Перегляд за Автор "Shelest, T. N."
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Документ Percolation effects and self-organization processes in Bi₂(Te₁₋ₓSeₓ)₃ solid solutions(Easy Conferences Ltd, 2019) Rogacheva, E. I.; Shelest, T. N.; Martynova, E. V.; Doroshenko, A. N.; Nashchekina, O. N.Документ Percolation effects and self-organization processes in Bi₂(Te₁₋ₓSeₓ)₃ solid solutions(Науково-технологічний комплекс "Інститут монокристалів", 2019) Rogacheva, E. I.; Shelest, T. N.; Martynova, E. V.; Doroshenko, A. N.; Nashchekina, O. N.; Men'shov, Yu. V.The room-temperature dependences of microhardness H, electrical conductivity σ, the Seebeck coefficient S, and thermoelectric power factor P on composition of Bi₂(Te₁₋ₓSeₓ)₃ solid solutions were measured in the concentration range x = 0 - 0.07. In the intervals x = 0.0075 - 0.0175 and x = 0.025 - 0.035, an anomalous decrease in H and S and increase in σ with increasing x were observed. The first concentration-dependent anomaly was attributed to critical phenomena, accompanying a percolation-type phase transition. The percolation threshold xc and the radius of deformation spheres R₀ around Se impurity atoms were estimated. The second anomaly is assumed to be connected with a short-range ordering in the solid solution. The non-monotonic character of the dependences of H on the load on an indenter, whose behavior depended on the impurity concentration, was attributed to the interaction of the deformation fields created by dislocations and impurity atoms.Документ Percolation effects and self-organization processes in cold-pressed Bi2(Te1−xSex)3 solid solutions(Elsevier Ltd, 2021) Rogacheva, E. I.; Martynova, E. V.; Shelest, T. N.; Doroshenko, A. N.; Nashchekina, O. N.It was established that the dependences of thermoelectric and mechanical properties of cold-pressed Bi2(Te1−xSex)3 alloys on composition (x = 0–0.07) exhibit a non-monotonic behavior in certain concentration ranges: an anomalous decrease in the Seebeck coefficient, thermoelectric power factor, and microhardness, and increase in electrical conductivity with increasing x. We observed similar anomalies earlier for cast Bi2(Te1−xSex)3 alloys and explained them by percolation and self-organization phenomena. Thus, the existence of the anomalies does not depend on the method of sample preparation. However, in pressed samples as compared to cast ones conductivity type changes from p to n and thermoelectric power factor increases.