The goal of the present work is a detailed study of the thermoelectric property-composition dependences of polycrystalline Bi-Sb solid solutions in the range of 0 -15 at.%0 Sb. The Seebeck coefficient, electrical conductivity, Hall coefficient, and magnetoresistance were measured in the temperature range 77 -300 K. In the isotherms of these properties, distinct extrema were observed in the certain concentration ranges. The presence of the concentration anomalies is attributed to 1) the transition from the dilute impurity range to the impurity continuum and possible selforganization processes accompanying this transition; 2) the reconstruction of the energy band structure under increasing Sb concentration. It was established that the maximum values of the figure of merit Z reached in the semiconductor region for the studied polycrystals, practically correspond to the values of Z observed in single crystals in the direction perpendicular to a trigonal axis. The obtained results should be taken into account when developing new thermoelectric materials based on Bi-Sb solid solutions.
Bending and Gaussian moduli of a homogenious single-component lipid bilayer are calculated analytically using microscopic model of the lipid hydrocarbon chains. The approach allows for thermodynamic averaging over different chains conformations. Each chain is modeled as a flexible string with finite bending rigidity and an incompressible cross-section area. The interchain steric repulsion is accounted for self-consistently determined single-chain confining parabolic potential. The model provides a simple analytical expression for the membrane bending modulus, which falls within a range of experimental values. An observed dependence of the modulus on hydrocarbon chain length is also reproduced. Correspondence between our microscopic model and the membrane theory of elasticity is established.
The dependences of the microhardness, electrical conductivity, the Hall coefficient, charge carrier mobility, magnetoresistance, and the Seebeck coefficient on Sb concentration (0–2 at.%) for Bi‐Sb solid solutions were obtained in the temperature range 77–300 K. It was established that the concentration dependences of the properties exhibit a non‐monotonic behavior. The existence of the peculiarities in the concentration curves is attributed to critical phenomena accompanying the transition of percolation type from an impurity discontinuum to an impurity continuum in Bi–Sb solid solutions. It was shown that the behavior of the curves is similar for cast and pressed samples and is independent of the annealing time. The results obtained in this work represent another evidence for our proposition about the universal character of critical phenomena that occur in solid solutions under the transition to an impurity continuum.
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