents contain mass-singularities of the
form log(m^2/Q^2). It has been known for quite some time that these mass-
logarithms can be absorbed into the vacuum expectation values of other
operators of appropriate dimension, provided that schemes without normal-
ordering are used. We discuss in detail this procedure for the case of the mass
logarithms m^4 log(m^2/Q^2), including also the mixing with the other
dimension-4 operators to two-loop order. As an application we present an
improved QCD sum rule determination of the strange-quark mass. We obtain m_s(1
GeV)=171 \pm 15 MeV.Comment: 19 pages, Latex + 5 figures as uuencoded PS files, MZ-TH/94-21,
UCT-TP 214/9
Solvothermal synthesis and thermoelectric properties of indium telluride nanostring-cluster hierarchical structures
A simple solvothermal approach has been developed to successfully synthesize n-type α-In2Te3 thermoelectric nanomaterials. The nanostring-cluster hierarchical structures were prepared using In(NO3)3 and Na2TeO3 as the reactants in a mixed solvent of ethylenediamine and ethylene glycol at 200°C for 24 h. A diffusion-limited reaction mechanism was proposed to explain the formation of the hierarchical structures. The Seebeck coefficient of the bulk pellet pressed by the obtained samples exhibits 43% enhancement over that of the corresponding thin film at room temperature. The electrical conductivity of the bulk pellet is one to four orders of magnitude higher than that of the corresponding thin film or p-type bulk sample. The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures
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