Abstract The effect of photoexcitation on the electrical conductivity of the interface between two polydiphenylenephthalide (PDP) polymer films is discovered. It is shown that ultraviolet radiation makes the main contribution to the generation of photoconductivity. Long-term relaxation of photoconductivity is observed after extinction of illumination. Based on electrophysical measurements and comparing

Abstract The features of the structure of domain walls in hexaferrite BaFe12O19 have been studied near the Curie temperature TC = 724 K. The studies have been performed on the single-crystal samples in ac magnetic field with frequencies of 73 MHz and 71 MHz, and in dc magnetic field in the range 0–0.25 kOe. In BaFe12O19 at temperature T1 = 716 K, the magnetic structure of domain walls is changed: the

Abstract The ellipsometric studies of the optical properties of intermetallic YFe2 and TbFe2 compounds have been performed in the wavelength range 0.22–15 μm, and a number of electronic and spectral characteristics have been determined. The nature of the interband light absorption in these materials is discussed based on a comparative analysis of the experimental and theoretical spectra of the optical

Abstract Temperature dependences of the thermal diffusivity and thermal conductivity in multiferroic materials BiFeO3, Bi0.90Sm0.10FeO3, and Bi0.90Eu0.10FeO3 were studied. Substitution of rare-earth ions of europium and samarium for bismuth ions in bismuth ferrite was found to decrease the phonon thermal conductivity in a wide temperature range. The decrease in the heat conductivity of bismuth ferrite

Abstract Phase transitions in the two-dimensional slightly diluted Potts model on a square lattice at q = 5 have been studied using the computer simulation method. The systems with linear sizes L × L = N, L = 10–120 are considered. It is shown based on the forth-order Binder cumulants and using the histogram analysis of the data that the introduction of nonmagnetic impurities to a spin system described

Abstract Room-temperature changes in the structure of a new diisopropylammonium chloride (C6H16ClN, DIPAC) molecular ferroelectric have been investigated by high-resolution cross polarization/magic-angle spinning nuclear magnetic resonance (CP/MAS NMR) and X-ray diffraction (XRD) methods. The NMR measurements are carried out using 13C nuclei. Depending on time and heat treatment, monoclinic ferroelectric

Abstract It is found using triboluminescence (TL) that nanocrystals of silicon (ncSi) with linear dimensions of about 4 nm are formed from a single crystal of silicon (Si) under friction. The time dependence of the intensity of TL signals is investigated. It consists of many superimposed signals. An analysis of their dynamics shows that nanocrystals are located on the microcrack faces formed during

Abstract Changes in the structure and properties of the Ni1 – xCuxFe2O4 ferrites-spinel magnetic nanoparticles depending on the Cu ion concentration (0 ≤ x ≤ 1.0) have been studied using Mossbauer spectroscopy. It has been found that, with the increasing of the Cu ion concentration, the structure of nanoparticles changes from the structure of reverse spinel (NiFe2O4) to that of mixed spinel (CuFe2O4)

Abstract The relaxation of the remanent magnetization of antiferromagnetically ordered ferrihydrite nanoparticles at the exchange bias effect implemented in these systems has been investigated. The magnetization relaxation depends logarithmically on time, which is typical of the thermally activated hoppings of particle magnetic moments through the potential barriers caused by the magnetic anisotropy

Abstract The formation of unoccupied electronic states and the boundary potential barrier during thermal deposition of tetracyanoquinodimethane (TCNQ) films to 7 nm in thickness on a (SiO2)n-Si surface has been studied. The electronic characteristics of the surface under study are measured by the total current spectroscopy (TCS) using a testing electron beam with energies from 5 to 20 eV above the

Abstract The heat capacity, thermal diffusivity, thermal conductivity, magnetization, and electrical resistance of the rapidly quenched Ni50Mn35Al2Sn13 alloy have been studied. Pronounced anomalies in the form of minima associated with magnetic and magnetostructural transformations have been observed on the temperature dependence of the thermal diffusivity. The behavior of thermal conductivity and

Abstract Linear and nonlinear dielectric properties of new organic ferroelectric diisopropylammonia iodide (DIPAI) introduced into porous aluminum oxide films have been studied in comparison with the properties of a bulk DIPAI. In DIPAI, in pores 300 and 60 nm in diameter, it has been found that the ferroelectric phase forms on heating and on cooling in the temperature range between two structural

Abstract— Samples of polycrystalline yttrium-iron garnet synthesized using radiation-thermal sintering and ceramic processing have been studied by the Mössbauer spectroscopy method. The best decomposition of the Mössbauer spectroscopy spectra of the research objects, which is a simulation of the experimental spectrum with five sextets, has been selected. An additional fifth sextet is caused by Fe3+

Abstract The (NH4)3VOF5 crystals have been synthesized and their homogeneity and single-phase structure has been established by the X-ray diffraction, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy studies. The investigations of the temperature dependences of specific heat, entropy, strain, and pressure susceptibility show the occurrence of three phase transitions caused by the

Abstract Luminescent (Zn,Cu,Ag)S:Eu3+ nanoparticles (quantum dots, QDs) are synthesized upon decomposition of thioacetamide metal complexes in methylmethacrylate during block polymerization upon heating. The QD formation is confirmed by a corresponding band in the optical absorption spectrum of polymer compositions. Photoluminescence of polymethylmethacrylate/(Zn,Cu,Ag)S:Eu3+ compositions manifests

Abstract Using Mössbauer spectroscopy on 57Fe nuclei and X-ray diffraction, the mechanism of mechanical alloying in a planetary ball mill of the Fe–Cr nanocrystalline system in a concentration range from 20 to 48 at % Cr has been studied in detail. It has been established that mechanical alloying occurs in one stage at a concentration of up to 30 at % Cr and in three stages at higher concentrations

Abstract Drawbacks of some methods known from the literature for determining four parameters of the Mie–Lennard-Jones pairwise interatomic potential as applied to crystals are pointed out. A new method for parametrization of the potential by thermoelastic properties of the crystal is proposed. The method determines the parameters by the best agreement of the calculated values with experimental data

Abstract Ni0.7 – xZn0.3MxFe2O4 (M = Mn2+, Co2+, and Cu2+; x = 0, 0.1, 0.3, 0.5, and 0.7) spinel-type ferrite were fabricated through citrate technique. The X-ray diffraction analysis disclosed the creation of the cubic phase spinel structure in all prepared samples, except for the high concentration of Mn (x = 0.7). As the concentration of dopant ions increased, the structural parameters, such as lattice

Abstract The origin of the low magnetization anisotropy of the textured bulk samples consisting of highly anisotropic (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) high-temperature superconductor crystallites has been investigated. It has been established that the observed anisotropy is determined by the disordering of Bi-2223 crystallites in the sample. The measured anisotropy of the textured sample makes it possible

Abstract The effect of temperature conditions on the formation of copper active sites obtained by solid state ion exchange between copper chloride and H-mordenite zeolite using X-ray absorption spectroscopy in near-threshold (XANES) and extended (EXAFS) spectral regions behind the copper K-edge measured in in-situ conditions of the reaction at temperatures varying from room temperature to 400°C. The

Abstract We studied the luminescence of CdTe layers with a nominal thickness of one, two, four, and eight monolayers (MLs) grown by atomic layer deposition in a ZnTe matrix. The layers with a thickness of one and two monolayers exhibit the properties of homogeneous layers, while the layers with a thickness of four and eight monolayers are planar arrays of quantum dots (QDs). The sizes of QDs and their

Abstract The frequency dependences of the group velocity and the damping of a magnetoelastic surface wave have been studied at various values of an external magnetic field and various angles of propagation. The group velocity bursts are observed at frequencies, at which peaks of surface wave damping take place. The behavior of a surface magnetoelastic wave is also studied near the orientation phase

Abstract The shape memory effect is demonstrated in a ferromagnetic microsample of the Ni50Mn18.5Ga25Cu6.5 Heusler alloy. The 23 × 1.28 × 4-μm microsample has been fabricated using the technology of a focused ion beam. The elastic deformation in the martensite phase is found to be higher than the shape memory effect based on the permanent strain due to twinning. The maximum value of the shape memory

Abstract The specific heat and the dielectric permittivity of Bi0.8Ho0.2FeO3 multiferroics have been studied in the wide temperature range 300–750 K. The doping with rare-earth element holmium is found to lead to substantial changes in the temperature dependences of specific heat Cp and dielectric permittivity ε' at high temperatures. The additional contribution to the specific heat is shown can be

Abstract Ribbons of alloys of the quasi-binary TiNi–TiCu system with 25, 30, 35, and 40 at % copper were fabricated by planar flow casting at a cooling rate of 106 K/s. The thickness of the ribbons was 30–50 μm, and their width was 10–20 mm. The structure and phase transformations of alloys were studied using electron microscopy, X-ray diffraction, and differential scanning calorimetry. It was found

Abstract Ab initio calculations of the atomic and electronic structure and cohesion energy of Si60C60 fullerene-like clusters have been performed. For the first time, a model of a two-layer cluster Si12C12@Si48C48 with mixed sp2/sp3 bonds has been built. Ab initio calculations were carried out in the framework of the theory of the electron density functional and the hybrid functional B3LYP. The stability

Abstract Magnetization reversal of a hard/soft magnetic bilayer in an external magnetic field has been studied by the Monte Carlo method. The magnetization reversal curves of a magnetic bilayer have been built at various thicknesses of the soft magnetic layer. The effects of the intralayer exchange interaction and the anisotropy constant of the soft magnetic layer on the magnetization reversal have

Abstract The pressure dependences of electrical resistance, Hall coefficient, charge carrier mobilities, and magnetoresistance of the Cd3As2–20 mol % MnAs composite are investigated at pressures up to 9 GPa. The pressure dependences of all the listed properties exhibit features related to phase transitions. The presence of pressure-induced negative magnetoresistance is registered.

Abstract The structure and magnetic properties of FeRh1 – xIrx alloys (x = 0.5, 0.625, 0.75, 0.875, and 1) are investigated by first-principles methods using the VASP software package. Two types of structures (CuAu and CsCl) are examined in the study. The equilibrium lattice parameters, total energy, and magnetic moment, as well as the total and partial densities of states for the Fe–Rh–Ir system,

Abstract Chromium films with a thickness of 10–40 nm deposited onto silicon substrates by magnetron sputtering are subjected to the action of electric current induced by the tip of an atomic force microscope (AFM) cantilever in air under regular environmental conditions. The melting process at the nanoscale, electric field-induced migration of material, and the chemical reaction of chromium oxidation

Abstract We present the results of diffraction studies and the electromagnetic (EM) field distribution in a microsphere of vanadium dioxide (VO2) before and after the metal–semiconductor phase transition (MSPT) is presented. As a result of the calculations, it has been shown that after the phase transition point in VO2 (T > Tc), the EM wave field practically does not pass into the microsphere, almost

Abstract The elastocaloric effect (ECE) is studied in samples of rapidly quenched ribbons of a Ti2NiCu alloy at a periodic action by a mechanical stress to 300 MPa at a frequency to 50 Hz. ECE is maximal near the temperatures of a first-order thermoelastic martensitic phase transition. The ECE maximum is observed in a point corresponding to the completion of the reverse martensitic transition (T =

Abstract Time dependences of permittivity and optical transmission in the Pb(Mg1/3Nb2/3)O3–xPb(Zr0.53Ti0.47)O3 (x = 16, 23, and 33%) transparent ferroelectric ceramics are studied in the electric fields of 0 < E< 6 kV/cm. It is shown that even in fields, which are less than the coercive field, a sharp decrease in the permittivity occurs in compounds with x equal to 16 and 23% in a short time, while

Abstract A nonlinear 1D chain with nonlocal interaction has been considered. A nonlocal equation describing the propagation of envelope waves in the medium has been obtained using the multiscale decomposition method. The properties of the resulting equation have been studied and exact soliton-like solutions have been constructed using the Darboux transformation method.

Abstract Processes of molecular relaxation in Li2SO4, Na2SO4, and K2SO4 sulfates; Li2CO3, Na2CO3, and K2CO3 carbonates; NaClO4 and KClO4 perchlorates; and Ca(NO3)2, Sr(NO3)2, and Ba(NO3)2 nitrates have been investigated by Raman spectroscopy. It is established that the first-order phase transitions in these systems have a stretched character (structural phase transitions in sulfates, carbonates, and

Abstract The thermal stability of recently predicted carbinofullerenes C38, C62, and C64 was examined using the molecular dynamics method. Their decomposition channels and temperature dependences of the lifetime were characterized. The activation energies and frequency factors in the Arrhenius law were determined. New isomers of carbinofullerenes C38 and C62, which are more thermally stable than the

Abstract The tensile curves of ultrafine-grained (UFG) aluminum structured by high pressure torsion (HPT) technique have been obtained at 4.2 and 77 K for the first time as well as the temperature dependence of its yield strength in the range 4.2–300 K. The analysis of the results in correlation with microstructure parameters and comparison with the results of such studies for UFG aluminum structured

Abstract For the first time, the dependences of the strain energy and the band gap of achiral nanotubes obtained by folding monolayers of gallium(II) sulfides and selenides on their diameter have been calculated nonempirically. The calculations were performed using the CRYSTAL17 software package using an atomic basis set within the hybrid density functional theory with a thirteen-percent Hartree–Fock

Abstract The variation of low-energy slow secondary electron emission from the surface of relief structures (bumps) during their prolonged scanning in a low-voltage scanning electron microscope is estimated. The variation nature depends on the bump region profile, which is especially complex near relief structure angles. As a result, corresponding curve portions of the bump video signal, which results

Abstract The multicomponent responses of photoreflectance spectrum is experimentally studied using selective phase analysis. After several experimental tests, the phase diagram of vanadium-doped GaAs|GaAs in region of fundamental energy shows only one component. On the other hand, the PR spectrum of GaAsBi|GaAs structure reveals at least two contributions relative to fundamental band–band transition

Abstract The paper discusses the features of supercooled water thin film of width d = 3.97 nm contained by the perfect graphene layers and crystallizing under external stationary electric field. It was found that the electric field applied perpendicular to graphene layers impedes structural ordering, while the electric field applied in lateral direction contributes to formation of the cubic ice (Ic)

Abstract The specific heat and the magnetocaloric effect of intermetallic LaFe11.2 – xMnxCo0.7Si1.1 (x = 0, 0.1, 0.2, 0.3) compounds have been measured in the temperature range 80–300 K in magnetic fields up to 8 T. The magnetocaloric effect (MCE) is estimated by two methods: the direct method in cyclic magnetic fields and also indirect method from the data on the specific heat. An increase in the

Abstract The thermal diffusivity and thermal conductivity of multiferroics Bi1 – xHoxFeO3 (x = 0–0.20) have been studied in the high-temperature region of 300–1200 K. It is established that alloying with the rare-earth element (holmium) strongly increases the specific heat in a wide temperature range T > 300 K and significantly changes temperature anomalies of the thermal diffusion and thermal conductivity

Abstract Amorphous metallic foams are prospective materials due to unique combination of their mechanical and energy-absorption properties. In the present work, atomistic dynamics simulations are performed under isobaric conditions with the pressure p = 1.0 atm in order to study how cooling with extremely high rates (5 × 1013–5 × 1014 K/s) affects the formation of pores in amorphous titanium nickelide

Abstract The direct measurements of the magnetocaloric effect ΔTad in the Heusler alloy Ni49.3Mn40.4In10.3 have been carried out in cyclic magnetic fields with amplitudes to 8 T. The maximum values of the magnetocaloric effect are 5.29 K in the martensite–austenite transition region and 3.39 K in the region of the magnetic phase transition in the austenite phase. A long-term action of a cyclic magnetic

Abstract The thermodynamic properties of the models of magnetic dendrimers were studied by the Monte Carlo method. The system state density is calculated; the ground state structures are determined. The temperature dependences of magnetization m, entropy S, internal energy E, and heat capacity C are calculated. It is shown that in the investigated model of dendrimer, the effect of the surface sites

Abstract The interaction of an electromagnetic radiation with electric dipole active spin modes in a multisublattice antiferrodielectric is shown to possibly lead to anomalous (negative) spatial shift of a light beam when an electromagnetic wave is incident on the interface with an isotropic dielectric medium.

Abstract The Monte Carlo method is used to study phase transitions in disordered two-dimensional Potts models in which disorder is realized as nonmagnetic impurities. The temperature dependences of the thermodynamic parameters have been calculated for specific heat C, susceptibility χ, and fourth-order Binder cumulants in the dependence on spin concentration p. The calculations have been performed

Abstract In Sr9 – xMxTm(VO4)7 system, solid solutions with M = Ca (0 ≤ x ≤ 2) and M = Pb (0 ≤ x ≤ 1) have been prepared by solid-phase synthesis at 1373 K. At room temperature, the single-phase samples are isostructural to the Ca3(VO4)2 ferroelectric (space group R3c, Z = 6). The materials have been characterized by methods of the X-ray phase analysis (XPA), the second harmonic generation (SHG), and

Abstract Phosphate solid solutions based on the whitlockite family Ca9 – xMxDy(PO4)7 (M = Zn2+ or Mg2+) have been obtained. The samples have been investigated by a combination of the methods, such as X‑ray diffraction analysis, second optical harmonic generation, and luminescence spectroscopy. It is established that the unit-cell symmetry change (R3c → \(R\bar {3}c\)) in the solid-solution series with

Abstract Within the variational spin density functional method, the description of the temperature and ferromagnetic ordering effects on the adsorption of atoms of transition metals placed on paramagnetic substrates at formation of a monolayer film of FexNi1 – x alloy depending on the alloy component concentration and the coating parameter θ has been accomplished for the first time. The influence of

Abstract The results of investigation of functional characteristics of the Mn2NiGa Heusler alloy prepared by argon-arc melting are presented. Its electric resistance, magnetization, magnetocaloric and shape memory effects were studied using direct experimental techniques in a wide temperature range 100–400 K. The inverse magnetocaloric effect, which does not reach saturation in pulsed magnetic fields

Abstract The temperature–frequency spectra of the complex dielectric permittivity of the LuFe2O4 multiferroics have been studied in the temperature range 100–400 K at frequencies 20 Hz–120 MHz. It is found that the temperature coefficient of the dielectric permittivity changes its sign and the ac conductivity has maxima and minima in the temperature range ~150–350 K and in the frequency range ~30–120

Abstract Several complex theories explaining the phenomenon of negative magnetoresistance (NMR) are discussed, observed in insulating diluted granular multilayers Co80Fe20(t)|Al2O3. In fact, this investigation is re-analyzing the experimental measurements of Co80Fe20 with low nominal thickness t = 0.7 nm of granular layers obtained earlier. Two theories such as quantum interference model and localized

Abstract We synthesized diamond particles with germanium-vacancy color centers on a germanium substrate by hot-filament chemical vapor deposition. The formation of color centers occurred during the growth of diamond particles by the introduction of germanium atoms formed by the etching of a crystalline germanium wafer with atomic hydrogen. The conditions of the vapor phase deposition, which affect

Abstract The magnetic and magnetocaloric properties of Heusler Ni2 + xMn1 – xGa alloys (x = 0.16, 0.18, and 0.3) have been studied using a model based on the Malygin theory of smeared phase transitions, the Bean–Rodbell theory of first-order phase transitions, and the mean-field theory. The temperature dependences of strain, magnetization, and isothermal change in entropy of these alloys have been

Abstract The features of the composition, crystal, and magnetic structure of Ti-substituted barium hexaferrite BaFe12 – xTixO19 (0.25 ≤ x ≤ 1.5) are studied by Mössbauer spectroscopy, vibration magnetometry, X-ray diffraction, and simultaneous thermal analysis. Bounded heterovalent isomorphism implemented by the scheme 2Fe3+ → Ti4+ + Fe2+ while retaining the charge balance is established when Fe3+

Abstract A numerical Monte Carlo study has been performed on the influence of various initial states, easy-axis-type magnetic anisotropy, and structural defects on a nonequilibrium critical behavior of the classical three-dimensional Heisenberg model. An analysis of the time dependence of the magnetization and the autocorrelation function for the isotropic Heisenberg model shows substantial influence

Abstract Influence of hydrogenation on the microstructural parameters, surface topology, and temperatures of magnetic phase transitions in Dy2Fe10Al7 was studied. Thermomagnetic properties in the obtained hydride Dy2Fe10Al7H3.2 were also investigated. Hydrogenation was found not to change the Curie point of the compound Dy2Fe10Al7, but at the same time it affects remarkably the temperature of the magnetic

Abstract A vortex system of the Bi-2212 superconductor in an external magnetic field linearly increasing at different rates has been numerically simulated using the Monte Carlo method. The effect of the concentration and distribution of pinning centers on the penetration of the magnetic flux has been studied. Features of the flux penetration have been observed and described in terms of the vortex system