Кафедра "Фізика"

Постійне посилання колекціїhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/7578

Офіційний сайт кафедри http://web.kpi.kharkov.ua/tef

Кафедра "Фізика" створена у 2016 році шляхом об'єднання кафедри "Загальна та експериментальна фізика" і кафедри "Теоретична та експериментальна фізика", заснованої в 1972 році. .

У 1885 р. для викладання в інституті курсу фізики на посаду ад’юнкт-професора був запрошений магістр фізики приват-доцент Харківського університету Олександр Костянтинович Погорілко. У різні роки на кафедрі працювали видатні вчені-фізики: Пільчиков Н. Д., Латишев Г. Д., Обреїмов І. В., Пінес Б. Я., Ландау Л. Д., Корсунський М. І., Веркин Б. І., Дмитренко І. М., Базакуца В. А., Кулик І. О., Янсон І. К., Басс Ф. Г. Гуревич Ю. Г., Косевич В. М., Кукушкін Л. С. та ін.

Кафедра входить до складу Навчально-наукового інституту комп'ютерного моделювання, прикладної фізики та математики Національного технічного університету "Харківський політехнічний інститут".

У складі науково-педагогічного колективу кафедри працюють: 2 доктора та 16 кандидатів фізико-математичних наук, 2 кандидата технічних наук, 1 кандидат педагогічних наук; 2 співробітника мають звання професора, 12 – доцента.

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Фільтри

2014 - 20199

Налаштування

ORCID: search.filters.orcid.https://orcid.org/0000-0001-7584-656XКлючові слова: search.filters.subject.solid solutions

Результати пошуку

Зараз показуємо 1 - 9 з 9
  • Ескіз
    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.
  • Ескіз
    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.
  • Ескіз
    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.
  • Ескіз
    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.
  • Ескіз
    Публікація
    Electronic phase transitions in thin films of Bi1-xSbx solid solutions
    (Grupo Pacifico, 2018) Rogacheva, E. I.; Doroshenko, A. N.; Nashchekina, O. N.
  • Ескіз
    Публікація
    Peculiarities of concentration dependences of thermal conductivity in (PbTe)₁₋ₓ (Bi₂Te₃)ₓ semiconductor solid solutions
    (Інститут термоелектрики НАН України, 2014) Rogacheva, E. I.; Vodorez, O. S.; Nashchekina, O. N.; Dresselhaus, M. S.
    For the semiconductor (PbTe)₁₋ₓ (Bi₂Te₃)ₓ solid solutions, the temperature (T = 250 – 670 K) and concentration (x = 0 – 0.07) dependences of the total λ and lattice λp thermal conductivities were obtained. It was established that the dependences λ(x), λp(x) and β(x) (where β is the exponent in the λp ~ T⁻ᵝ dependence) have a non-monotonic dependence on x in this range of x. While showing a general tendency to decrease with increasing x, the three variables λ, λp, and β exhibit maxima at x = 0.005, 0.015 and x = 0.03. The oscillatory character of these dependences is attributable to the changes in thermal transfer processes and the mechanisms of phonon scattering under transitions from the dilute to the concentrated and associated solid solutions, with the transitions due to spatial ordering processes. The effective cross-section σs for phonon scattering by impurity atoms was estimated on the basis of the experimental data and theoretical calculations in accordance with the Klemens theory. The mean σs value in the homogeneity region of PbTe (x = 0 – 0.05) found experimentally coincides with the theoretically calculated σs value. However, in the region of the dilute solid solutions (x < 0.005), the σs value considerably exceeds the mean σs value. Also long-term aging reduces λ by ~ 15%.
  • Ескіз
    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.
  • Ескіз
    Публікація
    Temperature and concentration dependences of specific heat of Bi₁₋ₓSbₓ solid solutions
    (Науково-технологічний комплекс "Інститут монокристалів", 2018) Rogacheva, E. I.; Doroshenko, A. N.; Nashchekina, O. N.
    For Bi₁₋ₓSbₓ solid solutions, the concentration (x = 0 - 0.12) and temperature (170-525 K) dependences of specific heat Cp were obtained. At all temperatures studied, three peaks of Cp were observed near x = 0.015, x = 0.037, and x = 0.07. The observed effects were attributed to critical phenomena accompanying the second-order phase transitions: percolation transition from dilute to concentrated solid solutions, the transition to a gapless state, and the semimetal-semiconductor transition, respectively. It was shown that the values of critical indexes (α = 0.11 ± 0.01) are the same not only for different peaks but also for different temperatures and correspond to the values theoretically calculated within the framework of scale-invariant theory for three-dimensional (3D) models.
  • Ескіз
    Документ
    Thermoelectric properties of cold pressed samples of semiconductor (Bi₁₋ₓSbₓ)₂Te₃ solid solutions
    (Науково-технологічний комплекс "Інститут монокристалів", 2018) Martynova, K. V.; Rogacheva, E. I.
    The composition dependences of thermoelectric (TE) properties of (Bi₁₋ₓSbₓ)₂Te₃ solid solutions (0 < x < 1) produced by cold pressing and subsequent annealing were investigated at room temperature. Samples were prepared from cast polycrystals, obtained by the cooling of melt down to room temperature in evacuated quartz ampoules and subsequent annealing. It was established that cast samples exhibited p-type conductivity in the entire composition range, and an increase in the Sb₂Te₃ content led to the growth of electrical conductivity and drop of the Seebeck coefficient. The change of the conductivity type from positive to negative in the composition range x = 0 - 0.6 took place after cold pressing and composition dependencies of the properties became more complex. The maximum figure of merit value (Zmax = (3.1±0.4)·10⁻³ K⁻¹) that was achieved in cold-pressed annealed samples at x = 0.8 was comparable to the values of Z for single crystals of undoped (Bi₁₋ₓSbₓ)₂Te₃ solid solutions and for polycrystalline samples produced by other methods. It follows from the data obtained that the proposed method of preparing the samples of (Bi₁₋ₓSbₓ)₂Te₃ solid solutions by cold pressing and subsequent annealing may appear to be useful in thermoelectric devices.