The Department of Physics for Multiparametrical Structural Diagnostics was founded in 2016 by way of reorganization of the Department of Solid State Theory. Since foundation of the Department of Solid State Theory in 1950 and until 1987, Prof. A. A. Smirnov, Member of the Ukrainian SSR A.S., headed the department. Since1987 and till 2014, Prof. V. B. Molodkin, Corresponding Member of the N.A.S. of Ukraine, became its head. Prof.A. I. Nizkova headed the department in 2014–2015, and Prof., Dr.Sci (Phys.-Math.) V.A. Tatarenko was in charge of the department in 2015–2016.
A number of studies carried out in the department focuses on the theory of electrical resistance of metals and alloys having different-type defects of a crystal structure. Under the direction of A. A. Smirnov, M. O.Krivoglaz, Z. A.Matysina and A. I.Nosar constructed the theory of residual electrical resistance of ordering alloys within the scope of the many-electron metal model; the dependences of such a resistance on the long-range order parameters, correlation and values characterizing various alloy-lattice imperfections were determined. These results generalized the studies of A. A. Smirnov, which he had conducted in the Institute of Physics of Metals of the Ural Division of the A.S. of USSR before 1947 (Sverdlovsk—at present, Yekaterinburg).
The theory of rays’ scattering within the imperfect crystals as well as the theory of neutron-diffraction analysis of alloys, taking into account long-range order, correlation, geometrical distortions, and effects of magnetic scattering, was further developed in the department. Based on the latter, a neutron diffraction method was developed to investigate the defects of alloy structure. (V. M. Danylenko, M. O. Krivoglaz, D. R. Rizdvyanetskii, A. A. Smirnov).
M. O. Krivoglaz developed the method of fluctuation waves and, together with K. P. Ryaboshapka, he constructed the kinematical theories of X-ray scattering on static distortions and of critical scattering; they proposed a classification of defects, according to roentgenographic effects induced by imperfections, and investigated the scattering by dislocations.
V. B. Molodkin and O. O. Tikhonova developed the dynamical theory of X-ray and electron scatterings for crystals with imperfections of different types as well as the theory of direct methods to observe the crystal-structure defects.
In collaboration with A. A. Smirnov, M. O. Krivoglaz proposed a new method to study the Fermi-surface shapes for metals and alloys, which is based on studying the angular distribution of quanta formed by annihilation of positrons with conduction electrons in single-crystalline samples. Magnetic fields, low temperatures, and high material purity are not required for using this method. Thereby, it is favourably compared with many well-known methods and is successfully applied in experimental physics.
A lot of attention was given to the development of molecular-kinetic and thermodynamical theory of metals and alloys. A. A. Smirnov and M. O. Krivoglaz constructed the theory of diffusion in ordering alloys for the first time. They predicted a number of new effects related to the impact of atomic ordering on diffusion of atoms. These effects were discovered experimentally in Russia, USA, and Poland. The theory of decomposition of alloys containing impurity atoms on sites and in interstices of crystal lattice was advanced.
The method of bifurcation points of an equilibrium curve was developed. With using this method, it is possible to investigate the order–disorder and order–order phase transformations in alloys with several phase transitions and to predict the formed superstructure types (V. V.Heichenko, A. A.Smirnov).
The theory of atomic ordering under high pressures and the theory of interplay of two cooperative phenomena, namely, atomic and magnetic-moment orderings (in ferro- and antiferromagnetic materials), were developed. They allowed to reveal a number of effects: peculiarities of state diagrams related to the interplay of atomic ordering and magnetization in alloys, changes of both the temperature and the kind of phase transition, etc. (V. V.Heichenko, V. M.Danylenko, O. K.Kanyuka, D. R.Rizdvyanetskii, V. I. Ryzhkov, A. A.Smirnov).
Later, T. M. Radchenko and V. A.Tatarenko improved these theories of ordering; they took into account long-range interatomic interactions (manifesting themselves in all coordination shells) and broadened the theory for cases of substitutional–interstitial alloys (with magnetic constituents of arbitrary spin numbers).
The theory of isotopic ordering of hydrogen isotopes in interstices was developed and led to possibility of nonmonotonic temperature dependence of the order parameters, if vacant interstices are available (L. B. Kvashnina, A. A. Smirnov).
The composition and order-parameter distributions close to the surface of the finite crystal alloys were investigated (A. M. Bobyr, A. I. Grankina, V. I. Ryzhkov).
In cooperation with the GDR Academy of Sciences and other institutions, Yu. V. Kornyushin carried out extensive studies of transport phenomena in the miscellaneous external fields.
A. A. Smirnov with colleagues suggested the theory of diffusion and viscosity in simple liquids, which is not concerned with pseudocrystalline approximation. The next step was the derivation of the new-type temperature (A. A. Smirnov, D. R. Rizdvyanetskii) and pressure (A. A. Smirnov, V. A. Tatarenko) dependences of viscosity and self-diffusion coefficients corresponding to experimental data on liquid noble gases and liquid metals.
The theory of diffusion and thermal diffusion in the interstitial alloys at high concentrations of interstitial atoms in different-type interstices within the metal lattice as well as the theory of phase transformations with the order change in the system of interstitial atoms in non-equivalent interstices within the lattice have been developed (A. A. Smirnov).
For the first time, A. A.Smirnov developed the self-consistent molecular-kinetic theory of subtraction alloys, which explained main experimentally observed peculiarities of structural and thermodynamical characteristics of such alloys.
His disciples, for the first time, carried out the geometrically-complete symmetry–configuration and statistical-thermodynamic analyses; on this basis, all possible types of thermodynamically stable (against antiphase shifts) f.c.c.- and h.c.p.-lattice-based interstitial superstructures (V. M.Bugaev, V. A. Tatarenko, R. V.Chepulskii) as well as short-period substitutional and interstitial honeycomb-lattice-based superstructures (T. M. Radchenko, V. A. Tatarenko) were determined.
V. M. Bugaev and V. A. Tatarenko elaborated a semi-phenomenological theory of interatomic interactions (taking into account strain-induced effects of atomic sizemismatch) within the interstitial solid solutions on the base of the metallic crystals with a polyatomic basis; a lot of quantitative information about energy and force parameters of interaction of C, N, O, H atoms in metals of II, III, IV, VII and VIII groups was obtained (V. A. Tatarenko, K. L. Tsinman).
For a wide range of finite solid solutions (particularly, based on the layered and close-packed crystals) as well as nonstoichiometric substitutional–interstitial phases of metallic oxides, subhydrides, nitrides, carbides, fullerites, invars and permalloys, the nonanalytically-described dispersion curves of the Fourier-components of energies of total interaction of substitutional or interstitial point defects in crystals of agiven structure and with stress-free surface are calculated, using methods of lattice statics and static concentration waves (M. O. Krivoglaz et al.), taking into semi-phenomenological account the ‘strain-induced’ (or ‘elastic’) interaction between defects, semi-empirically estimating the ‘chemical’ (or cohesive) interaction of interstitial ions (or substitutional defects),and model-calculating the energy parameters of magnetic interaction of substitutional atoms with arbitrary spin numbers (T. M. Radchenko, V. A. Tatarenko, K. L. Tsinman with colleagues from the Kyiv Nat’l Univ.).
The influences of temperature- and concentration-dependent magnetic and long-range anisotropic strain-induced interatomic interactions and short-range ‘electrochemical’ one on the atomic redistribution (ordering or decomposition) in the interstitial and substitutional alloys and their thermal and electronic-transport properties were studied (T. M. Radchenko, V. A. Tatarenko).
Based on calculations of the interatomic-interaction energy parameters, statistical-thermodynamic analysis in combination with the results of M?ssbauer research carried out in the Department of Physical Principles for Alloying of Steels and Alloys (V. G. Gavriljuk, V. M. Nadutov), V. M. Bugaev, V. A. Tatarenko, and K. L. Tsinman have investigated the nature of microinhomogeneities in a number of alloyed austenitic steels.
An analytical method providing comparatively high calculation accuracy of the short-range order parameters for alloys was proposed (R. V.Chepulskii); adequacy and efficiency of direct and indirect methods of the investigation of interatomic interactions and kinetics of relaxation of the short-range and long-rangeatomic orders in substitutional or interstitial close-packed solid solutions were analysed (T. M. Radchenko, V. A. Tatarenko, R. V. Chepulskii).
Effects of the size finiteness and complexity (nonprimitivity) of internal crystal structure as well as the size-mismatch and ‘blocking’ of the constituent atoms and their magnetism on the defect–defect interaction and thermodynamics and kinetics of superstructure formation of ordering solid solutions were revealed and analysed (V. A. Tatarenko, K. L. Tsinman,R. V. Chepulskii).
Using the statistical-thermodynamics and kinetics theories of the phase transformations and taking into account the long-range interatomic interactions, the classification scheme for discontinuities of the first kind at the centre of the first Brillouin zone of the reciprocal space for the solvent lattice is suggested for the Fouriercomponents of the ‘mixing’ energies of atoms in a finite solid solution (V. À. Tatarenko).
As ascertained, the nonanalytic character of the reciprocal-space description of energy parameters of the statistical thermodynamics and kinetics of ordering, spinodal decomposition or isostructural decomposition of finite solid solution is just caused due to the absence (‘gauge elimination’) of indirect strain-induced ‘self-action’ of the dissolved atoms (via the fields of the static distortions of the solvent) (V. A. Tatarenko).
V. M.Bugaev, V. A.Tatarenko, K. L. Tsinman, and R. V. Chepulskii, for the first time, analysed the qualitative peculiarities of state diagrams and anomalies in distribution of the interstitialatoms conditioned with a temperature dependence of theinteratomic-interaction energy parameters for the interstitialalloys.
The corresponding anomalies of configurationally dependentthermal and non-electronic transport properties of alloys, in particular, the experimentally observed nonmonotonity of a self-diffusion coefficient of carbon atoms in h.c.p. beryllium have been investigated (V. M. Bugaev, V. A. Tatarenko).
The effect of the interstitial impurity on the content of site vacancies in crystal has been quantitatively studied; the structural-entropy (in particular, ‘configurational’) and energy (including, ‘size-mismatch’) mechanisms of phenomena of thermally-activated and spontaneous changes of the preferential localization of impurity atoms in the crystal have been determined (V. M. Bugaev, V. A. Tatarenko, K. L. Tsinman).
The new mechanisms of polymorphic transformations conditioned by increase of the vacancies’ number (but not by the vibrational-mode softening) in interstitial alloys (A. M. Bobyr, V. M Bugaev, A. A. Smirnov) and of martensitic transformation in the ordering hybrid interstitial–substitutional alloys (V. A. Tatarenko, K. L. Tsinman) were suggested.
It is demonstrated that for the description of dissipative modulated structures (with finite and temperature-dependent period) in a distribution of vacancies over the irradiated crystal, a mechanism based on openness and nonequilibrium state of such a system and on nonlinear nature of bonds of vacancies with surroundings must be considered. Moreover, consistently with the methodological point of view, it should be considered the combination of contributions of both the (indirect) long-range ‘strain-induced’ interaction (particularly, of elastic character at long-range distances) and the dominant ‘direct’, comparably short-range‘ electrochemical’ interaction (basically, of cohesive nature at short-range distances) to the mutual influence of generated vacancies in presence of their dislocation-type sinks (O. V. Oliinyk, V. A. Tatarenko with colleagues from the Kyiv Nat’l Univ.).
Necessary thermodynamic conditions for the forming of the ‘modulated’ structures and their spatial period are formulated for case of inhomogeneous distribution of impurity particles within themesomorphous medium. These are conditioned by the temperature-dependent long-range indirect interaction between impurity particles and caused by the interference of the induced static fields of director distortions (V. A. Tatarenko with colleagues from the Kyiv Nat’l Univ.).
S. I. Olikhovskii and E. V. Kochelab with colleagues from the Kyiv Nat’l Univ. have developed physical model for the description of formation and evolution of microdefective structure of the supersaturated solid solution at heat treatment and have carried out dimensional and numerical analyses of the corresponding kinetic equations and the equations of mass transfer.
Using the state-of-the-art statistical-thermodynamic theory of short-range atomic order and kinematic theory of scattering by such order and displacements of atoms, the distribution patterns of diffuse-scattering intensity values over the reciprocal space forvarious lattices of finite substitutional and interstitial solid solutions with ‘free’ or strained surfaces are predicted, depending on the symmetry of sites or (octahedral or tetrahedral) interstices, respectively (V. A. Tatarenko, K. L. Tsinman,R. V. Chepulskii with colleagues from the Kyiv Nat’l Univ.).
Comparison of these patterns with corresponding experimental ones for those solutions makes possible both the identification of positions where solved atoms of any sort are located in the solvent of a given crystal structure and the diagnostics of the corresponding-character temperature and concentration dependences of the properties of solid solutions (electrical conductivity, heat capacity, etc.), taking into account the kinetics of atomic order relaxation (T. M. Radchenko, V. A. Tatarenko).
Ye. G. Len, V. V. Lizunov, I. M. Melnyk, T. M. Radchenko, V. A. Tatarenko with colleagues from the Kyiv Nat’l Univ. revealed influence of the changing of temperature and short-range and long-range magnetic orders on the pattern of scattering of different (electron, X-ray) waves in b.c.c.- and f.c.c.-lattice-based alloys (including strongly correlated electrons).Taking into consideration magnetism of both substitutional constituents, parameterization of interatomic and electron interactions in such ordering alloys is performed, and quantitative peculiarities of their state diagrams, including ferro-, antiferro-, and ferrimagnetic phases, are analysed.
O. I. Mitsek has improved the theory of magnetic properties of thin films and phase transitions as well as magnetotransport phenomena in magnetics, including nanoscale magnetic materials and structures.
The theoretical study of the electronic spectrum and nuclear magnetic resonance in metals containing dislocations as well as the statistical-mechanical analysis of the interacting-electron gas diamagnetism are carried out (I. M. Dubrovskyi).
The researchers of the department have developed: theory of nuclear magnetic resonance in ordering alloys (A. I. Nosar); classical theory of orientational effects (channelling phenomena and shadow effect) in single-crystalline substitutional and interstitial alloys (L. B. Kvashnina, O. I. Etingof, A. A. Smirnov); quantum theory of channelling in multicomponent systems and crystals with various-type defects (V. B. Molodkin, V. G. Novitskii, A. P. Kirilyuk).
A statistical dynamical theory of high-energy quasi-particles in multicomponent disordered systems, ordering alloys, and crystals with defects of various types was elaborated. Based on this theory, new fundamental physical phenomena were predictedand theoretically described for the first time. Namely, the phenomenon of extinction due to scattering on distortions, having been widely used today in many laboratories of the world, and the phenomenon of violation of the law of conservation of total integrated reflectance in single crystals (that was known from the kinematic theory of scattering), turning out to be a unique structurally sensitive and informative value, as well as the coherent effects of anomalous transmission and extinction for the incoherent component of the wave field of quasi-particles, which received multiple experimental confirmations and are widely used in many research centres in different countries (V. B. Molodkin, M. E. Osinovskii, S. I.Olikhovskii).
Based on the results obtained within the scope of the developed theory and predicted effects mainly stipulated by the multiplicity of the diffusion scattering, S. I. Olikhovskii, A. I. Nizkova, and Ye. M.Kislovskii under the directions of V. B.Molodkin have proposed a number of principally new methods of X-ray crystal diffractometry and created an original experimental base of qualitatively upgraded level for non-destructive diagnostics of types and quantitative statistical characteristics of crystal defects and alloys’ parameters, which has demonstrated the record-breaking indices of information value, sensitivity and rapidity of researches afore absent both in Ukraine and abroad.
V. B. Molodkin, S. V. Lizunova, V. V. Lizunov, and V. V. Molodkin have founded and explained in terms of physical reasonsthe unknown earlier phenomenon of enormous (by some orders of magnitude) strengthening of manifestation of defects in a pattern of multiple scattering. This one has a revolutionary importance for development of essentially new functional possibilitiesfor diagnostics.And as they have establish, it is possible due taking into account ‘switching’ of the dispersion mechanism of defects’ effect on the diffraction pattern that is effect not only on amplitude, but also on a scattered wave vector.
This one made possible not only to improve the structural sensitivity by some orders of magnitude, but also to construct a reasonable approach for the resolution of especially actual problem of multiparameter diagnostics by means of the combination of measurements of multiple-scattering patterns in chosen various diffraction conditions.
In 2013–2014, this founded phenomenon allowed to settle a problem of widely spread introduction into medical practice of the opportunity (constructed still in 1996) to increase sensitivity limit of X-ray diagnostics of neoplasms by one thousand times (from 5 mm to 5 microns) due to transition from traditional using of absorption to using of beams’ refraction as well as by means of the development of adequate theoretical model for diagnostics of noncrystalline objects. This theory quantitatively describes relationship between parameters of images, which one can get, and characteristics of neoplasms (taking into account a contribution of multiple-scattering effects, which are essential in these cases too).
V. B. Molodkin, S. I. Olikhovskii, Ye. M. Kislovskii, O. S. Skakunova, and S. V.Lizunova have carried out the generalization of the dynamical scattering theory for the case of multilayer structures with the complicated unit cell and with the nonuniform distributions of macrostrains and microdefects both between the layers and inside the layers.
Research team of the department is not aside from the threshold of a new era of dominance of carbon as one of the most common elements in nature. Traditions of studying the effects of defect configurations on scattering of different kinds of waves (including electronic ones), initiated by A. A Smirnov and developed by V. B. Molodkin, were continued in the works concerning with the structure formation, thermal and electronic-transport properties in functionalized graphene-based systems. In these works, for the first time, there were suggested possible ordered distributions of impurity atoms over the sites and interstices of graphene lattice, defined ranges of interatomic-interaction-energy parameters providing (low-temperature) stability for graphene-based substitutional and interstitial superstructures, revealed effects of correlation and ordering in the distribution of point (impurity atoms, vacancies) and linear (grain boundaries, atomic steps, dislocations) defects in graphenefor their separate and simultaneous presences within it (T. M. Radchenko, V. A Tatarenko with colleagues from the Kyiv Nat’l Univ.).
Particularly, the ordering of point defects can open a band gap in graphene energy spectrum, enhance graphene conductivity up to dozens (10–30) of times, and orientation correlation of linear defects can increase graphene conductivity up to 4–5 times. Therefore, in case of the simultaneous presence of both defect types, the ordering of some defects and correlation of other ones may improve graphene conductivity up to hundreds of times as compared with their random distribution (T. M. Radchenko, V. A Tatarenko with colleagues from the Kyiv Nat’l Univ.).
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