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.

Переглянути

Зараз показуємо 1 - 20 з 411

Capacitive transducers based ITO/polyimide/Al2O3 thin film structure
(Національний технічний університет "Харківський політехнічний інститут", 2020) Zaitseva, Liliia; Vodoriz, Olga; Zaitsev, Roman
It has been developed and approbated prototypes of thin-film capacitor transducers based on Al/ITO/polyimide/Al2O3 heterosystem for capacitive acoustic control in metal objects in the modes of simultaneous acoustic signal reception and generation by capacitive transducers and in certain modes of acoustic signal generating or receiving that can realize objects monitoring with sensitivity at the level of piezoelectric transducers. The developed prototype of thin film capacitive transducer for monitoring pipelines by longwave capacitive method allows increasing the maximum distance between the capacitive transducers up to 10 meters. At a substrate temperature of 300 oC and a specific power of the magnetron of 0.31 W/cm2 on Upilex polyimide films were obtained layers of capacitive transducers with a thickness of 0.2-concentration of charge carriers was 8,3·1020 cm-3 and mobility - 44 cm2/(V·s). It has been engineered the thin film capacitive transducers which by using the polyamide film with 15 microns thickness of and alumina film with 1 micron thickness allow to increase the sensitivity of such method in 7-8 times, and the additional use of thin crystalline Al2O3 films deposited on a substrate of polyimide, allows to increase the value of the dielectric constant of the layer of the capacitive transduser from 3-4 relative units to 8.5-11.5 relative units. Experimental studies of the crystal structure of the developed transducers by X - ray diffractometry and research of their dielectric properties were carried out. The device was tested and the possibility of its use was shown along with the generally accepted methods of defectoscopy. It is shown that using the magnetron sputtering technology, which provides high adhesion to polyimide substrate layers, made possible produce the capacitive transducers for objects with various shape. Proposed and patented: capacitor method for receiving acoustic signals in non-destructive control and transducer of ultrasonic acoustic wave’s excitation and receiving.
Charge carrier mobility in semiconductor solid solutions and percolation phenomena
(2017) Rogacheva, E. I.; Nashchekina, O. N.; Martynova, E. V.
The existence of a range of an anomalous growth in charge carrier mobility under the transition to heavy doping is established for Bi₂Te₃–Sb₂Te₃ solid solutions. This confirms our suggestion about the universal character of critical phenomena accompanying the transition from impurity discontinuum to impurity continuum. The experimental results are analyzed in terms of percolation theory taking into account alloy scattering and spatial correlations of impurity centers.
Concentration anomalies of properties in Pb₁₋ₓGeₓTe solid solutions
(1993) Rogacheva, E. I.; Sinelnik, N. A.; Nashchekina, O. N.
The investigation of electrical conductivity, coefficient of thermal electromotive force, Hall coefficient, microhardness and mobility in Pb₁₋ₓGeₓΤe (x = 0 : 0.1) alloys in the temperature range of 77-300 K was carried out. Anomalies were detected in isotherms of properties in the vicinity of x = 0.008. The anomalies were treated as a manifestation of concentration phase transitions occurring in solid solutions of any kind and associated with existence of critical concentration (percolation threshold) at which the uninterrupted chain of interactions between impurity atoms is formed.
Concentration anomaly of heat capacity in PbTe based solid solutions
(2002) Rogacheva, E. I.; Sinelnik, N. A.; Krivulkin, I. M.
The temperature dependences of the heat capacity in the Pb₁₋ₓMnₓTe and Pb₁₋ₓGeₓTe (x = 0-0.04) solid solutions based on PbTe were obtained in the temperature range of 100-670 K. Pronounced peaks were observed in the isotherms of the heat capacity in the vicinity of x ~ 0.01-0.015. The presence of the peaks is explained on the basis of the idea about the existence of concentration phase transitions of percolation type, which take place in any solid solution and are related to transformation of impurity discontinuum into impurity continuum.
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.
Contrast Enhancement of X-Ray Fluorescence Spectra Using a Secondary Two-Layer Radiator
(Scientific and Technological Corporation "Institute for Single Crystals", 2011) Mikhailov, I. F.; Baturin, A. A.; Mikhailov, A. I.; Borisova, S. S.
Теоретически рассчитаны и экспериментально измерены распределение фона рассеянного излучения и контрастность аналитических линий образца при возбуждении флуоресценции с помощью двухслойного вторичного излучателя. Верхний слой служит для возбуждения линий легких элементов и является адсорбером сплошного спектра, рассеянного нижним слоем. Получено выражение для расчета оптимальной толщины верхнего слоя, при которой достигается максимальная контрастность спектров. При оптимальной толщине покрытия экспериментально удается получить 34 кратное повышение контрастности в диапазоне длин волн 0,7 10A по сравнению с однородным излучателем.
Crystal growth in amorphous films of tantalum pentoxide
(2023) Bagmut, A. G.
Amorphous films are formed on substrates at room temperature in the process of pulsed laser sputtering of Ta target in an oxygen atmosphere. Electron beam irradiation causes their crystallization with the formation of Ta2O5 crystals with hexagonal lattice. Electron microscope investigation, including “in situ” and video recording methods, revealed the following crystallization modes in different regions of the same amorphous film of Ta2O5. 1. Island polymorphous crystallization. 2. Interjacent crystallization mode. 3. Layer polymorphous crystallization mode. The presence of three different crystallization modes is explained by the phenomenon of polyamorphism in amorphous films.
Crystal growth modes and crystallization kinetics of amorphous films according to transmission electron microscopy "in situ"
(Universidade de Aveiro, Portugal, 2019) Bagmut, A. G.; Bagmut, I. A.
Crystallization and natural aging of thin films produced by pulsed laser evaporation of rhenium
(Institute for Single Crystals, 2013) Bagmut, A. G.; Bagmut, I. A.; Muravev, T. K.; Slabokrug, D. V.
Rhenium thin-film laser condensates have been obtained by pulsed laser evaporation (PLE) and their structure has been investigated. During annealing and natural aging of films the structural transformations have been examined. As a result of pulsed laser evaporation of Re in vacuum and in the oxygen atmosphere at P(O₂) = 10⁻³ Torr on (001) KCl substrates at room temperature, the amorphous films have been formed. Amorphous films become crystalline after annealing. The natural aging in air provides the formation of ReO₃ crystals on the film surface. The formation of crystals took place non-uniformly. The ReO₃-poor and ReO₃-rich crystal zones are formed. The ReO₃ crystalline structure is destroyed during annealing in vacuum. The polycrystalline films consisting of ReO₂ and ReO₃ crystals have been grown as a result of PLE of Re in oxygen atmosphere under P(O₂) = 10⁻² Torr on substrates at room temperature.
Crystallization of Films, Deposited with Laser Sputtering
(Bar-Ilan University, 2015) Bagmut, A. G.; Bagmut, I. A.
Defects of non-stoichiometry and dynamic stability of SnTe crystal lattice
(1993) Rogacheva, E. I.; Sinelnik, N. A.; Nashchekina, O. N.; Popov, V. P.; Lobkovskaya, T. A.
The temperature dependencies of coefficient of linear expansion α in the range of 4.2-300 K were obtained for SnTe samples with various degrees of deviation from stoichiometry. For the sample of stoichiometric composition in the α vs. temperature curves the anomalies connected with ferroelectric phase transition were detected. It was found that within cubic phase existence region α isotherms have a minimum at 50.4 at.% Te. Maximum dynamic stability at indicated composition is believed to be associated with the formation of vacancy superstructure.
Dependence of electrical conductivity on Bi₂Se₃ thin film thickness
(Institute for Single Crystals, 2017) Menshikova, S. I.; Rogacheva, E. I.; Sipatov, A. Yu.; Fedorov, A. G.
Effect of film thickness d on electrical conductivity σ of n-Bi₂Se₃ thin films (d = 25-420 nm) prepared by thermal evaporation in vacuum onto glass substrates was investigated. It was established that the electrical conductivity increases with increasing of the thin films thickness. The observed effect is explained as a manifestation of the classical size effect connected with diffuse scattering of electrons at the thin film interfaces. The experimental σ(d) dependence is satisfactorily described using the Fuchs-Sondheimer theory for the film thickness d > 60 nm. The specularity parameter and value of electrons mean free path are determined based of the experimental data.
Dependences of thermoelectric properties on the thickness of thin films of indium doped lead telluride
(Institute of Thermoelectricity, 2014) Menshikova, S. I.; Rogacheva, E. I.; Sipatov, A. Yu.; Matychenko, P. V.; Dobrotvorskaya, M. V.
Dependences of thermoelectric properties (the Seebeck coefficient S, the electric conductivity σ, the Hall coefficient RH, the carrier mobilityμ and the thermoelectric power P = S²·σ) on the thickness d (d = 10 – 255 nm) of thin films prepared by vacuum evaporation of indiumdoped PbTe crystals and subsequent condensation on (111) BaF₂ substrates were obtained. With decreasing thickness of films to d ≈ 40 nm, there is n- to p-type inversion of conduction which is related to a change in thermodynamic equilibrium conditions and partial reevaporation of lead and/or indium atoms. Extremes were found on the thickness dependences of properties at d₁ ≈ 20 nm which is indicative of hole gas quantization. In the range of thicknesses with n-type conduction there is a smooth change in thermoelectric properties with thickness which testifies to manifestation of classical size effect and is sufficiently well described in the framework of the Fuchs-Sondheimer theory.
Deviation from Stoichiometry and Temperature Dependences of Thermoelectric Properties of Bi2Te3 Crystals and Thin Films
(Прикарпатський національний університет імені Василя Стефаника, 2019) Rogacheva, E. I.; Novak, K. V.; Budnik, A. V.; Men'shov, Yu. V.
Dynamics of oscillation processes in siphon U-tubes
(Харківський національний університет імені В. Н. Каразіна, 2015) Tkachenko, O. Y.; Kazachkov, A. R.; Lykah, V. A.; Minakova, K. A.; Syrkin, E. S.
The dynamics of oscillation processes in a siphon U-tube is studied for the system of connected vessels fi lled with homogeneous liquid. The equations and phase paths describing the motion of non-viscous liquid and fountain eff ects are given, oscillation frequencies are considered. Oscillations are nonlinear in general case, but they turn into linear by setting special parameters of the system. Phase portraits are obtained and their dependences on parameters of the system are analyzed for the linear and non-linear cases. It is shown that the behavior of the deep and shallow water in such a system could be discussed using analogy with the propagation of elastic waves in condensed matter. Some interesting analogies between a siphon U-tube and hydrodynamic, mechanical, electromagnetic phenomena, wave motion are also analyzed.
Effect of aging on thermoelectric properties of the Bi2Te3 polycrystals and thin films
(Науково-технологічний комплекс "Інститут монокристалів", 2021) Rogacheva, E. I.; Doroshenko, A. N.; Novak, K. V.; Sipatov, A. Yu.; Khramova, T. I.; Saenko, S. A.
The temperature dependences (77-300 K) of the thermoelectric (TE) properties (the Seebeck coefficient S, electrical conductivity σ, Hall coefficient RH, Hall charge mobility μH>, and TE power factor P) were studied for freshly prepared and for exposed to air at room temperature during 5 years p-Bi2Te3 (60.0 at.% Te) and n-Bi2Te3 (62.8 at.% Te) polycrystals and thin films grown from them by thermal evaporation in vacuum. It was found that after aging, in the p- and n-Bi2Te3 bulk crystals and in the n-type film obtained from the n-Bi2Te3 crystal, type of conductivity is reserved but the p-type film obtained from the p-Bi2Te3 crystal, change the type of conductivity from hole to electronic. The activation energies of possible defect states were determined using the RH(T) dependences. After aging, at the temperatures close to room temperature, the p values of n-Bi2Te3 and p-Bi2Te3 polycrystals decreases by ~ 20 %, but p values of the n-type film grown from n-Bi2Te3 crystal increases by 20-30 %. In the p-type film obtained from p-Bi2Te3 polycrystal, and having changed the type of conductivity after aging, the p values exceed the p values of a film obtained from n-Bi2Te3 polycrystal by ~ 35 % at 250 K and by 25 % at 300 K, remaining at these temperatures below the p values for n-Bi2Te3 polycrystal after aging by ~ 15 %.
Effect of Bi on Mechanical and Transport Properties of Antimony
(Прикарпатський національний університет імені Василя Стефаника, 2019) Rogacheva, E. I.; Doroshenko, A. N.; Khramova, T. I.; Men'shov, Yu. V.
Effect of cold pressing on the concentration dependences of thermoelectric properties of (Bi1-xSbx)2Te3 solid solutions (x = 0 – 0.07)
(FOP Mezina, 2018) Martynova, K. V.; Rogacheva, E. I.
Effect of Deviation from Stoichiometry on Thermal Conductivity of Bi2Se3 Polycrystals
(Institute of Thermoelectricity National Academy of Sciences of Ukraine, 2020) Menshikova, S. I.; Rogacheva, E. I.
The dependences of electronic and lattice thermal conductivity on the composition (59.9 - 60.0) at. % Se of Bi2Se3 polycrystals subjected to a long-term annealing at 650 K. A non-monotonic behavior of these concentration dependences, associated with a change in the phase composition and defect structure under the deviation from stoichiometry, was observed. The boundaries of the Bi2Se3 homogeneity region were estimated. The results of the present work confirm those obtained earlier in our study of the effect of deviation from stoichiometry (59.9 - 60.0 at.% Se) on the electrical conductivity, Hall coefficient, Seebeck coefficient and microhardness of Bi2Se3polycrystals after a similar preparation technology.
Effect of Deviation from Stoichiometry on Thermoelectric Properties of Bi₂Te₃ Polycrystals and Thin Films in the Temperature Range 77-300 K
(Сумський державний університет, 2019) Rogacheva, E. I.; Novak, K. V.; Doroshenko, A. N.; Nashchekina, O. N.; Budnik, A. V.
Bi₂Te₃ semiconductor compound and Bi₂Te₃-based solid solutions are presently among the best lowtemperature thermoelectric materials. One of the methods of controlling the conductivity type and properties of Bi₂Te₃ is changing the stoichiometry of this compound. Earlier, we have obtained the room-temperature dependences of mechanical and thermoelectric properties of Bi₂Te₃ polycrystals on the degree of deviation from stoichiometry. The goal of this work is to investigate the behavior of such dependences at other temperatures. Bismuth telluride polycrystals with compositions in the range of 59.6-67.5 at. % Te were obtained, and for all the crystals the Seebeck coefficient, the Hall coefficient, electrical conductivity and charge carrier mobility were measured in the temperature range 77-300 K. On the basis of the temperature dependences, the isotherms of kinetic coefficients were plotted. It was found that similar to the room-temperature isotherms, the isotherms at lower temperatures were non-monotonic: they exhibited inversion of the conductivity sign between 60.5 and 61.0 at. % Te and extrema near 60.0 and 63.0 at. % Te. The experimental data are interpreted taking into account changes in the band and defect structures of Bi₂Te₃ under varying stoichiometry. The obtained results make it possible to control thermoelectric properties of Bi₂Te₃ polycrystals in the temperature range 77-300 K by changing the degree of deviation from stoichiometry.