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At the temperature 293 K, the influence of two types of nanoimpurities (carbon multiwall nanotubes and C60 fullerene) both separately and together on the dielectric properties of Shell oil transformer oil has been studied. It has been shown that these impurities do not significantly effect on the value of the dielectric permittivity of Shell oil, but more significantly increase its conductivity. It has been found that in the presence of nanotubes inside Shell oil, the dependence of its electrical conductivity on the fullerene concentration is nonmonotonic. The samples with the fullerene concentration 100 ppm have the highest conductivity. At the fullerene concentration 300 ppm, the conductivity of Shell oil with the impurities of carbon nanotube and C60 fullerene becomes almost equal to the electrical conductivity of Shell oil only with the impurities of carbon nanotubes. It has been suggested that C60 fullerene can be used to reduce the electrical conductivity of Shell oil with magnetic nanoparticles required to increase the cooling efficiency of transformers under the action of their own magnetic field.

Cu1–xAgx)7GeSe5I-based ceramics were prepared by pressing and sintering from the micro- and nanopowders. The ceramic samples were investigated using microstructural analysis. The microhardness was measured applying the indentation method with use of the Vickers pyramid. It has been shown that the microhardness of (Cu1–xAgx)7GeSe5I-based ceramics decreases with copper content decrease at Cu+→Ag+cationic substitution. The compositional dependences and size effects of microhardness inherent to (Cu1–xAgx)7GeSe5I-based ceramics have been analyzed. The size effects of microindentation have been interpreted within the framework of the gradient theory of plasticity.

High-quality single crystals of Ag7(Si1–xGex)S5I (x = 0.2, 0.4, 0.6, 0.8) solid solutions are grown from the solution–melt by vertical zone crystallization method. The measurements of electrical conductivity of Ag7(Si1–xGex)S5I solid solutions were performed using the impedance spectroscopy method within the frequency range from 10 Hz up to 2·106 Hz and temperature interval 293–383 K. Ionic and electronic components of electrical conductivity, as well as their ratios, were determined using the Nyquist plots.

Searching for novel low-cost and eco-friendly materials for energy conversion is a good way to provide widespread utilization of thermoelectric technologies. Herein, we report the thermal behavior, phase equilibria data, and thermoelectric properties for the promising argyrodite-based Cu7P(SxSe1-x)6 thermoelectrics. Alloying of Cu7PSe6 with Cu7PS6 provides a continuous solid solution over the whole compositional range, as shown in the proposed phase diagram for the Cu7PS6-Cu7PSe6 system. As a member of liquid-like materials, the investigated Cu7P(SxSe1-x)6 solid solutions possess a dramatically low lattice thermal conductivity, as low as ∼0.2-0.3 W m-1 K-1, over the entire temperature range. Engineering the configurational entropy of the material by introducing more elements stabilizes the thermoelectrically beneficial high-symmetry γ-phase and promotes the multivalley electronic structure of the valence band. As a result, a remarkable improvement of the Seebeck coefficient and a reduction of electrical resistivity were observed for the investigated alloys. The combined effect of the extremely low lattice thermal conductivity and enhanced power factor leads to the significant enhancement of the thermoelectric figure of merit ZT up to ∼0.75 at 673 K for the Cu7P(SxSe1-x)6 (x = 0.5) sample with the highest configurational entropy, which is around twice higher compared with the pure selenide and almost four times higher than sulfide. This work not only demonstrates the large potential of Cu7P(SxSe1-x)6 materials for energy conversion but also promotes sulfide argyrodites as earth-abundant and environmentally friendly materials for energy conversion.

The influence of two types of nano-impurities MF1 and MF2 on the dielectric properties of Shell oil transformer oil at the temperature 293 K has been studied. It has been shown that these magnetic impurities have no significant effect on the dielectric permittivity value of Shell oil, but more significantly increase its conductivity, in so doing, the impurity MF1 increases the conductivity of transformer oil 4 times larger than the impurity MF2. It has been ascertained that the low-frequency dielectric relaxation appearing in the studied samples can be described by the Cole–Cole equation. The parameters of this relaxation process and the influence of different types of magnetic impurities on them have been estimated.

Ceramic samples based on the microcrystalline powders (Cu1–хAgx)7GeSe5I (x = 0, 0.25, 0.5, 0.75, 1) were prepared by pressing them at the pressure close to 400 MPa and subsequent annealing at 873 K for 36 hours. Using the microstructural analysis, the average size of microcrystallites of these samples was determined. Investigation of electrical conductivity of ceramics based on (Cu1 хAgx)7GeSe5I solid solutions was carried out using the method of impedance spectroscopy in the frequency range from 10 Hz to 3×105 Hz and within the temperature range 293...383 K. Analysis of the Nyquist plots allowed determining the contributions of ionic and electronic components to the total electrical conductivity. The temperature dependence of ionic and electronic conductivity in Arrhenius coordinates is linear, which indicates their thermoactivation character. The compositional behaviour of ionic and electronic conductivity, as well as their activation energies have been studied. Their nonlinear character can be explained by the complex process of recrystallization and Cu+ ↔ Ag+ cation substitution within the cationic sublattice.

The single crystals of quaternary halogen Ag6PS5I were grown from the solution–melt by means of a vertical zone crystallization method. The crystal structure has been ascertained using the Rietveld method. Investigation of electrical conductivity was carried out using the impedance spectroscopy technique within the frequency range 1·101 – 3·105 Hz and temperature interval 293–383 K on gold contacts applied by chemical deposition from solution. Ionic (1.79·10-3 S/cm) and electronic (1.64·10-6 S/cm) components of electrical conductivity have been determined using the Nyquist plots. The mechanism of ionic conductivity for Ag6PS5I single crystal has been proposed which can be considered as ion diffusion through “channels” Ag2–Ag2.

In the concept of superspatial symmetry the crystal structure of Cu7SiS5I and Ag7SiS5I superionic conductors has been analyzed. To calculate the phonon spectra, the model of FCC superlattice (8а, 8а, 0; 8а, 0, 8а; 0, 8а, 8а) in the metric of protocrystal (а, а, 0; а, 0, а; 0, а, а) has been developed. For the developed model, the general (3+3)-dimensional basis, the array of modulation vectors and mass modulation functions have been presented. The model calculations of phonon spectra dispersion for Cu7SiS5I and Ag7SiS5I crystals in schemes with various partial occupation of crystallographic orbits by Cu(Ag) atoms have been performed. The dispersion dependences of phonon spectra for Cu7SiS5I and Ag7SiS5I crystals in the high-symmetric directions of Brillouin zone have been presented. The genesis of phonon branches of vibrational spectra has been analyzed.

Within the frequency range 10–1–105 Hz under the temperatures 293–295 K, the dielectric properties of a planar-oriented nematic liquid crystal 6CB with the embedded of 0.1% superionic conductor Ag7GeS5I nanoparticles have been investigated. It has been shown that for the whole temperature range, the obtained frequency dependences of the components ε' and ε" composing the complex dielectric function can be separated into 3 sections. The dispersion of ε' and ε" for the lowest frequencies (less than 102 Hz) is described by the Debye equation and is caused by the rotation of the dipole moments of LC molecules under the action of electric field within the angles corresponding to the fluctuations of the order parameter in a thin near-electrode layer. It has been shown that the temperature dependence of the value of inverse relaxation time for such a process is described by straight lines in the Arrhenius coordinates within each mesophase. The activation energies for these dependences have been estimated for each mesophase. It should be noted that within the middle range of frequencies (102–104 Hz), for each temperature, one can separate a section where the magnitude of the conductivity does not depend on the frequency. The conductivity in these sections is equal to the conductivity of LC with the nanoparticles. It has been found that both the value of inverse relaxation time and the value of conductivity change according to the Arrhenius law on the temperature. The activation energies for the temperature dependence of conductivity and the temperature dependence of inverse relaxation time have been estimated, and it has been shown that they are close (for the nematic phase) and equal (for the isotropic phase). In the highest frequency section of the dielectric spectrum (104–105 Hz), the conductivity of the mixture 6CB + 0.1 wt.% Ag7GeS5I changes according to the power law of the frequency. It has been suggested that a sharp increase in the conductivity of 6CB with nanoparticles of the superionic conductor Ag7GeS5I at the concentration 0.1 wt.% was caused by the sharp increase in the electronic component of conductivity through Ag7GeS5I nanoparticles.

(Cu1–хAgx)7SiS5I mixed crystals were grown using the vertical zone crystalliza-tion method, they have been shown to crystallize in cubic structure (). The diffuse reflection spectra for the powders of (Cu1–хAgx)7SiS5I mixed crystals were measured at room temperature. Refractive indices and extinction coefficients for (Cu1–хAgx)7SiS5I mixed crystals were obtained from spectral ellipsometry measurements. A nonlinear decrease of the energy pseudogap and a nonlinear behavior with the maximum of refractive index have been revealed with increasing the Ag content. The dispersion of refractive indices of (Cu1–хAgx)7SiS5I has been described in the framework of different models.

Size-selected series of Ag–In–S and Ag–In–S:Zn quantum dots (QDs) with intense broadband photoluminescence were synthesized in aqueous solutions in the presence of glutathione and mercaptoacetic acid. The bands observed in their Raman spectra are assigned to the corresponding bond vibrations. A noticeable bandgap broadening with addition of a zinc agent at the second stage of the synthesis procedure implies incorporation of Zn into the QD lattice rather than the QD surface passivation by a ZnS shell. The stability of the synthesized QD solutions during long-term storage at room temperature is discussed.

(Ga0.3In0.7)2Se3 films were deposited by the thermal evaporation technique. As-deposited (Ga0.3In0.7)2Se3 films were irradiated using wideband radiation of Cu-anode X-ray tube at different exposure times. The spectral dependences of refractive index and extinction coefficient were measured by the spectral ellipsometry technique. The optical transmission spectra of X-ray irradiated (Ga0.3In0.7)2Se3 films were studied depending on irradiation time. Parameters of Urbach absorption edge for X-ray irradiated (Ga0.3In0.7)2Se3 thin films were determined and compared with nonirradiated film. The spectral dependences of refractive indices of non-irradiated and X-ray irradiated (Ga0.3In0.7)2Se3 films are described in the framework of Wemple and DiDomenico model. TThe variation of the parameters of Wemple and DiDomenico model for non-irradiated and X-ray irradiated (Ga0.3In0.7)2Se3 films was discussed.

The promising class of the environment-friendly thermoelectrics is the copper-based argyrodite-type ion-conducting crystals exhibiting just extraordinary low thermal conductivity below the glass limit associated with the molten copper sublattice leading to a softening of phonon modes. To explain why the argyrodite structure containing copper ions favors the low thermal conductivity, we have utilized the ab initio calculations of the electron, phonon, and thermoelectric properties of Cu7PS6 crystal in the framework of the density functional and Boltzmann transport theories. To obtain the reliable thermoelectric properties of Cu7PS6, we take into account the dependence of the electron effective mass m* on the redundant carrier concentration n. We propose to use the Burstein-Moss effect for the calculation of the electron effective mass m* of a semiconductor. We have found the strong nonlinear character of copper atom vibrations in Cu7PS6 which exceeds substantially the similar values for phosphorous and sulfur atoms. The large vibration nonlinearity of the copper atoms found in Cu7PS6 explains the diffusion-like heat transfer and the relatively low coefficient of the lattice thermal conductivity (κ = 0.7 W/(m⋅K)), which is favorable to achieve the large thermoelectric figure of merit.

Ceramic samples on the basis of nanocrystalline powders $\mathrm{c}_{\mathrm{u}1-\mathrm{x}} A \mathrm{g}_{\mathrm{x}})_{7}$GeSe5I(x=0,0.25,0.5,0.75,1) were made by cold pressing technique at a pressure of $\sim$0.4 GPa with further annealing during 36 hours at 873 K. The size of ceramic materials crystallites is determined by the method of microstructural analysis. Investigation of electrical properties of ceramics based on (Cu1-xA$\mathrm{g}_{\mathrm{x}})_{7}$GeSe5I mixed crystals were carried out by the method of impedance spectroscopy in the temperature range 293-383K and in the frequency range from 10 Hz to 300 kHz. Analysis of Nyquist plots allowed to determine the ionic and electronic components of electrical conductivity, the temperature dependence of which in Arrhenius coordinates has a linear character, which indicates their thermoactivation mechanism. Compositional behaviour of both components of electrical conductivity (ionic and electronic) and their activation energies were estimated. Their nonlinear character is explained by both the complex process of recrystallization and Cu+$\leftrightarrow$ Ag+ cationic substitution.

The structure and optical properties of Bridgman-grown (Cu6PS5Br)1-x(Cu7PS6)x mixed crystals are reported. X-ray diffraction data reveal a face-centred cubic lattice ( F 4 ¯ 3 m space group) for Cu6PS5Br-rich crystals (0

Searching for novel low-cost and eco-friendly materials for energy conversion is a good way to provide widespread utilization of thermoelectric technologies. Herein, we report the thermal behavior, phase equilibria data, and thermoelectric properties for the promising argyrodite-based Cu

Model calculations of the phonon dispersion dependencies have been carried out for the CU 7 GeSe 5 I and Ag 7 GeSe 5 I superionic crystals. For the first time, within the framework of the superspace symmetry concept the CU 7 GeSe 5 I and Ag 7 GeSe 5 I crystals have been investigated and their (3+d)-dimensional model descriptions have been developed. The description of the models of the considered structures was reduced to the construction of the modulation vectors arrays, definition of the mass modulation functions, construction of the generalized dynamic matrix as a superposition of the dynamic matrices of monoatomic structures; and the eigenvalues of the dispersion dependencies of the single particle perturbations have been obtained for the high symmetry directions of the Brillouin zone. The dynamic matrices $D_{a\beta}(k+q_{i})$ of the protocrystals were calculated taking into account a certain number of the force constant of the influential coordination groups.

Thermal evaporation technique was used to deposite $\gamma_{1}$ films. As-deposited thin films were irradiated by means of wideband radiation of Cu-anode X-ray tube at different exposition times. Spectral ellipsometry measurements were conducted in order to obtain refractive index and extinction coefficient dispersions. Optical transmission spectra of X-ray irradiated $(\text{Ga}_{X}\text{In}_{1\rightarrow x})_{2}\text{Se}_{3}$ films were measured depending on irradiation time. Parameters of Urbach absorption edge for X-ray irradiated $(\mathbf{Ga}_{0.1}\mathbf{In}_{0.9})_{2}\mathbf{Se}_{3}$ films were studied. The investigation revealed the nonlinear decrease of energy pseudogap together with nonlinear increase of Urbach energy and refractive index, as well as the increase of X-ray irradiation time.

The results of microhardness studies of $\mathbf{Ag}_{6+\mathbf{x}}(\mathbf{P}_{1-\mathrm{x}}\mathbf{Ge}_{\mathbf{x}})\mathbf{S}_{5}\mathbf{I}$ single crystals are presented. Established that with increasing the depth of the imprint of the Vickers indenter, a direct indentation size effect (ISE) is observed. Approximation and interpretation of the obtained results within the gradient theory of plasticity are carried out. The parameters of the geometrically necessary dislocations (GNDs) model are determined.

This work investigates band structure, total and partial densities of states, and full complex of optical functions of Ag 7 GeS 5 I crystal belongs to the family of compounds with an argyrodite structure using the density functional theory (DFT) improved by an on-site Coulomb self-interaction potential $(\mathbf{DFT}+\boldsymbol{U})$ . The lowest energy electronic transition occurs at the center of the Brillouin zone. The band gap energy is estimated in the DFT-LDA+U approximation, which is $E_{\mathbf{gd}}=1.68\mathbf{eV}$ ·

Ceramic samples based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$ nanocrystalline powders were manufactured by pressing them at $\sim 400$ MPa pressure and subsequent annealing at 973 K during 36 hours. Investigations of electrical conductivity of ceramics based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$ solid solutions were carried out by the method of impedance spectroscopy in the frequency range from 10 Hz to $2\times 10^{6}$ Hz and in the temperature range 292-383 K. It is established that with increasing the content of silver atoms in ceramic samples based on $(c_{u1-x}Ag_{x})_{7}SiS_{5}I$, the ionic component of electrical conductivity increases nonlinearly, while electronic component decreases nonlinearly, and their ratio increases nonlinearly and for $Ag_{7}SiS_{5}I$ exceeds 60000.

$\left(G a_{0.2} \operatorname{In}_{0.8}\right)_{2} \mathrm{Se}_{3}$ films were deposited by the thermal evaporation technique. As-deposited thin films were irradiated using wideband radiation of Cu-anode X-ray tube at different exposition times. The spectral dependences of refractive index and extinction coefficient were measured by the spectral ellipsometry technique. The optical transmission spectra of X-ray irradiated $\left(G a_{0.2} \operatorname{In}_{0.8}\right)_{2} \mathrm{Se}_{3}$ films were studied depending on irradiation time. Parameters of Urbach absorption edge for X-ray irradiated $\left(G a_{0.2} \operatorname{In}_{0.8}\right)_{2} \mathrm{Se}_{3}$ films were determined. The nonlinear decrease of energy pseudogap as well as nonlinear increase of Urbach energy and refractive index with increase of X-ray irradiation time are revealed. The spectral dependences of refractive indices of non-irradiated and X-ray irradiated $\left(G a_{0.2} \operatorname{In}_{0.8}\right)_{2} \mathrm{Se}_{3}$ films are described by different dispersion relations.

Thermal evaporation technique was used to deposit (Ga0.1In0.9)2Se3 thin films. The optical transmission spectra of (Ga0.1In0.9)2Se3 thin film were studied in the temperature range 77-300 K. Temperature behaviour of the Urbach absorption edge as well as the temperature dependencies of the energy pseudogap and Urbach energy were investigated. The influence of different types of disordering on the optical properties of (Ga0.1In0.9)2Se3 thin film was discussed. Optical parameters of (Ga0.1In0.9)2Se3 thin film and single crystal were compared.

The ceramics based on (Cu0.5Ag0.5)7SiS5I solid solution of superionic conductor with argyrodite structure were prepared by using the powders with different particles size. The structural studies of powders were performed by XRD technique, while the ceramic samples with different average size of the crystallites were investigated by microstructural analysis. The total electrical conductivity of ceramic samples was measured by impedance spectroscopy in the frequency range from 10 Hz to 2×106 Hz and temperature interval from 292 K to 383 K. The contributions of ionic and electronic components into the total electrical conductivity were separated as well as their temperature behavior was studied. The dependences of ionic and electronic conductivity and their activation energies on average size of the crystallites in (Cu0.5Ag0.5)7SiS5I-based ceramic samples were investigated.

Single crystals of (Cu1-хAgx)7GeS5I solid solutions were grown by vertical zone crystallization method. XRD studies have shown that they crystallize in face-centered cubic lattice of the argyrodite structure (space group F 4 ¯ 3 m , Z = 4). Structural studies were performed on the basis of original structure model by means of Rietveld refinement method. Electrical measurements were carried out in the temperature interval 300–360 K and in the range of frequencies 10 Hz–10 GHz. Temperature and frequency dependences of electrical conductivity were analyzed. Influence of cation substitution on the electrical conductivity as well as relationship between structural and electrical properties of (Cu1-хAgx)7GeS5I solid solutions were studied.

The (Ga0.3In0.7)2Se3 films deposited by the thermal evaporation technique are annealed in the inert atmosphere (argon) for 1 h at temperatures of 50, 100, and 150 ∘C. The spectral ellipsometry is applied for measuring the spectral dependences of the refractive and extinction coefficients of as-deposited and annealed (Ga0.3In0.7)2Se3 films. The optical transmission spectra, as well as the optical absorption spectra of (Ga0.3In0.7)2Se3 films, are studied depending on the annealing temperature. The optical absorption edge for annealed (Ga0.3In0.7)2Se3 films is shifted to the short-wavelength region and broadens, as the annealing temperature increases. Parameters of the Urbach absorption edge are determined for as-deposited and annealed (Ga0.3In0.7)2Se3 films. The spectral dependences of the refractive index are analyzed in the framework of the Wemple–DiDomenico model. The nonlinear increase of the energy pseudogap, Urbach energy, and refractive index with the annealing temperature are revealed.

Introduction . Cu 6 PS 5 I crystals belong to a big family of compounds with argyrodite structure. They are characterized by high ionic conductivity. That’s why these materials are promising for creation of different type of modern devices such as batteries, supercapacitors, electrochemical sensors, etc. Studies of the influence of external factors on physical properties of Cu 6 PS 5 I materials are important to predict endurance, wear resistance and safety of devices made on their basis. Purpose . The purpose of the paper is to investigate the influence of X-ray irradiation on the optical properties of Cu 6 PS 5 I-based thin films as well as to perform the quantative and qualitative evaluation of the changes that have taken place in the structure “film-substrate” as a result of X-ray irradiation. Methods . Cu 6 PS 5 I-based thin films were deposited onto silicate glass substrates by non-reactive radio frequency magnetron sputtering. The film chemical composition was investigated by energy-dispersive X-ray spectroscopy. X-ray irradiation was performed at different exposition times (30, 60 and 120 min) using wideband radiation of Cu-anode X-ray tube with approx 400 W of power applied (33 kV, 13 mA). Optical transmission spectra of Cu 6 PS 5 I-based thin films were studied using MDR-3 grating monochromator. Results . Optical transmission spectra of X-ray irradiated Cu 5.6 P 1.7 S 4.9 I 0.8 , Cu 6.4 P 1.1 S 4.6 I 0.9 and Cu 8.0 P 0.7 S 3.6 I 0.7 thin films were studied at various irradiation times at room temperature. With irradiation time increase the red shift of the short-wavelength part of transmission spectra and interference maxima is revealed. In the X-ray irradiated thin films the Uhrbach behavior of the optical absorption edge is observed. Optical absorption edge for X-ray irradiated thin films is shifted to the long-wavelength region with irradiation time increase. It leads to the energy pseudogap decrease and Uhrbach energy increase. Dispersion dependences of the refractive index for the X-ray irradiated thin films have shown a slight dispersion of the refractive indices in the transparency region, increasing with approaching the optical absorption edge. With irradiation time increase the nonlinear increase of the refractive indices in the X-ray irradiated thin films is revealed. Conclusions. The influence of X-ray irradiation on optical properties of Cu 6 PS 5 I-based thin films was studied. Changes in optical parameters of the thin films were investigated and described. With irradiation time increase the decrease of energy pseudogap as well as increase of Uhrbach energy and refractive index values was observed. It was determined that with irradiation time increase the darkening and densitification of the thin films occur. The increase of Uhrbach energy indicates on increase of structural disordering induced by the influence of X-ray irradiation.

In this paper the method of the density functional theory in the local electron density approximation with allowance for strong correlations in the d-shell of the noble metal ion (LDA+U method) calculations are performed of the band structure, the partial densities of electronic state and optical functions: dielectric permeability, refractive index, reflection and absorption coefficients of Ag7SiS5I crystal. According to the calculation results Ag7SiS5I is a indirect-gap semiconductor with the calculated energy of the band gap Egicalc=1.73eV. The analysis of partial contributions into the density of electronic states allowed to identify the genetic origin of different subbands of the valence band, and also to obtain the formation of a chemical bond in the crystal under study. The most important feature of the electronic spectrum of the Ag7SiS5I crystal is the presence of an intense peak in the density of states N(E) formed by Ag4d-like zone. The calculated spectral dependences of the absorption and reflection coefficients show the main features of the e2(ω) dependence, and the maxima of the energy distribution of the refractive index practically coincide in position with the centers of gravity of the bands of the real part of the complex permittivity.

The basic method of density functional theory (DFT) in the $\mathrm{LDA}+U$ -approximation has been used to calculate the band structure, full and partial densities of electronic states, spatial distribution of electron charge density and optical functions: dielectric permeability, refractive index, reflection and absorption coefficients of CU 7 SiS 5 I crystal. According to the calculation results CU 7 SiS 5 I is a direct-gap semiconductor with the calculated width of the band gap $E_{gd}^{calc}=2.34\ \mathrm{eV}$ , close to experimentally measured $E_{g}^{opt}=2.25\ \mathrm{eV}$

High-quality single crystals of Ag6+x(P1−xGex)S5I (0.25, 0.5, 0.75) solid solutions are grown from the solution–melt by vertical zone crystallization method. In order to study the crystal structure and to establish the mechanism of formation of Ag6+x(P1−xGex)S5I solid solutions as well as to explain the peculiarities of ion transport, the investigation of the single crystals was carried out using XRD analysis by the Rietveld method based on the refined models of initial Ag6PS5I and Ag7Ges5I structures. The measurements of electrical conductivity of single-crystal Ag6+x(P1−xGex)S5I samples was performed using impedance spectroscopy method in frequency range of 1 × 101–2 × 106 Hz and temperature interval of 293–383 K. Ionic and electronic components of electrical conductivity are determined using Nyquist plots. Based on the analysis of compositional dependences, it was found that for solid solutions the maximum of the ionic component of electrical conductivity and the minimum of its activation energy are observed. The features of the ion transport mechanism in Ag6+x(P1−xGex)S5I solid solutions with a heterovalent substitution are explained.

Impedance measurements of (Cu1−xAgx)7GeS5I mixed crystals are carried out in the frequency range from 10 Hz to 300 kHz and in the temperature interval 292–383 K. The temperature and frequency dependences of the electrical conductivity for (Cu1−xAgx)7GeS5I mixed crystals are studied. Based on the analysis of Nyquist plots and using the electrode equivalent circuits, the values of ionic and electronic components of the electrical conductivity are determined. The compositional behavior of the ionic and electronic conductivities, as well as the compositional behavior of their activation energies, are discussed. The ratio of ionic and electronic components of the conductivity for (Cu1−xAgx)7GeS5I mixed crystals was analyzed., На монокристалiчних зразках твердих розчинiв (Cu1−xAgx)7GeS5I були проведенi iмпеданснi вимiрювання у дiапазонi частот вiд 10 Гц до 300 кГц та в iнтервалi температур 292–383 K. Вивчено температурну i частотну залежностi електропровiдностi твердих розчинiв (Cu1−xAgx)7GeS5I. На основi аналiзу дiаграм Найквiста та з використанням електродних еквiвалентних схем були встановленi значення iонної та електронної компонент електропровiдностi. Дослiджено концентрацiйну поведiнку iонної та електронної провiдностi, а також концентрацiйну поведiнку вiдповiдних енергiй активацiй. Проаналiзовано спiввiдношення iонної та електронної компонент електропровiдностi для твердих розчинiв складу (Cu1−xAgx)7GeS5I.

The effect of two types of superionic nanoparticles, Cu7GeS5I and Ag7GeS5I, respectively on nematic liquid crystal (6CB) behavior under an external electric field is investigated. The response of both attenuation of surface acoustic waves propagating along with the substrate/liquid crystal interface and light transmission are used to study the structural changes induced by applied electric field. The increasing/decreasing regime as well as jumped change of applied field were used. The light transmission was investigated using linearly polarized laser beam (532 nm) propagating through the liquid crystal. Results obtained from both measurements for three different concentrations (0.01, 0.05 and 0.10 wt%) and in addition two different sizes of nanoparticles are compared and results, relying on structural changes, suspension stability and switching behavior are evaluated.

Cu7−xPS6−xIx mixed crystals were grown by the direct crystallization from a melt. The electrical conductivity is measured in the frequency range from 10 Hz to 300 kHz and in the temperature interval 293–383 K. The frequency, temperature, and compositional dependences of the electrical conductivity for Cu7−xPS6−xIx mixed crystals are studied. The measurements of thermoelectric parameters of Cu7−xPS6−xIx mixed crystals are carried out in the temperature interval 293–383 K. The compositional behaviors of the electrical conductivity, activation energy, Seebeck coefficient, and power factor are investigated. The interrelation between the structural, electrical, and thermoelectrical properties is analyzed., Методом спрямованої кристалiзацiї з розплаву вирощено монокристали твердих розчинiв Cu7−xPS6−xIx. Електрична провiднiсть вимiрювалася у частотному дiапазонi 10 Гц–300 кГц та в iнтервалi температур 293–383 K. Дослiджено концентрацiйну, частотну та температурну залежностi електричної провiдностi монокристалiв твердих розчинiв Cu7−xPS6−xIx. Вимiрювання термоелектричних параметрiв монокристалiв Cu7−xPS6−xIx проводились у температурному iнтервалi 293–383 K. Вивчено концентрацiйну поведiнку електричної провiдностi, енергiї активацiї, коефiцiєнта Зеєбека та термоелектричної потужностi. Проаналiзовано взаємозв’язок структурних, електричних та термоелектричних властивостей твердих розчинiв Cu7−xPS6−xIx.

Synthesis and growth of Cu7-xPS6-xBrx solid solutions were performed. Cu7-xPS6-xBrx solid solutions were grown by the method of direct crystallization from the melt. Impedance measurements were carried out in the range of frequencies from 10 Hz to 300 kHz and in the temperature interval 293–383 K. Temperature and frequency dependences of electrical conductivity for Cu7-xPS6-xBrx solid solutions were studied. Thermoelectric parameters of Cu7-xPS6-xBrx solid solutions were measured in the temperature interval 293–383 K. The compositional behavior of electrical conductivity and activation energy as well as Seebeck coefficient and power factor was analyzed. The influence of heterovalent substitution on structural, electrical and thermoelectric properties of Cu7-xPS6-xBrx solid solutions was studied.

Influence of Cu6PS5І nanoparticles on the dielectric properties of planarly oriented 6СВ liquid crystal (LC) is studied in the 10–106-Hz frequency range. Introduction of the nanoparticles is shown to result in an increase of the electric conductivity. Contrary to 6СНВТ LC, the conductivity monotonously depends on the nanoparticles’ concentration. The main reason of the much greater influence of Cu6PS5І nanoparticles on the 6СВ conductivity in comparison with 6СНВТ is related to a greater dissociation coefficient of Cu6PS5І in 6СВ than in 6СНВТ. This is confirmed by the fact that the dipole moment of the 6СВ molecules is greater than that of the 6СНВТ molecules.

(Ag 3 AsS 3 ) 0.9 (As 2 S 3 ) 0.1 thin films with high concentration of silver were deposited by a rapid thermal evaporation, their structural properties were studied using SEM and AFM. Roughness analysis of as-deposited films surfaces was performed. The influence of laser and e-beam irradiation on structural and optical properties was analysed. It is shown that e-beam, as well as laser illumination, causes a formation of flakes, bubbles on the surface of the films. Holographic gratings were recorded on the given films using green laser. Optical transmission kinetics with laser illumination shows its increase with illumination time.

Cu6PS5I-based thin films were deposited onto silicate glass substrates by non-reactive radio-frequency magnetron sputtering. The chemical composition of thin films was determined using energy-dispersive X-ray spectroscopy. Electrical conductivity of Cu6PS5I-based thin films was studied as dependent on chemical composition. Optical transmission spectra of Cu5.46P1.68S5.06I0.80 thin film were investigated within the temperature interval 77…300 K; temperature behaviour of optical absorption spectra and dispersion of the refractive index were also studied. Temperature dependences of the energy position of absorption edge, Urbach energy and refractive index of Cu5.46P1.68S5.06I0.80 thin film have been analyzed.

The ceramics based on (Cu0·5Ag0.5)7SiS5I solid solution of superionic conductor with argyrodite structure were prepared by using the powders with different particles size. The structural studies of powders were performed by XRD technique, while the ceramic samples with different average size of the crystallites were investigated by microstructural analysis. The total electrical conductivity of ceramic samples was measured by impedance spectroscopy in the frequency range from 10 Hz to 2 × 106 Hz and temperature interval from 292 K to 383 K. The contributions of ionic and electronic components into the total electrical conductivity were separated as well as their temperature behavior was studied. The dependences of ionic and electronic conductivity and their activation energies on average size of the crystallites in (Cu0·5Ag0.5)7SiS5I-based ceramic samples were investigated.

Thermal evaporation technique is used to deposite (Ga0,2In0,8)2Se3 thin films. The refractive index and extinction coefficient dispersions are obtained from the spectral ellipsometry measurements. The dispersion of the refractive index is described in the framework of the Wemple–Di Domenico model. The optical transmission spectra of a (Ga0,2In0,8)2Se3 thin film are studied in the temperature range 77–300 K. The temperature behavior of the Urbach absorption edge, as well as the temperature dependences of the energy pseudogap and Urbach energy, are investigated. The influence of different types of disordering on the optical absorption edge of a (Ga0,2In0,8)2Se3 thin film is discussed. Optical parameters of a (Ga0,2In0,8)2Se3thin film and a single crystal are compared., Тонкi плiвки (Ga0,2In0,8)2Se3 були отриманi методом термiчного напилення. За допомогою методики спектральної елiпсометрiї отримано дисперсiйнi залежностi показника заломлення та коефiцiєнта екстинкцiї. Дисперсiю показника заломлення описано в рамках моделi Уемпла–Дi Доменiко. Спектри оптичного пропускання тонкої плiвки (Ga0,2In0,8)2Se3 дослiджено в iнтервалi температур 77–300 К. Вивчено температурну поведiнку урбахiвського краю поглинання, а також температурнi залежностi ширини псевдозабороненої зони та урбахiвської енергiї. Обговорюється вплив рiзних типiв розупорядкування на край оптичного поглинання тонкої плiвки (Ga0,2In0,8)2Se3. Проведено порiвняння оптичних параметрiв тонкої плiвки та монокристала (Ga0,2In0,8)2Se3.

Synthesis and growth of (Cu1–xAgx)7GeSe5I mixed crystals were performed. Cu7GeSe5I and Ag7GeSe5I crystals were grown by the method of directed crystallization from the melt as well as (Cu1–xAgx)7GeSe5I mixed crystals were grown by zone crystallization from the melt. Electrical measurements were carried out in the frequency range from 20 Hz to 2 × 106 Hz and in the temperature interval 292–378 K. Temperature and frequency dependences of electrical conductivity for (Cu1–xAgx)7GeSe5I mixed crystals were studied. The compositional behavior of ionic and electronic conductivity as well as the compositional behavior of their activation energies are discussed. The ratio of ionic and electronic components of conductivity for (Cu1-xAgx)7GeSe5I mixed crystals was analyzed.

(Ag3AsS3)0.6(As2S3)0.4 thin films were deposited using rapid thermal evaporation (RTE) and pulse laser deposition (PLD) techniques. Ag-enriched micrometre-sized cones (RTE) and bubbles (PLD) were observed on the thin film surface. Optical transmission spectra of the thin films were studied in the temperature range 77–300 K. The Urbach behaviour of the optical absorption edge in the thin films due to strong electron–phonon interaction was observed, the main parameters of the Urbach absorption edge were determined. Temperature dependences of the energy position of the exponential absorption edge and the Urbach energy are well described in the Einstein model. Dispersion and temperature dependences of refractive indices were analysed; a non-linear increase of the refractive indices with temperature was revealed. Disordering processes in the thin films were studied and compared with bulk composites, the differences between the thin films prepared by RTE and PLD were analysed.

Cu 6 PS 5 I single crystals were grown using chemical vapor transport and Cu 6 PS 5 I micro- and nanocrystalline powders were prepared. Structural studies were performed using X-ray diffraction analysis and scanning electron microscopy. The influence of grain size on the phase transitions (PTs) and heat capacity in Cu 6 PS 5 I single crystals and micro- and nanocrystalline powders is studied in the temperature range 70–300 K. With average grain size reduction, the ferroelastic and superionic first-order PTs and the structural second-order PT shift towards higher temperatures. Besides, the anomaly at the second-order PT is fully smeared with average grain size reduction, while at high temperatures the new feature appears which is assigned to a “surface” PT.

Cu7PS6 crystals were grown using direct crystallisation from the melt (Bridgman–Stockbarger technique). The crystal structure of Cu7PS6 was determined by X-ray powder diffraction. Cu7PS6 crystallise in the cubic structure, space group P213 (No. 198), the lattice parameter a = 9.6706(1) Å, formula units per cell Z = 4. Electrical properties of Cu7PS6 crystals were studied in the frequency range 10–1010 Hz and in the temperature interval 296–351 K. The performed analysis shows that the Cu7PS6 crystals are mixed electron-ionic conductors with some growth defects.