Кафедри
Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
Переглянути
5 результатів
Результати пошуку
Публікація 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.Документ Microhardness of Sb₂Te₃ – Bi₂Te₃ Solid Solutions(2015) Martynova, K. V.; Rogacheva, E. I.Документ Thermoelectric and mechanical properties of (Bi₁₋ₓSbₓ )₂Te₃(x = 0÷0.07) semiconductor solid solutions(National Academy of Sciences of Ukraine, 2016) Rogacheva, E. I.; Martynova, K. V.; Bondarenko, A. S.The dependences of thermoelectric properties and microhardness on the composition of polycrystalline (Bi₁₋ₓSbₓ )₂Te₃ solid solutions in the concentration range x = 0÷0.07 at room temperature were investigated. A drastic growth of microhardness was discovered with a simultaneous reduction of the Hall coefficient, the Seebeck coefficient and electric conductivity with increase in antimony content x = 0.005 – 0.01, following which with further increase in x to x = 0.01 – 0.015, the type of the dependences was reversed. The observed effect is attributable to a high degree of crystal lattice disorder with the introduction of the first portions of impurity and to subsequent relaxation processes with formation of percolation channels in crystal impurity subsystem. With further increase in x, the Hall coefficient and the Seebeck coefficient practically do not change with composition, and the observed more complicated dependence of microhardness and electric conductivity on x is interpreted as a manifestation of short-range processes in a solid solution.Публікація 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 Plastic deformation instabilities in Bi crystals under microindentation(Науково-технологічний комплекс "Інститут монокристалів", 2005) Rogacheva, E. I.; Yakovleva, A. A.; Lyubchenko, S. G.The dependences of microhardness H on the load on indentor were obtained for bismuth single- and polycrystals. The general tendency to H decreasing with P increasing up to ~0.15 N is observed. After that the microhardness practically does not change. In the range of P = 0.05-0.15 N, in the H(P) dependences the oscillations are detected whose presence is e[plained by qualititative changes in plastic deformation micromechanisms and in the crystal defect structure under increasing indentor load.