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Публікація Percolation transition and physical properties of Bi1-xSbx solid solutions at low Bi concentration(Elsevier Ltd, 2020) Rogacheva, E. I.; Doroshenko, A. N.; Khramova, T. I.; Nashchekina, O. N.; Fedorov, A. G.; Mateychenko, P. V.The dependences of microhardness H, electrical conductivity σ, charge carrier mobility μH, the Seebeck coefficient S, and thermoelectric power factor P = S2σ on the composition of Bi1-xSbx solid solutions in the vicinity of pure Sb (x = 1.0–0.975) were obtained. In the range of x = 0.9925–0.9875, an anomalous decrease in H and S and increase in σ and μH with increasing Bi concentration were observed. For all the alloys, the dependences of H on the load on an indenter G were plotted. It was found that the H(G) dependences for samples with x smaller than ~ 0.99 and for samples with x exceeding 0.99, exhibit different behavior. The results obtained are interpreted on the basis of our assumption about the existence of a percolation-type phase transition from impurity discontinuum to impurity continuum that occurs in any solid solution.Публікація Percolation effects in semiconductor IV-VI based solid solutions and thermoelectric materials science(Scrivener Publishing LLC, 2019) Rogacheva, E. I.; Nashchekina, O. N.The chapter reviews the present status of our experimental studies aimed at con firming the existence of anomalies in the dependences of thermoelectric (TE) and other properties on composition in semiconductor IV-VI–based solid solutions in the region of small impurity concentration. For all studied solid solutions, we observed an anomalous behavior of the isotherms of electrical conductivity, phonon thermal conductivity, heat capacity, charge carrier mobility, microhardness, the Seebeck coefficient, and TE figure of merit in the vicinity of (0.5–1) at. % of impurity. We believe that the observed phenomenon is connected with the existence of percolation-type phase transitions corresponding to the transition from dilute solid solutions to the impurity continuum and is accompanied by self-organization processes. The non-monotonic behavior of the concentration dependences of the TE properties and the underlying percolation phenomena should be taken into consideration when developing efficient TE materials and optimizing their properties. To get additional confirmation of the assumption regarding the universal character of phase transitions connected with the formation of the impurity continuum, it is necessary to expand the range of objects to be studied as well as spectrum of properties to be measured.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.Публікація Temperature and magnetic field dependences of thermoelectric properties of Bi1-xSbx solid solutions in the range x = 0-0.25(Elsevier Ltd, 2021) Rogacheva, E. I.; Doroshenko, A. N.; Nashchekina, O. N.Bi1–xSbx solid solutions are the best n-type thermoelectric materials for use at temperatures ≤200 K. An important parameter determining material’s figure of merit is charge carrier concentration. To determine it correctly, one should carry out measurements in a weak magnetic field. On the basis of the magnetic field dependences of the Hall coefficient and magnetoresistance, the dependences of the weak magnetic field boundary Bc on composition (x = 0–0.25) and temperature (T = 77–300 K) for polycrystalline Bi1–xSbx alloys were plotted. It was established that the Bc(x) dependences exhibit a non-monotonic behavior which is attributed to the existence of electronic phase transitions.Публікація Concentration dependences of galvanomagnetic and thermoelectric properties of Bi1-xSbx thin films in the range x = 0 – 0.25(Національна академія наук України, 2019) Rogacheva, E. I.; Doroshenko, A. N.; Sipatov, A. Yu.; Nashchekina, O. N.Публікація 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.Публікація Temperature and magnetic field dependences of thermoelectric properties of Bi1-xSbx solid solutions in the range x = 0 – 0.25(Easy Conferences Ltd, 2019) Rogacheva, E. I.; Doroshenko, A. N.; Nashchekina, O. N.Публікація Size effects in transport properties of Bi1-xSbx thin films(Grupo Pacifico, 2018) Rogacheva, E. I.; Orlova, D. S.; Nashchekina, O. N.Публікація Electronic phase transitions in thin films of Bi1-xSbx solid solutions(Grupo Pacifico, 2018) Rogacheva, E. I.; Doroshenko, A. N.; Nashchekina, O. N.Публікація Influence of Composition on the Thermoelectric Properties of Bi1-xSbx Thin Films(IOP Publishing Ltd, 2016) Rogacheva, E. I.; Nashchekina, O. N.; Doroshenko, A. N.; Sipatov, A. Yu.; Dresselhaus, M. S.
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