ISSN (print): 1087-6596, ISSN (online): 1608-313X Editor-in-Chief: Vladimir Ya. Shevchenko Publisher: Pleiades Publishing Indexed in: RUS White List (level 2), Scopus, Web of Science (SCIE)
Modeling Self-Organization Processes in Crystal-Forming Systems: Suprapolyedic Na18Hg157 Precursor Clusters for the Self-Assembly of the Na99Hg468–hP567 Crystal Structure
Using computer methods (the ToposPro software package), the combinatorial-topological analysis and modeling of the self-assembly of the Na99Hg468–hP567 crystal structure are carried out with the following parameters of the hexagonal cell: a = b = 39.703 Å, c = 9.681 Å, V = 13216 Å3, space group P-6, and 132 crystallographically independent atoms. Three supracluster precursors K175-A, K175-B, and K175-C composed of Na18Hg157 are identified in the form of three connected gear rings of Na-polyhedra with symmetry g = –6. The symmetry and topological code for the self-assembly of the 3D structures from the precursor nanoclusters is reconstructed. In the [001] direction, the K175 supracluster precursors are linked by Hg6 gear rings and Na spacers to form columns. In the columns, the distance between supraclusters K175 determines the value of the translational vector modulus c = 9.681 Å. When a skeleton is formed in the local environment of a column of K175-C supraclusters (centered at a height of z = 0), six columns of alternating K175-A and K175-B supraclusters are located with an offset of 1/2 in the [001] direction. The distance between equivalent columns from K175 clusters corresponds to the value of the translation vector modules a and b.
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Modeling Self-Organization Processes in Crystal-Forming Systems: New Two-Layer Cluster–Precursor K44 = 0@8(Na2In6)@36(In6Cd6K6)2 for the Self-Assembly of the K23Na8Cd12In48–hP91 Crystal Structure
Using computer methods (the ToposPro software package), the combinatorial-topological analysis and modeling of the self-assembly of the K23Na8Cd12In48–hP91(a = b = 17.114 Å, c = 10.442 Å, group P6/mmm) crystal structure are carried out. The chemically different precursor clusters 0@8(Na2In6) and 0@K2In6 in the form of hexagonal bipyramids are established. The centers of Na2In6 clusters occupy positions 1a with a symmetry of 6/mmm. The centers of the K2In6–A and K2In6–B clusters occupy positions 2c with symmetry –6m2, and 3g positions with mmm symmetry. The Na2In6 clusters are the templates on the surface of which atomic shells of 36 atoms are formed. The composition of the two-layer cluster is K44 = 0@8(Na2In6)@36(In6Cd6K6)2. Layer formation occurs upon the K44 clusters binding to the K2Cd6–A clusters. The symmetry and topological code of the self-assembly of the 3D structures from the K44 suprapolyhedral precursors with the participation of the K2Cd6 polyhedral clusters, as well as Na and K spacer atoms, are reconstructed.
Synthesis of a New Class of Materials with a Regular (Periodic) Interconnected Microstructure
The fundamental principles for the synthesis of a new class of materials with a controlled (periodic) interconnected structure based on triply periodic minimal surfaces are formulated. The chemical synthesis based on the reaction-diffusion Turing reaction, which enables us to fabricate periodic microstructures, is analyzed.
Investigation of Hydrolytic Polycondensation in Systems Based on Tetraethoxysilane by DK-Spectrophotometry Method
The research of the hydrolytic polycondensation kinetics of tetraethoxysilane (TEOS) is required in order to understand the sol-gel synthesis processes and identify the factors determining the direction of these processes. An extensive analysis of these problems permits us to predict appropriate ways for the synthesis of new substances with the predetermined properties. Studying the kinetics of the polycondensation of TEOS above the gel point will allow solving problems of the gels’ strength and the gels’ degree of structuring and thus optimizing the conditions of the further processing materials for the production of the final synthesis products. In this paper the results of the research on the structuring kinetics of the silica in the modeled aqueous-alcoholic solutions of TEOS, including boron-containing solutions, before and after the gel point at various molar ratios of H2O : SiO2 and pH values of 2.0 and 6.0 by the differential kinetic spectrophotometry are presented. The kinetic scheme developed by the authors and the mathematical tool allow determining the degree of the direction of the process of silica polycondensation. The data obtained on the model systems were applied to the description of the silica structuring process in the acid solutions resulting from the treatment of the single-phased sodium borosilicate glass. The obtained results will form the base for the interpretation of the experimental data on the kinetics of the silica structuring contained in the unstable phase of the two-phased alkali-borosilicate glass during the leaching process; i.e., it will allow predicting the dissolution rate, forms of existance, gelation time, strata formation time and, as a consequence, the formation of some porous structure of the resulting porous glass.
Mass Spectrometry of Chalcogenide Glass and Carbon Nitrides
Based on the mass spectrometric study of chalcogenide and fullerene-chalcogenide glass (CG), as well as amorphous and crystalline carbon nitrides with general formula CnNm, which are similar to CG, are considered according to the type of chemical bond, their vapor composition, and the effect of the initial specimens of the synthesized materials, including those containing metal components, fullerenes, and binary and ternary chemical compounds, as well as other structural units (SUs) and structural motifs.
Optical and Dielectric Properties of Nanocomposites Based on Zinc and Tin Oxides in Nanoporous Glass
The spectra of the optical density and luminescence and dielectric spectra of crystalline nanoparticles (NPs), as well as micro- and nanodendrites of zinc and tin oxides in silicate nanoporous glass (NPG) with the average pore size of 25 nm, are presented. Oxide nanoparticles were synthesized in the bulk of nanoporous glass by the method of thermodissociation of zinc and tin salts. Oxide nanodendrites were synthesized by the oxidation of zinc and tin nanodendrites which were grown in glass pores via the method of electrolysis. It is demonstrated that the luminescence of nanoparticles and nanodendrites of Zn and Sn is caused by defects in the crystal structure. The optical and dielectric properties of the nanocomposites with nanoparticles and nanodendrites are compared. The obtained results can be used to create chemical and biological sensors, as well as in photocatalysis.
Spectroscopy Study of Sm3+ Doped Fluorosilicate Glasses for Orange Emission Solid-State Device Application
Glass samples with formula as Li2O–BaO–GdF3–SiO2:Sm2O3 were fabricated by melt quenching method. Their optical, physical and luminescence properties were studied, for their potential applications in photonic device working in visible region. The Sm3+ ions and nearby ligands bonding nature were determined from bonding parameters (δ) that in turn were calculated from LGF absorption spectra. Oscillator strength of different absorption bands and Judd–Ofelt (JO) parameters (Ωλ (λ = 2, 4, 6)) were measured. JO-parameters and refractive index have been used to valuate various radiative properties of Sm3+ ions emission transitions in prepared glasses to explore their potential application as visible lasers. Furthermore, the emission was studied by exciting the LGF glass samples with different wavelengths (λex = 275, 402 nm). The orange to red ratios at different wavelengths (λex = 275 nm and X-ray) were evaluated to measure the Sm3+-ions local disorder in the glass network. The decreasing trend in experimental decay time (τexp) with Sm3+-ion concentration increasing was observed due to energy transfer. Best fit for the prepared glass, when studied in the light of Inokuti–Hirayama model was obtained for S = 6 indicating dipole–dipole type of energy transfer. The intense visible (orange) emission, high stimulated emission cross-section (σe), branching ratios (βR), radiative transition probability (AR), and reasonable quantum efficiency were determined for transition from 4G5/2 to 6H7/2 in glass. This suggests Sm3+ doped glass shows potential use for development of devices (laser and photonic) working in visible (orange) region.
Thermal Stability and Hardness Studies of Ge Doped Se–Te Glassy Alloys
The amorphous glassy alloys Se82 – xTe18Gex (x = 0, 4, 8, 12, at %) was synthesized using melt quench technique. Thermal stability was examined with the help of various parameters such as Dietzal parameter, Hruby parameter, Saad and Poulin and Lu and Liu parameters. Vicker hardness was obtained from Vicker hardness tester and other related thermo-mechanical properties such as volume of micro-voids, energy formation of micro-voids and modulus of elasticity were calculated.
Exploration of Nonlinear Optical Features of Ga2S3–La2S3 Glasses for Optoelectronic Applications
An opportunity to operate by laser-induced nonlinear optical efficiencies of Ga2S3–La2S3 glasses doped with Er3+ and La3+ ions in the visible and near-infrared spectral ranges was explored. The laser-stimulated nonlinear optical properties were studied. The observed laser power and temperature dependences of the laser-stimulated second-harmonic generation and third-harmonic generation confirm the huge role of anharmonic phonon subsystems. Due to an occurrence of local structural distortions, the efficiency of laser nonlinear optical generation has been enhanced. Simultaneous occurrence of the second and third-order nonlinear optical response may indicate on the possibility of multifunctional applications of the investigated glasses in different electronic devices.
Sm3+ Doped Lithium Strontium Borate Glasses for Solid State Lighting Applications
The glasses of samarium (0.1, 0.2, 0.5, 1.0, 1.5 and 2.0 mol %) doped lithium strontium borate samples were synthesized. The physical and optical properties are studied at ambient conditions and discussed in this study. XRD spectra reveals the no atomic order in structure (amorphous) present in these glasses. Infrared spectroscopic study reveals the structural units of borate viz., BO3 and BO4 group present in the matrix. Interestingly, it is found that as the rare earth concentration increases and beyond 1.5 mol % the luminescence intensity decreases due to non-bridging Sm3+ ions in the glass network. The peaks in absorption spectra are due to dipole transition from 6H5/2 to levels corresponds to (2S + 1)LJ excited states under the excitation wavelength of 402 nm. Judd–Ofelt theory applied to estimate dipole strength in terms of J–O parameters (Ω2, Ω4 and Ω6), oscillator strength (fexp and fcal), radiative transition possibility (AR), branching ratio (βR) and stimulated emission cross section (σ) of the glass samples. From Judd–Ofelt analysis the parameters obtained are shown for 1.50 mol % of Sm3+ doped lithium strontium borate (LSB) glasses studied, which were compared with other glasses. The obtained results suggest their potential candidature for using as solid state material lighting applications due their efficient orange emissions.
Physicochemical Properties of Glasses in SrO · B2O3–SrO · SiO2 Join
The physicochemical properties of glasses in the 50SrO · 50B2O3–50SrO · 50SiO2 join (mol %), such as density, microhardness, thermal expansion, and glass-transition temperature, are studied. Comparison with the characteristics of strontium-borosilicate glasses in other join with the constant strontium oxide content shows that the molar volume increases with an increase in the concentration of B2O3 and does not depend on the SrO content in the range of 50 to 35 mol %. It is determined that the glass-transition temperature decreases with the replacement of SiO2 by B2O3. The concentration dependences of the microhardness, thermal expansion coefficient above the glass transition region (αl), and the change of the thermal expansion coefficient in the glass transition region (Δα) have a maximum in the composition range rich in boron oxide.
Nucleation of CuCl in Glass at the Sample Heating Stage
The peculiarities of the nucleation of CuCl nanoparticles at the heating stage in sodium-aluminum-borosilicate glass are studied by the method of exciton-thermal analysis. It is found that the concentration of CuCl particles in this process reaches its maximum. The concentration of CuCl particles increases as the heating time increases, while the average radius decreases. The numerical simulation shows that heating leads to the development of the maximum number of new phase nuclei due to the rapid growth of the critical radius. From a certain moment of heating, the dissolution of previously formed nuclei is observed. The CuCl phase concentration and the average radius of the particles’ radial distribution under heating for more than 5 min tend to the equilibrium value for the corresponding nucleation temperature.
Effect of Common Daily Acidic Beverages on the Surface Roughness of Glass Ionomer-Based Dental Restorative Biomaterials
The aim of this study was to compare the effect of different immersion protocols into various acidic media on the surface roughness of various glass ionomer-based dental restorative materials in vitro. The total number of 200 specimens were prepared from 5 different restorative material groups. Ten specimens from each group were then immersed into one of the tested beverages including; Coca-Cola, Iced-Tea, orange juice and distilled water (control). All specimens were kept in oven at 37°C for designated time periods of 1 day, 1 week, 1 month, 3 months, 6 months and 1 year and solutions were renewed weekly. Surface roughness measurements were performed at baseline and after each immersion period. The surface roughness of all glass ionomer-based restorative materials were affected by immersion with acidic media to a degree. For Glass Carbomer, there were steady increases in surface roughness in Ice Tea and orange juice (p < 0.05). The only significant increase in surface roughness of Fuji IX was found in orange juice (p < 0.05). However, the difference was not significant in coke and ice tea in comparison to distilled water (p > 0.05). When compared with distilled water, surface roughness of Chemfil Rock had increased significantly in coke and orange juice (p < 0.05). Surface roughness values of F2000 had increased significantly in coke and ice tea compared with distilled water (p < 0.05). For Dyract XP, only significant increase was found in coke compared with distilled water (p < 0.05). In conclusion, compomers were determined as the most robust materials comparing the surface roughness of the other glass ionomer based materials particularly used in pediatric dentistry. The surface degradation following immersion with acidic media is a multifactorial process, not only the pH and composition of the acidic environment, but also the type and composition of the exposed restorative material have influence on this process.
Effect of Transition-Metal Ions (Ni2+, Cu2+ and Co2+) on the Electric and Dielectric Properties of Zinc Sodium Phosphate
In this work, the influence of transition-metal ions doping on the zinc phosphate glass has been investigated. To do so, a series of glass doped with Ni2+, Cu2+and Co2+ at different ratio (1, 2 and 5 mol %) was synthesized. The Fourier transform infrared spectra was used to elucidate the bonding system of the constituent atoms. The dielectric and conductivity properties were studied by impedance spectroscopy over a frequency range from 10–2 Hz to 1 MHz at different temperatures. The changes in the conductivity and activation energy dependon the chemical composition and indicate a changeover of the predominant conduction mechanism from ionic to polaronic. The results have shown a lower electrical conductivity for glass containing CuO. This is related to the lower depolymerization degree of the glass network by Cu2+ ions. The dielectric constant and dielectric loss increased with the temperature and decreased with the frequency for all glasses studied. The variation of the value s factor for all glass samples as the function of temperature agrees with the correlated barrier-hopping (CBH) model.
Application of BaTiO3/CoFe2O4–SiO2 Structure to Control the Electrical Properties of Composites
This work describes the preparation of an organic-inorganic composite and the study of its characteristics. Particles of core (BaTiO3)–shell (SiO2–CoFe2O4) type were used as inorganic composite. These inorganic particles are used for the preparation of composites based on poly(vinyl alcohol) cyanoethyl ether synthesized in an external direct magnetic field. It is determined that the dielectric permittivity of the composites formed in an external magnetic field at the optimal content of the magnetic phase (concentration of CoFe2O4 = 20.3%) is four times as large (ε = 460 at the frequency f = 1000 Hz) as that of analogous composites formed without a magnetic field.
Synthesis of Cu–SiO2 Core–Shell Using Ultrasonic Waves and Its Antibacterial Activity
In this study, we compared the final core–shell products produced in the presence or absence of ultrasonic waves and evaluated the antibacterial properties of the core–shell. When ultrasonic wave was used, a complete core–shell structure with a silica shell coated on an individual core particle could be observed. Transmission electron microscopy and energy dispersive X-ray spectroscopy were performed to confirm the shape of the core–shell structure formed in each case. In order to evaluate the antibacterial activity of the core–shell with the Cu core, their antibacterial activity was evaluated by the KS J 4206 and JIS Z 2801. The Cu–SiO2 core–shell showed a high level of microbial reduction and it also worked as filler in the glass powder.
Deposition of Films from a Mixture of Hexamethylcyclotrisilazane Vapor and Argon in Inductively Coupled Plasma
In an inductively coupled high-frequency discharge plasma, SiCxNy:H films are obtained from a mixture of hexamethylcyclotrisilazane vapor and argon at substrate temperatures of 100 to 400°C and a discharge power of 200 W. The simplest plasma components (nitrogen, cyan, silicon atoms, CH free radicals, and C2 dimers) are determined. Some physicochemical properties of the films, including the growth rate, types of chemical bonds, refractive index, transparency interval, and contact angle, are studied. The synthesized films have a polymer-like structure.
Activation of Zr0.95 – xY0.05O2:\({\text{Eu}}_{x}^{{{\text{3 + }}}}\) by Heat Treatment in an Electromagnetic Field of the Microwave Range
Specimens composed of Zr0.95 – xY0.05O2:\({\text{Eu}}_{x}^{{3 + }}\) (x = 0.01–0.15) are synthesized in a muffle furnace and activated by thermal treatment in an electromagnetic field of the microwave range. The conditions for the activation and concentration of Eu3+ in phosphor are optimized. Microwave heat treatment results in the growth of grains, reduces microstresses, and increases the fluorescent brilliance of the specimens by a factor of 2.4.
Immobilization of Eu3+ Ions in Zeolite Matrices in Order to Develop Solid-State Radioluminescent Light Sources
Immobilization of europium ions in the Rho, Beta, and paulingite zeolites using ion exchange is studied in order to search for the optimal alumosilicate matrix for the development of solid-state radioluminescent light sources. The phase composition, thermal stability, moisture adsorption ability, and spectral characteristics of the specimens are studied. It is determined that Beta zeolite possesses the highest sorption capacity, high chemical and thermal stability, a significant constant capacity by water, and the highest cation-exchange characteristics regarding Eu3+.
Comparative Analysis of Triply Periodic Minimal Surface Corundum Products Obtained by 3D Printing
The paper studies the properties of triply periodic minimal surface corundum products of the Schwarz primitive topology printed on different 3D printers. The possibility of an alternative technology, 3D plastic mold slip casting, is considered.
Preparation and Study of Porous Ceramics Based on Zirconium Dioxide for Endoprosthesis
A strong highly porous ceramic for endoprosthesis possessing open porosity and elasticity modulus values similar to those of bone tissue is prepared through the solid-phase sintering of specimens of the initial powders of the (ZrO2)0.97(Y2O3)0.03 and [(ZrO2)0.97(Y2O3)0.03]0.8(Al2O3)0.2 compositions with blowing agents. The dependence of the characteristics of the sintered ceramics on the composition of zirconium-containing powders and blowing agents is investigated.
Study of Fracture Mechanism of Machinable Mica Glass-Ceramics under Quasi-Static Conditions
In order to study the deformation and fracture mechanism of machinable mica glass ceramics under different loading modes, quasi-static uniaxial tensile and compression experiments are designed and analyzed based on the obtained quasi-static stress-strain curves at different strain rates, the macroscopic and microscopic fracture morphology of the samples and the nano-indentation experiment. The results show that mica glass ceramics are basically elastic brittle bodies. A very short “softening” section before the compression fracture is observed. There is a significant SD (tensile and compressive strength difference) effect, and the ratio of compressive to tensile strength is 14. The fracture mechanism of mica glass ceramics is related to the loading mode. The fracture mechanism is normal tensile fracture perpendicular to the loading axis under tensile loading. Under compressive loading, there is a mixed mode of distensile splitting and local shear failure. The microcrack is preferentially nucleated and extends to the weak interface at the junction of two phases, and the critical nucleation load is about 20 mN. The energy consumption mechanism of crack initiation and propagation at the weak interface and cleavage steps are the reason for the softening of the compression end curve.
Ceramic Matrix Composites Based on Lanthanum Orthophosphate for Disposal of High-Level Radioactive Waste
Ceramic matrix composites for solidification and disposal of actinide-rare-earth fraction of high-level waste (HLW) were prepared by sintering of nanosized powders of 0.8LaPO4–0.2Al2O3, 0.8LaPO4–0.2Y2O3 and 0.8LaPO4–0.2ZrO2 obtained from 0.8LaPO4 · nH2O–0.2Al(OH)3, 0.8LaPO4 · nH2O–0.2Y(OH)3 and 0.8L-aPO4 · nH2O–0.2ZrO(OH)2 precursors. These powders-precursors were synthesized via sol-gel technique. After heat treatment at 850°C powders of 0.8LaPO4–0.2Al2O3, 0.8LaPO4–0.2Y2O3 and 0.8LaPO4–0.2ZrO2 were obtained. Further powdered compositions were stepwise sintered to prepare ceramic composites which were supposed to be used as matrices for storage of HLW. Rate of La3+, Al3+, Y3+ and Zr4+ leaching from ceramic matrix composites in strength aqueous solutions of NaCl and Na2SO4 simulating underground brine typical for proposed location of HLW geological repository was estimated.
Ceramics Sintering from Corundum Powders Clad with Iodine Transmission
This paper describes the conditions and results of ceramics sintering from “core-shell” corundum powders. Sintered ceramics phase composition, structure and mechanical properties were studied.
Formation of Water Soluble and Stable Amorphous Ternary System: Ibuprofen/β-Cyclodextrin/PVP
The aim of this work is to investigate the solubility enhancement of ibuprofen by formation of stable amorphous ternary system (ibuprofen, polyvinylpyrrolidon, β-cyclodextrin) compared to the binary system (ibuprofen, β-cyclodextrin). Ibuprofen was co-milled at ambient temperature in presence of PVP K30 and β‑cyclodextrin. The characterization of obtained mixtures was carried out using X-ray diffraction, infrared spectroscopy, scanning electronic microscope, differential scanning calorimetry and spectroscopy (1H/13C). The dissolution test was carried out in order to evaluate the release rate profiles of ibuprofen in the prepared mixtures. A thermodynamically stable and water-soluble ternary system was obtained, the released amount of ibuprofen in the ternary system increased considerably in comparison to the pure drug. These results highlighted the effect of PVP which enhanced the aqueous solubility of the binary system ibuprofen/β-cyclodextrin in solid state by reinforcing intermolecular interactions and improving complexing abilities of β‑cyclodextrin.
Morphology of Blanks and Fiber of Quartz Glass
The surface relief of blanks and silica glass fibers is studied by atomic force microscopy. The temperature change during free cooling is recorded using an infrared pyrometer. The results of the measurements of the roughness of the blank and fiber could indicate the effect of the cooling time of the quartz glass (QG) on the morphology of its surface.
Influence of Heat-Treatment Conditions on the Optical Properties of Bismuth-Containing Composites Based on High-Silica Porous Glass
Bismuth-containing composite materials are synthesized by the impregnation of matrices of thermally modified porous glass (PG) in 0.5 M aqueous solutions of bismuth nitrate followed by heat treatment. The optical density spectra of the obtained materials are studied depending on the heat treatment temperature (400–870°C). When the temperature of the heat treatment is increased, the distribution of bismuth in the samples becomes more homogeneous. The heat treatment in the range of 650 to 870°C leads to the degree of bismuth oxidation changing from Bi3+ to Bi2+ ions with the formation of dimers and clusters of bismuth.
The Effect of Additives of Water-Soluble Glass on the Extraction of Alkali from Portland Cement
The phenomenon of suppressing the potassium alkaline activity of Portland cement in the early stages of hydration in the presence of sodium water-soluble glass is established.
Experimental and Theoretical Studies of the Mechanical Properties of 3D Printed Polyamide Products of the Schwarz Primitive Topology
Polyamide-12 products based on the Schwarz primitive topology with different values of parameter t are created by 3D printing. The samples are obtained by selective laser sintering using an EOS 3D printer. The experimental stress–strain curves are obtained. It is revealed that as parameter t increases the strength of the samples decreases. Computer simulation using the COMSOL Multiphysics software is performed.
Studying the Influence of Additives on Binding Cellulose Fibers by IR Spectroscopy
The paper is devoted to the investigation of the polymer additives’ influence on the strength properties of a sheet and to the analysis of the absorption bands related to the vibration of the groups that participated in the formation of the network of hydrogen bonds in the system: fiber–water–additive. The relation between the intensity of the absorption bands of the stretching vibration of the hydroxyl groups and the deformational vibrations of the water molecules and the functional groups with the sheet’s strength properties is presented.
Research on the Surface of Lead Silicate Glass after Resurfacing
The surfaces of lead silicate glass (LSG) S87-2 and S78-4 after resurfacing followed by washing in organic solvents are studied. It is shown that long-term treatment in organic solvents leads to the removal of the foreign layer that appears after the use of oil slurries during resurfacing.
Retraction Note to: Mechanical and Bioactivity Assessment of Wollastonite/PVA Composite Synthesized from Bentonite Clay