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This work presents the results of microhardness investigations of single-crystal samples of Ag7+x(P1-xGex)S6 (x = 0, 0.1, 0.25, 0.33, 0.5, 0.75, 1) solid solutions. The dependences of microhardness H on load P and sample composition were investigated. The microhardness was found to decrease with applied load, which indicates presence of “normal” indentation size effect in Ag7+x(P1-xGex)S6 solid solutions. The obtained results were approximated in the framework of the geometrically necessary dislocations (Nix-Gao) model, and the model parameters were found. The effect of heterovalent Р5+ → Ge4+ substitution on the mechanical properties of Ag7+x(P1-xGex)S6 crystals was determined. [ABSTRACT FROM AUTHOR]

Herein we present the results of microhardness investigations aimed at monocrystalline samples of Ag7(Si1–xGex)S5I (0, 0.2, 0.4, 0.6, 0.8, 1) and Ag6+x(P1–xGex)S5I (0, 0.25, 0.5, 0.75, 1) solid solutions. The dependence of microhardness H on the load P and composition were investigated. It has been observed that the microhardness dependence on the applied load is characterized by a tendency to decrease with increasing the load. It indicates a presence of “normal” size effect in both Ag7(Si1–xGex)S5I and Ag6+x(P1–xGex)S5I (0, 0.25, 0.5, 0.75, 1) solid solutions. The revealed size effects of hardness in single crystals of Ag7(Si1–xGex)S5I and Ag6+x(P1-xGex)S5I solid solutions have been analyzed within the framework of the gradient theory of plasticity. The corresponding parameters of the model of geometrically necessary dislocations have been determined. [ABSTRACT FROM AUTHOR]

Samples of Ag7+x(P1-xGex)S6 (x = 0, 0.1, 0.25, 0.33, 0.5, 0.75, 1.0) solid solutions were obtained in the form of microcrystalline powders by grinding in an agate mortar. The diffuse reflectance spectra of the obtained Ag7+x(P1-xGex)S6 samples were studied in the spectral range 200 to 1400 nm at 293 K. The spectral dependences were analyzed using multilevel approximation by applying the Kubelka-Munk function and the Tauc method. It has been found that for Ag7+x(P1-xGex)S6 solid solutions, a red shift of the reflection edge beginning is observed with increasing the Ge content. The pseudo-gap values of Ag7+x(P1-xGex)S6 solid solutions was estimated by the Tauc method. It was found that the heterovalent cationic substitution P+5 → Ge+4 within the anionic sublattice leads to a monotonic nonlinear decrease in the pseudo-gap values. [ABSTRACT FROM AUTHOR]

Cu6PS5Br1-xClx mixed crystals were grown by chemical vapour transport. Optical absorption edge and optical polarization measurements were performed in the temperature range 77–320 K. The influence of anionic Br→Cl substitution on the phase transitions in Cu6PS5Br1-xClx mixed crystals is studied. Compositional dependence of the ferroelastic phase transition temperature for Cu6PS5Br1-xClx mixed crystals is obtained. The variation of optical parameters at ferroelastic phase transition is analyzed. [ABSTRACT FROM AUTHOR]

(Cu6PS5I)1–x(Cu7PS6)x mixed crystals were grown using the direct crystallization technique from melt (Bridgman–Stockbarger technique). The polymer composites based on (Cu6PS5I)1–x(Cu7PS6)x mixed crystals were prepared. Electrical properties of composites were studied in the frequency range from 10–3 Hz to 2·106 Hz at room temperature. The parallel equivalent circuit with double electric layer assumed at the electrode interface was applied to analyze the frequency dependences of electrical conductivity. It has been shown that the highest value of total electric conductivity is observed for the (Cu6PS5I)0.75(Cu7PS6)0.25-based composite. The further increase of Cu7PS6 content leads to the monotonically decreasing values of total electric conductivity. The ratio of total ionic to electronic components demonstrates the highest value for Cu6PS5I-based composite. [ABSTRACT FROM AUTHOR]

Polymer composites were prepared from (Ag1-xCux)7GeS5I mixed crystals grown using Bridgman-Stockbarger method. The impedance measurements were performed at room temperature in the frequency range 10-3-2.106 Hz. The frequency dependences of electrical conductivity and dielectric permittivity for composites based on (Ag1-xCux)7GeS5I mixed crystals were obtained. The Nyquist plots for (Ag1-xCux)7GeS5I-based composite has been analyzed. The influence of cation Ag→u substitution on electrical conductivity of composites based on (Ag1-xCux)7GeS5I mixed crystals has been studied. [ABSTRACT FROM AUTHOR]

(Ag3AsS3)0.6(As2S3)0.4 thin films deposited using the thermal evaporation technique onto glass substrates previously covered with layers of gold nanoparticles were studied. Optical transmission spectra of the sandwich structure were studied within the temperature range 77...300 K. The absorption spectra in the region of its exponential behaviour were analyzed, the dispersion dependences of refractive index as well as the temperature dependences of the energy pseudogap and Urbach energy were investigated. The disordering processes in the sandwich structure were discussed. The comparative analyses of optical parameters in single (Ag3AsS3)0.6(As2S3)0.4 layer and in the sandwich structure were performed. [ABSTRACT FROM AUTHOR]

Cu6PS5I-based thin films are deposited onto silicate-glass substrates using magnetron sputtering. Their chemical compositions are determined with the aid of energy-dispersive X-ray spectroscopy. Changes in the Raman spectra of the Cu6PS5I-based thin films with respect to the spectra typical for crystalline Cu6PS5I are discussed. Optical absorption spectra and refractive indices for the films with different Cu contents are studied. Decrease in the energy pseudogap and the Urbach energy is observed with increasing Cu content, accompanied by increase in the refractive index. Electrical conductivity of the Cu6PS5I-based thin films is revealed to increase nonlinearly with increasing copper concentration. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The influence of Cu7PS6 nanoparticles with the average size 117 nm on the dielectric properties of planar oriented nematic liquid crystal 6CB has been investigated within the frequency range 10¹...106 Hz and at the temperature 293 K. It has been shown that when changing the concentration of nanoparticles within the range 0 to 1 wt.%, the conductivity of the liquid crystal changes stronger than its dielectric permittivity. It has been shown that the electrical conductivity increases monotonously with increasing the concentration of nanoparticles. However, for this dependence a saturation effect is observed. The mechanism of this effect was proposed. [ABSTRACT FROM AUTHOR]

Mixed (Cu6PS5I)1-x(Cu7PS6)x crystals were grown using a direct crystallization technique. Being based on the X-ray diffraction data, their crystal structure was studied, showing face-centred cubic lattice for Cu6PS5I-rich solid solutions (x < 0.12) and primitive cubic lattice for Cu7PS6-rich (0.84 < x < 1) solid solutions. These structural data correlate with the Raman spectra where, besides the common features typical for the argyrodite-type Cu6PS5I and Cu7PS6 crystals, weaker bands characteristic only for the end-point compounds are revealed in the corresponding compositional intervals. [ABSTRACT FROM AUTHOR]

Cu6PS5I-based thin films were deposited using non-reactive radio-frequency magnetron sputtering. Structural studies of thin films were performed by scanning electron microscopy, their chemical composition were determined using energydispersive X-ray spectroscopy. As-deposited thin films were irradiated with wideband radiation of Cu-anode X-ray tube at different exposition times. Optical transmission spectra of X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films were measured depending on irradiation time. The Urbach absorption edge and dispersion of refractive index for X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films were studied. It has been revealed the nonlinear decrease of energy pseudogap and nonlinear increase of refractive index with increase of X-ray irradiation time. [ABSTRACT FROM AUTHOR]

Cu5.5P1.2Se5.0I1.3 thin film was deposited onto silicate glass substrate by nonreactive radio frequency magnetron sputtering. Structural studies were carried out using X-ray diffraction and SEM techniques. Spectrometric studies of transmission spectra of Cu5.5P1.2Se5.0I1.3 thin film in the temperature interval 77 to 300 K were investigated. It is shown that the temperature behaviour of optical absorption edge is described by the Urbach rule. Temperature dependences of optical parameters of the Urbach absorption edge and refractive index have been analyzed. The influence of temperature and structural disordering on the Urbach tail has been studied. The comparison of optical parameters of Cu6PSe5I crystal and Cu5.5P1.2Se5.0I1.3 thin film has been performed. [ABSTRACT FROM AUTHOR]

(Ag3AsS3)x(As2S3)1-x (x = 0.3; 0.6; 0.9) thin films were deposited onto a silica substrate by rapid thermal evaporation. The amount of Ag-rich crystalline phase precipitates on the surfaces of the films increases with Ag3AsS3 content. It has been shown that the absorption edge spectra are described by the Urbach rule. The temperature behaviour of absorption spectra was studied, the temperature dependences of energy position of absorption edge and Urbach energy were also investigated. The influence of compositional disordering due to Ag3AsS3 introduction into As2S3 on the optical parameters of (Ag3AsS3)x(As2S3)1-x thin films were analyzsed. The spectral, temperature and compositional behaviour of refractive index for (Ag3AsS3)x(As2S3)1-x thin films were studied. [ABSTRACT FROM AUTHOR]

Cu6.35P1.77S4.72Br0.15 thin film was obtained using the high target utilization sputtering onto c-cut sapphire substrates. X-ray diffraction studies show the film to be amorphous with some crystalline inclusions. SEM investigations indicate formation of periodical “forest-like” quasi-two-dimensional pillared structure. Electrical conductivity of Cu6.35P1.77S4.72Br0.15 thin film was measured in the temperature interval 4.5…300 K, three regions with different activation energy were revealed. Optical constants were obtained using the technique of spectroscopic ellipsometry and used for calculation of optical absorption spectrum. Optical absorption edge has an exponential form, the Urbach energy shows the significant disordering in Cu6.35P1.77S4.72Br0.15 thin film. [ABSTRACT FROM AUTHOR]

Cu7GeS5I thin films were obtained by non-reactive radio frequency magnetron sputtering onto silicate glass substrates. Optical transmission spectra of as-deposited and annealed Cu7GeS5I thin films were measured in the temperature interval 77-300 K. The temperature behaviour of Urbach absorption edge and dispersion of refractive index for as-deposited and annealed Cu7GeS5I thin films was analyzed. Influence of annealing on the optical parameters and disordering processes in Cu7GeS5I thin films was studied. [ABSTRACT FROM AUTHOR]

Cu6PS5I-based thin films were deposited onto silicate glass substrates by nonreactive 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. [ABSTRACT FROM AUTHOR]

(Ag3AsS3)0.6(As2S3)0.4 thin films were deposited onto a silica substrate by using rapid thermal evaporation. The surfaces of the films were covered with Ag-rich crystalline micrometer-sized cones. The optical transmission spectra of thin films were studied within the temperature range 77...300 K. The absorption spectra in the region of its exponential behaviour were analysed, the dispersion dependences of refractive index as well as the temperature dependences of energy position of absorption edge and Urbach energy were investigated. [ABSTRACT FROM AUTHOR]

Cu6(P1-xAsx)S5I mixed crystals were grown using chemical vapour transport. Temperature isoabsorption investigations of optical absorption edge enable to reveal anomalies typical for the first- and second-order phase transitions as well as to construct the x, T-diagram. The spectrometric measurements of the optical absorption edge in Cu6 (P1-xAsx)S5I superionic mixed crystals were carried out within the temperature range 77-320 K. The influence of temperature and composition on optical absorption edge, parameters of exciton-phonon interaction as well as ordering-disordering processes in Cu6 (P1-xAsx)S5I superionic mixed crystals have been studied. [ABSTRACT FROM AUTHOR]

Implantation of Cu6PS5X (X = I, Br) single crystals was carried out for different values of fluence with using P+ ions; the energy of ions was 150 keV. For the implanted Cu6PS5X crystals, the structural studies were performed using the scanning electron microscopy technique and energy-dispersive X-ray spectroscopy. Spectrometric studies of optical absorption edge and luminescence were carried out within the temperature range 77…320 K. The influence of ionic implantation on luminescence spectra, parameters of Urbach absorption edge, parameters of exciton-phonon interaction as well as ordering-disordering processes in Cu6PS5X (X = I, Br) superionic conductors have been studied. [ABSTRACT FROM AUTHOR]