A Ca8CdLa(PO4)(7) phase was prepared by a high-temperature solid-state reaction in air. The bulk and local cation composition was determined by inductively coupled plasma atomic emission spectroscopy and by energy-dispersive X-ray spectrometry. Second-harmonic generation, differential scanning calorimetry and dielectric measurements revealed the presence of a reversible ferroelectric first-order phase transition from a ferroelectric beta-phase (space group (SG) R3c) to a paraelectric beta '-phase (SG R (3) over barc). The phase transition temperature, T-c, is 865 +/- 10 K. The beta-Ca-3(PO4)(2) (beta-TCP) related structure was refined by the Rietveld method in the SG R3c using powder synchrotron X-ray diffraction data. The distribution of Ca2+, Cd2+ and La3+ cations among the sites of the beta-TCP-type structure was found. According to crystal structure refinement, M5O6 octahedra are occupied by Ca2+ and Cd2+ (M5 = 0.307(6)Ca2+ + 0.693(6)Cd2+) while Ca2+ and La3+ cations occupy M1 and M3 sites of the beta-TCP-type structure. Analysis of the difference electron density map [rho dif: (x; y; z)] revealed the presence of small residual electron density at the M4 site. The M4 position is partially occupied by Ca2(+) cations (M4 = 0.131(6)Ca2+). The elemental composition after the Rietveld refinement is determined as Ca8.61Cd0.70La(0.82)(PO4)(7). Conductivity measurements revealed that the calculated sigma(bul)k (sigma(bulk) = 4.01 x 10(-6) S cm(-1) at 900 K and sigma bulk = 1.49 x 10(-4) S cm(-1) at 1270 K) for Ca8.61Cd0.70La0.82(PO4)(7) was lower than one for other beta-TCP-type compounds.

Works performed at the A. V. Shubnikov Institute of Crystallography on the development of UV range optical filters based on complex compounds of nickel and cobalt are reviewed. The structural relationships of the crystal optical properties and their thermal stability are considered. Fundamental features of mixed crystals grown from solution and advanced approaches to creating optical filters based on structurally perfect mixed crystals K2(Co, Ni)(SO4)2 · 6H2O are described. The possibility of creating UV-A optical filters by partial substitution of the ligand environment of transition metal ions is demonstrated.

The problem of high plasticity and fluidity of phases of acidic salts with high proton conductivity of such superproton crystals of the MmHn(AO4)(m + n)/2 · yH2O (где M = NH4, K, Rb, Cs; А = P, As, S, Se). Various methods are chosen for obtaining composite materials based on the proton conductor Cs6(SO4)3(H3PO4)4 with the formation of a three-dimensional reinforcing fabric by the volume of the material present. For the first time, the temperature dependences of the hardness and elasticity of polycrystalline Cs6(SO4)3(H3PO4)4 pressed into a pellet were measured before and after the transition to the superproton state. Composite materials with the compositions xCs6(SO4)3(H3PO4)4(1– x)teflon and xCs6(SO4)3(H3PO4)4(1 – x)[SiOR]n (where 0.95 ≥ x ≥ 0.5 wt. %). The method of X-ray phase analysis on consumption dependency Taking into account the raster electronic assessment of the calculation of income phases in the income of composite materials. It is shown that with the proportion of the reinforcing component, the conductive phase is enveloped. Conductivity of composite materials research by impedance spectroscopy.

In this study, an approach for the facile and versatile synthesis of multicomponent superionic nanofluorides is proposed. The results of synthesis optimization of the tysonite-type LaF3 and La0.95Sr0.05F2.95 (sp. gr. P (3) over bar c1) nanopowders with a particle size up to 100 nm by the trifluoroacetate precursors thermal decomposition under various conditions (dynamic vacuum and ambient atmosphere) are presented. The produced samples are characterized by X-ray diffraction, electron microscopy, and differential scanning calorimetry. Decarbonization annealing of the initial nanopowders in air at 773 K is urgent for the effective elimination of amorphous carbon formed as a result of the metal-organic precursors decomposition. The nanoceramics were pressed to a theoretical density of 75-80 % and their ion-conducting properties were measured using impedance spectroscopy. The conductivity of decarbonized La0.95Sr0.05F2.95 composition, obtained in a dynamic vacuum, is 1 x 10(-3) S/cm at 500 K, which exceeds the performance of undoped LaF3 ceramics by approximately 60 times. The conductive properties of nanoceramics, produced from decarbonized vacuum-synthesized powders, are 5 times higher (1 x 10(-3) Sm/cm) compared to mechanochemically fabricated ones. Air-synthesized (773 K) La0.95Sr0.05F2.95 ceramics are conducted significantly worse, although no traces of pyrohydrolysis were detected. Thus, the precursors thermal decomposition method opens up great prospects for the advanced production of ion-conducting nanomaterials based on multicomponent fluoride compounds for solid electrolyte design.

The work presents the results of comprehensive studies of the optical and transport properties, phase transition heats, the X-Ray diffraction and Raman spectra of Ge2Sb2Se4Te1, Sb2Se3 and Bi2Se3 samples obtained by vacuum thermal deposition. We demonstrate a high contrast in the refractive index and extinction coefficient in the spectral range in wavelengths of 500-1800 nm and transmissivity and reflectivity spectra in the range in wavelengths of 500-3000 nm. The investigated materials show low optical losses and high figure of merit in much of the IR-spectrum. Changes in structural properties are analyzed by XRD and Raman methods. Features of phase transformations are described by thermogravimetry and differential scanning calorimetry.

In this work, a doping strategy was used to achieve a good conductivity in samarium zirconate which crystallizes in the pyrochlore. The production of nanopowders made it possible to form high-density ceramics with an optimal microstructure. It is shown that intrinsic and impurity defects coexist in Sm2-xCaxZr2O7-delta, impairing ion transport at high doping levels. Despite this, Sm(1.95)Ca(0.05)Zr(2)O(7-delta )maintains low activation energy of the parent and has good ionic conductivity (10(-3) S center dot cm(-1) at 600 degree celsius) which is one of the largest among oxide pyrochlores. It has been shown to have a good chemical stability. The material has a thermal expansion coefficient (TEC) of 12 ppm K-1 which is higher than YSZ and provides better compatibility with electrode materials. The above makes it possible to successfully use it as a highly stable oxygen electrolyte or an intermediate thin layer at the electrolyte-electrode interface in electrochemical devices.

The dynamics of the phase transition (PT) in triglycine sulfate crystals, either nominally pure or doped in different ways (upon homogeneous and profiled impurity introduction into the crystal) with chrome impurity (Сr 3+ ), has been studied by analyzing the dielectric spectra measured in the ranges of frequencies 1–10 7 Hz and temperatures 23–60°C upon heating and cooling. It is shown that the introduction of impurity shifts the PT temperature range both upon heating and cooling. The PT temperature dynamics is found to depend both on the presence of impurity and on the way of its introduction into the crystal. The dependence of the width of the PT temperature range on the frequency at which the dielectric spectra were measured was shown to increase directly proportion to frequency.

A series of solid acid compounds, representing the large family MmHn(AO4)(m + n)/2·yH2O (where M = K, Rb, Cs, NH4; AO4 = SO4, SeO4, HPO4, HAsO4), is characterized by high values of own proton conductivity, which arises as a result of a phase transition through the formation of a dynamically disordered hydrogen bond network. Such superprotonic phase transitions are observed, however, not for all compounds of the family and Rb3H(SO4)2 is one of them. The occurrence of superprotonic phase transitions has been experimentally demonstrated in the (KxRb1−x)3H(SO4)2 solid solutions through cation substitution. The high-temperature phases are unstable towards decomposition reaction, and their temperature range of existence is about 1–7 °C. The implementation of superprotonic transitions is discussed in terms of hydrogen bond lengths.

An optimized scalable production of single-phase rare-earth doped β-NaYF 4 nanoparticles is developed by the high-energy ball milling. This approach opens up prospects for the photoluminescent nanomaterials fabrication for biotechnology and photonics.

Nanopowders of tysonite solid solutions La 1 − x Ba x F 3 − x ( х = 0–0.07) are synthesized for the first time through the thermal decomposition of lanthanum and barium trifluoroacetates. Samples are characterized via electron microscopy, X-ray phase analysis, and impedance spectroscopy. Nanoparticles are found to be crystalline and have characteristic sizes of 20–75 nm. The ionic conductivity of solid solutions up to 300°C is determined by surface phenomena at the particle boundaries.

KR3F10 (R = Ho, Er; sp. gr. ) crystals have been grown by the vertical directional crystallization. The incongruent melting of these compounds is experimentally established, and the temperatures of the corresponding thermal effects are determined. Narrow regions of homogeneity are found for the studied crystals; these regions are also characteristic of the entire series of KR3F10 crystals under study. The cubic lattice parameter monotonically decreases along the crystal length and varies in the range of 11.5782(2)–11.5654(5) Å for KHo3F10 and 11.5225(1)–11.5102(4) Å for KEr3F10. The conditions for growing KR3F10 crystals of optical quality from melt are optimized.

The solubility of tetracene crystals has been investigated experimentally and theoretically within the approximation of regular-solution model. The grown crystals had a shape of thin elongated plates. The largest tetracene crystal (8 mm × 50 μm in size) was grown from a benzene solution by precipitant vapor diffusion into solution. The X-ray diffraction pattern from a developed crystal face is the result of the X-ray beam reflection from the (001) plane of a set of monolayers with a thickness d001 = 1.21 nm. An analysis of the surface morphology of the (001) face of tetracene crystal by atomic force microscopy (AFM) revealed the presence of elementary growth steps, whose height coincides (within the measurement error) with the monolayer thickness d001. The parameters of melting (Tm = 343.0°C, ΔHm = 35.6 kJ/mol) and polymorphic transition (Ttr =310.0°C, ΔHtr = 0.9 kJ/mol) of tetracene were refined using differential scanning calorimetry (DSC). A comparison of the optical absorption and luminescence spectra of solutions of a pure tetracene sample and a processed (previously molten in a hermetic crucible in an inert atmosphere) sample in toluene confirms degradation of the material subjected to overheating above the melting temperature.

The process of spray drying synthesis of the charge compositions based on silicon nitride α-Si3N4 with organic compounds of aluminum and yttrium in the molar ratio of 3:5 (stoichiometry of yttrium-aluminum garnet) as the sintering additive is considered. The sintered compositions 91.5 % wt. Si3N4 + 8.5 % wt. additive (in terms of garnet) were investigated by X-ray diffraction analysis and scanning electron microscopy as well as by the methods of thermal analysis. The charge compositions were annealed in four stages up to a temperature of 1000℃ in order to decompose organics and form the oxide phase of the sintering additive. High-speed (100 °C/min) spark plasma sintering (SPS) technology was used to produce 10 mm ceramic samples in vacuum, under uniaxial pressure of 70 MPa. The microstructure, mechanical properties and phase composition of ceramics were investigated. Influence of preliminary annealing of charge compositions on structure, phase composition and physical-mechanical properties of ceramics were studied. It is established that preliminary multistage annealing of charge compositions influences the SPS kinetics as well as the density and phase composition of the ceramic. It has been established that the kinetics of SPS of the pre-annealed powders has two-stage character of the shrinkage. In this case denser ceramic microstructure is formed than in the case of reaction synthesis of sintering additive (for charge composition without pre annealing) during the SPS, but pre annealing slows down the growth of elongated β-Si3N4 grains and the volume of sintering additive phase increases. It is shown that in the case of sintering ceramics from unannealed charge compositions the material has lower density but higher hardness. Based on the Yang-Kutler model, the activation energy of the SPS process is determined and it is shown that the compaction kinetics of Si3N4 with sintering additive powders is determined by the intensity of viscous flow of the oxide phase on the grain boundaries of ceramics.

Nanopowders of tysonite solid solutions La1 – xBaxF3 – x (х = 0–0.07) were synthesized for the first time by thermal decomposition of lanthanum and barium trifluoroacetates. The samples obtained were characterized by electron microscopy, X-ray phase analysis, and impedance spectroscopy. Nanoparticles are crystalline and have characteristic sizes of 20–75 nm. The ionic conductivity of solid solutions in the range up to 300°C is determined by surface phenomena at the particle boundaries.

In this work, we present results on the growth of centimeter-scale pentacene crystals using the physical vapor transport method in a dual-temperature zone horizontal furnace. It was established that intensive crystal growth processes occurred in transition regions with sudden temperature changes, while crystal growth was practically not observed in regions with slightly varying temperatures. During crystal growth, co-precipitating golden needle-like crystals reaching lengths of more than 10 mm were obtained. Using the method of single-crystal X-ray diffraction at 85 and 293 K for dark-blue lamellar pentacene crystals, the crystal structure was refined in a triclinic system with sp.gr. P1¯. It was established that the golden needle crystals consisted of molecules of the pentacene derivative—5,14-pentacenedione, the crystal structure of which was solved for the first time in a rhombic system with sp.gr. P212121. The absorption and luminescence spectra of pentacene and 5,14-pentacenedione in toluene solutions were obtained and analyzed. The electrical properties of the prepared pentacene thin films and single crystals grown under physical vapor transport conditions were evaluated by fabricating and characterizing field-effect transistors (FETs). It was shown that the presence of impurities in the commercial pentacene material had a significant effect on the morphological quality of thin polycrystalline films and noticeably reduced the hole mobility.

In this paper, the conditions of phase formation in the system CsOH–H2SO4–H3PO4–H2O are considered for the first time. The phase formation of Cs6(SO4)3(H3PO4)4 at t = 50 °C has been studied extensively. The main concentration boundary conditions for this compound are considered for the first time. The solubility congruence of Cs6(SO4)3(H3PO4)4 is shown. Conditions and approaches for obtaining crystals by isothermal evaporation and saturated solution temperature reduction methods are considered. The results of obtaining Cs6(SO4)3(H3PO4)4 crystals with maximum dimensions of ~20 mm are presented.

Thermal properties of iron oxide nanoparticles (IONPs) stabilized with starch, 5-sulfosalicylic acid (SA) and oleic acid (OA) were studied in the range 30-1000 degrees C by thermogravimetry and differential thermal analysis in oxidizing atmosphere. Synchronized mass spectrometry data was collected. The sizes and morphology of IONPs were determined with transmission and scanning electron microscopy analyses. Three stages of thermal transformation were revealed: (I) water desorption, (II) organic content pyrolysis and (III) iron oxide phase transition. The thermal stability of the organic part was analyzed. Thermal conversions of modified IONPs were compared with the data for uncoated magnetite.

The phase equilibria in the K 2 SO 4 –Rb 2 SO 4 –H 2 SO 4 –H 2 O system have been investigated under isothermal conditions at 25°C. The concentration limits of crystallization of solid solutions with the general formulas (K x Rb 1– x ) 2 SO 4 , (K x Rb 1– x ) 3 H(SO 4 ) 2 , (K x Rb 1– x ) 9 H 7 (SO 4 ) 8 ⋅ H 2 O, and K x Rb 1– x HSO 4 and the K 0.55 Rb 0.45 HSO 4 phases are determined. The dependences of the equilibria of saturated solutions on the initial production conditions are revealed. The growth conditions for large single crystals of complex acid potassium–rubidium sulfates are determined. The phase-equilibrium diagram of the system is constructed.

The phase equilibria in the K2SO4–Rb2SO4–H2SO4–H2O system have been investigated under isothermal conditions at 25°C. The concentration limits of crystallization of solid solutions with the general formulas (KxRb1–x)2SO4, (KxRb1–x)3H(SO4)2, (KxRb1–x)9H7(SO4)8 ⋅ H2O, and KxRb1–xHSO4 and the K0.55Rb0.45HSO4 phases are determined. The dependences of the equilibria of saturated solutions on the initial production conditions are revealed. The growth conditions for large single crystals of complex acid potassium–rubidium sulfates are determined. The phase-equilibrium diagram of the system is constructed.

In isothermal conditions (25 ?C) phase equilibria are researched in the (NH4)2SO(4) - Rb2SO4 - H2SO4 - H2O system. Concentration limits of the solid solutions crystallization with general formulas of ((NH4)(x)Rb1 -x)(2)SO4, ((NH4)(x)Rb1 -x)(3)H(SO4)(2) and (NH4)(x)Rb1 -xHSO4 are determined. Conditions of obtaining massive single crystals of ammonium and rubidium complex acid sulfates are determined.