Electrical conductivity of “liquid crystal – Cu6PS5I superionic nanoparticles” composites

One of the promising methods to extend the liquid crystal (LC) functionality is introduction of the nanoparticles. Thus, nanoparticles of superionic conductors with argyrodyte structure, in particular Cu6PS5I, can help to extend functional properties of LC. They are characterized by high electrical conductivity as well as ferroelastic and nonlinear optical properties. Therefore, the aim of this work was to study the influence of Cu6PS5I nanoparticles on the electrical conductivity of 6СВ and 6СНВТ liquid crystals

Electrical conductivity of “liquid crystal – Cu6PS5I superionic nanoparticles” composites

One of the promising methods to extend the liquid crystal (LC) functionality is introduction of the nanoparticles. Thus, nanoparticles of superionic conductors with argyrodyte structure, in particular Cu6PS5I, can help to extend functional properties of LC. They are characterized by high electrical conductivity as well as ferroelastic and nonlinear optical properties. Therefore, the aim of this work was to study the influence of Cu6PS5I nanoparticles on the electrical conductivity of 6СВ and 6СНВТ liquid crystals

Optical properties of sandwich structure "(Ag[3]AsS[3])[0.6](As[2]S[3])[0.4] thin films - gold nanoparticles" prepared by pulse laser deposition

Among silver-containing chalcogenides Ag-As-S ternary system are take the remarkable place. Glasses and composites of Ag–As–S system are promising materials for creation of solid electrolytes, electrochemical sensors, electrochromic displays etc. In the recent years surface plasmon resonance has been used to enhance photostructural changes due to the laser light. Therefore, it was of a certain interest to obtain and examine such effects in the new investigated Ag-As-S thin films

Optical properties of sandwich structure "(Ag[3]AsS[3])[0.6](As[2]S[3])[0.4] thin films - gold nanoparticles" prepared by pulse laser deposition

Among silver-containing chalcogenides Ag-As-S ternary system are take the remarkable place. Glasses and composites of Ag–As–S system are promising materials for creation of solid electrolytes, electrochemical sensors, electrochromic displays etc. In the recent years surface plasmon resonance has been used to enhance photostructural changes due to the laser light. Therefore, it was of a certain interest to obtain and examine such effects in the new investigated Ag-As-S thin films

Phonon spectra of Cu₆PS₅Br superionic ferroelastic: experimental and theoretical studies

The anomalous temperature behavior of the Raman scattering bands at superionic phase transition of Cu₆PS₅Br is revealed. Using density functional perturbation theory within local density approximation, ab initio long-wavelength phonons have been obtained for high-symmetry cubic structure. In the calculated phonon spectrum two unstable modes indicate the experimentally observed sequence of ferroelastic and superionic phase transitions.Експериментально виявлено аномальну температурну поведiнку пiкiв раманiвського розсіювання свiтла при суперiонному фазовому переходi в Cu₆PS₅Br. Для високосиметричної кубiчної фази теоретично розраховано першопринципнi частоти довгохвильових фононiв з використанням теорії збурень функцiонала густини у локальному наближеннi. У фононному спектрi спостерiгаються дві нестабiльнi моди, якi вказують на експериментально спостережувану послiдовнiсть сегнетоеластичного i суперiонного фазових переходiв

Structural, electrical and optical investigations of Cu₆PS₅Br-based thin film deposited by HiTUS technique

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

The non-linear dependence of 6СНВТ liquid crystal conductivity on the concentration of gold nanoparticles

Within the frequency range 10⁻¹…10⁶ Hz at the temperature 293 K, the effect of gold nanoparticles on the dielectric properties of the planar-oriented nematic liquid crystal 6СНВТ has been studied. The concentration of nanoparticles with the average diameter 3 to 5 nm was chosen as 0.01, 0.02 and 0.1 wt.%. It has been shown that for the frequencies less than 10 Hz, the dielectric properties of the samples can be described with the Debye dispersion. For the samples with the concentration of gold nanoparticles 0.1 wt.%, the time of relaxation has been estimated (4.7±0.5 s). It has been also shown that the conductivity of the liquid crystal depends non-linearly on the concentration of nanoparticles introduced into the liquid crystal. The greatest change in conductivity of the liquid crystal on the concentration of introduced gold nanoparticles has been obtained within the range of 0.01 to 0.02 wt.%. It has been assumed that the conductivity of 6СНВТ that depends non-linearly on the concentration of introduced gold nanoparticles is caused by the competing processes of ion desorption from the gold nanoparticles and of nanoparticle aggregation

Raman scattering studies of composites based on Cu₆PS₅X (X = I, Br) superionic nanocrystals

Composites were prepared by mixing Cu₆PS₅X (X = I, Br) nanocrystalline powders obtained by ball milling with different polymers. The average nanocrystal size was estimated from X-ray diffraction; the composites were studied by scanning electron microscopy. Phonon spectra of nanocomposites with different polymer matrices, size and concentration of nanocrystals were studied using Raman spectroscopy. It has been revealed that the surface-to-bulk phonon integrated intensity ratio strongly varies with the type of polymer matrix, average grain size and concentration of nanocrystal

Influence of cation substitution on phase transition and optical absorption edge in Cu₆(P₁₋xAsx)S₅I mixed crystals

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)S₅Isuperionic mixed crystals have been studied

Influence of cation substitution on electrical conductivity and optical absorption edge in Cu₇(Ge1–xSix)S₅I mixed crystals

Electrical conductivity of Cu₇(Ge₁₋xSix)S₅I mixed crystals was measured in the frequency range 1.0x10⁶ –1.2x10⁹ Hz and in the temperature interval 100–300 K. The frequency and temperature behaviour of the electrical conductivity were analyzed. The optical absorption edge of Cu₇(Ge₁₋xSix)S₅I mixed crystals within the temperature range 77–300 K was studied. The compositional dependences of the electrical conductivity, activation energy, optical pseudogap and Urbach energy were obtained. The influence of Ge→Si cation substitution on the optical absorption processes in the Cu₇(Ge₁₋xSix)S₅I mixed crystals is investigated