Vapor–Liquid Equilibrium of Binary Components of the BrCF<Subscript>2</Subscript>COOCH<Subscript>3</Subscript>–CF<Subscript>3</Subscript>COOH–BrCF<Subscript>2</Subscript>COOH–CF<Subscript>3</Subscript>COOCH<Subscript>3</Subscript> Quaternary System

Vapor–liquid equilibria of binary components of the BrCF₂COOCH₃–CF₃COOH–BrCF₂COOH–CF₃COOCH₃ quaternary system have been studied experimentally at constant pressure. The experiments have been carried out on a modified Sventoslavskii ebulliometer. Using the Aspen Plus software package, the appropriate models have been selected and the vapor–liquid equilibria for six binary systems have been simulated.     

Bimetallic Pd–Cu/ZnO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Pd–Cu/ZrO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts for methanol synthesis

Monometallic copper and bimetallic palladium-copper catalysts supported on ZnO–Al₂O₃ and ZrO₂–Al₂O₃ were prepared by conventional impregnation method and tested in methanol synthesis reaction under elevated pressure (3.5 MPa) in gradientless reactor at 220°C. The physicochemical properties of prepared catalytic systems were studied using BET, X-ray, TPR-H₂, TPD-NH₃ techniques. The promotion effect of palladium on catalytic activity and selectivity of copper supported catalyst in methanol synthesis reaction was proven. The highest activity of this system is explained by the Pd–Cu alloy formation.     

Photon interaction parameters for some ZnO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>–P<Subscript>2</Subscript>O<Subscript>5</Subscript> glasses

Some photon interaction parameters such as mass attenuation coefficient, effective atomic number, half value layer, mean free path and electron density for 15ZnO–(17.5–x)Al₂O₃–xFe₂O₃–67.5P₂O₅ glass system (x = 0, 7.5, 12.5, 17.5) and 15ZnO–(25–x)Al₂O₃–xFe₂O₃–60P₂O₅ glass system (x = 0, 25) have been investigated in the photon energy range of 1 keV to 100 GeV. It has been observed that all the photon interaction parameters for the selected glass systems vary with the photon energy. Among the selected glass systems, the sample 15ZnO–25Fe₂O₃–60P₂O₅ glass system shows maximum values for mass attenuation coefficients, effective atomic numbers, electron densities and minimum values for mean free path and half value layer in the entire energy grid.     

Mechanical,Structural and Thermal Properties of Transparent Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZnO–TeO<Subscript>2</Subscript> Glass System

Oxide based optical glass materials has important potential material in many applications from fiber optic to sensor due to the high transparency and amourphous structures. The objective of this study is to synthesize the novel optical glass materials based on the bismuth and aluminum contents to be able to determine the physical, chemical and mechanical properties by considering the systematic experimental steps. In this study, Bi₂O₃–Al₂O₃ based tellurite optical glasses have been prepared by using conventional melt quenching method as a function of the both Bi₂O₃ and Al₂O₃ compositions. There is a strong interactions between the glass former and modifier ions that might effect on the structure and mechanical properties. During the experimental steps, thermal, structural and mechanical properties of the prepared glass materials have been determined considering the DTA/DSC, FT-IR spectroscopy, SEM and Vicker’s hardness techniques, respectively. Thermal parameters, like glass transition, T_g, onset, T_x, crystallization, T_p, and melting, T_m, temperatures were obtained by using DTA scan.     

Structural heterogeneity of SiO<Subscript>2</Subscript>–Na<Subscript>2</Subscript>O–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> glass

It is shown that the phase heterogeneity of SiO₂–Na₂O–Al₂O₃ glass has a liquation and crystallization nature, the balance between which is determined by the conditions of their synthesis. An increase in the aluminum oxide content decreases the number of liquation and crystallization sites, and also the linear sizes of the crystalline formations without eliminating the phase separation due to the liquation. The area of metastable immiscibility in the SiO₂–Na₂O–Al₂O₃ system, which is determined by scanning electron microscopy, is probably wider than the area detected by the optical methods.     

Physical–chemical properties and conductivity of Na<Subscript>2</Subscript>O–SnO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> glass systems

The effect of tin(IV) oxide on the conductivity and chemical stability of sodium–silicate glass has been studied for five different glass compositions. Dilatometry and DSC were used to investigate the thermal behavior of the glass. The research into transport characteristics of the glass has shown that its conductivity is in the range of 2 × 10^–8–5 × 10^–7 S/cm at 25°C and 10^–3 S/cm at 300°C.     

Crystallization of CaO–MgO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> glass prepared by float process

CaO–MgO–Al₂O₃–SiO₂ (CMAS) glass was prepared by float process. The effects of TiO₂ and heat-treatment on properties and crystallization behaviors of float glasses were investigated by atomic force microscope, differential scanning calorimeter, X-ray diffraction, electron probe microanalyzer, field emission scanning electron microscope and viscosity test. The results showed that CMAS parent glasses produced by float process had a high surface flatness (Ra is less than 80.1 ± 0.1 nm) and low tin penetration (14 μm). When the concentration of TiO₂ increased from 3.51 to 5.01 wt %, the glass transition temperature was decreased, and the crystallization temperature was shifted from 913 to 887°C using differential scanning calorimeter. Field emission scanning electron microscope images showed that phase separation was discovered in CMAS parent glass (containing 3.51 wt % TiO₂) treated at 670°C. Diopside as a major crystalline phase was precipitated in CMAS glass-ceramics nucleated at 700°C for 30 min and followed by crystallization at 910°C for 30 min.     

Synthesis and physicochemical properties of a solid oxide nanocomposite based on a ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–Gd<Subscript>2</Subscript>O<Subscript>3</Subscript>–MgO system

A highly dispersive powder with a (ZrO₂)_0.92(Y₂O₃)_0.03(Gd₂O₃)_0.03(MgO)_0.02 composition and specific surface area of 150 m²/g has been synthesized via a method of coprecipitation of hydroxides with the subsequent cryochemical treatment of the gel. Nanoceramics based on the cubic modification of zirconium dioxide with the grain size of ~40–45 nm have been obtained. The temperature dependence of the specific electrical conductance of the nanoceramics within a temperature range of 350–870°C in air has been studied, and the ratio of the ionic and electronic parts of the conductance has been determined. Recommendations for the use of the obtained oxide nanocomposite as an electrolyte for a high-temperature fuel cell have been given.     

Vitreous region and properties of glasses of the Ga<Subscript>2</Subscript>S<Subscript>3</Subscript>–GeS<Subscript>2</Subscript>–PbF<Subscript>2</Subscript> system

Vitrification in the Ga₂S₃–GeS₂–PbF₂ system is considered. The physicochemical properties of glasses, such as density, microhardness, electroconductivity, refraction index, and transmission percentage of specimens in visible and IR ranges of spectrum are studied; differential thermal analysis is carried out; and Raman and electron paramagnetic resonance spectra are investigated.     

Physicomechanical properties of refractory Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–Si<Subscript>3</Subscript>N<Subscript>4</Subscript>–C materials with ACPC

A study has been made on the effects of the amount of silicon nitride and graphite on the physicomechanical properties of Al₂O₃–Si₃N₄–C composites for lining purposes. Adding 2.5–5.0 wt.% silicon nitride and 0.5 wt.% reactive alumina improves the properties, raises their apparent density, and increases the mechanical strength, while reducing the open porosity. Optimized compositions have been determined for refractory materials of Al₂O₃–Si₃N₄–C composition, and it has been found that to attain the higher values of physicomechanical properties the amount of graphite should constitute 5–10 wt.%.     

Structural analyses of RuO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript>/Ti and IrO<Subscript>2</Subscript>–RuO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript>/Ti anodes used in industrial chlor-alkali membrane processes

The morphology and composition of RuO₂–TiO₂/Ti and IrO₂–RuO₂–TiO₂/Ti anodes, which have been used for the production of chlorine for more than 10 years, were analyzed by various methods; such as high-resolution scanning electron microscopy, high-resolution Auger electron spectroscopy, electron probe X-ray emission microanalysis and X-ray diffraction analysis. Drastic changes in the surface morphology, including partial exfoliation of a small amount of the oxide layer and a reduction in the content of ruthenium species through dissolution, were observed for the RuO₂–TiO₂/Ti anode. For the IrO₂–RuO₂–TiO₂/Ti anode, on the other hand, there were moderate changes in the surface morphology and moderate dissolution of iridium and ruthenium species.     

Electrochemical study of the codeposition of Mg–Li–Al alloys from LiCl–KCl–MgCl<Subscript>2</Subscript>–AlCl<Subscript>3</Subscript> melts

This work presents a novel electrochemical study on the codeposition of Mg, Li and Al on a molybdenum electrode in LiCl–KCl–MgCl₂–AlCl₃ melts at 943 K to form Mg–Li–Al alloys. Cyclic voltammograms (CVs) showed that the underpotential deposition (UPD) of magnesium on pre-deposited aluminum leads to the formation of a liquid Mg–Al solution, and the succeeding underpotential deposition of lithium on pre-deposited Mg–Al leads to the formation of a liquid Mg–Li–Al solution. Chronopotentiometric measurements indicated that the codeposition of Mg, Li and Al occurs at current densities lower than −0.47 A cm⁻² in LiCl–KCl–MgCl₂ (0.525 mol kg⁻¹) melts containing 0.075 mol kg⁻¹ AlCl₃. Chronoamperograms demonstrated that the onset potential for the codeposition of Mg, Li and Al is −2.100 V, and the codeposition of Mg, Li and Al is formed when the applied potentials are more negative than −2.100 V. The diffusion coefficient of aluminum ions in the melts was determined by different electrochemical techniques. X-ray diffraction and inductively coupled plasma analysis indicated that α, α + β and β Mg–Li–Al alloys with different lithium and aluminum contents were obtained via potentiostatic and galvanostatic electrolysis.     

Physicochemical Properties of Nanosized Powders of the LaPO<Subscript>4</Subscript>–DyPO<Subscript>4</Subscript>–H<Subscript>2</Subscript>O System

Nanosized La_1–xDy_xPO₄ · nH₂O powders are synthesized by the sol-gel method using direct and reverse precipitation. The formation of a continuous series of hexagonal solid solutions based on LaPO₄ · nH₂O is confirmed by the XRD and DSC/TG methods. A continuous series of monoclinic solid solutions based on LaPO4 is formed at temperatures higher than 600°C. A reflex corresponding to a tetragonal form of DyPO₄ is formed during the calcination of DyPO₄ powder at 850°C. Two types of solid solutions are observed at temperatures of 1000–1200°C, namely, monoclinic solutions based on LaPO₄ (to x ≈ 0.7) and tetragonal solutions based on DyPO₄ (0.90 ≤ x ≤ 1.0). The results are compared depending on the methods of nanopowder synthesis.     

Synthesis of the study of solid solutions based on the ZrO<Subscript>2</Subscript>–HfO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript>(CeO<Subscript>2</Subscript>) system

The results of the studies of the conditions of the liquid-phase synthesis of highly dispersed xerogels with a low degree of agglomeration and precursor nanopowders (~10–12 nm) based on zirconium dioxide in the ZrO₂–HfO₂–Y₂O₃(CeO₂) system are presented. The thermal decomposition of xerogels and formation of crystalline solid solutions with the structure of fluorite are investigated. The optimal conditions for the solidification of nanodispersed powders for fabricating compact ceramics based on solid solutions of ZrO₂ and the physical–chemical properties of these ceramics are studied.     

Synthesis and characterization of nanocomposites Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>–SiO<Subscript>2</Subscript>–chitosan based on lbl technology

In this paper, the apparent chain-like core-shell structure Fe₃O₄–SiO₂–chitosan nanoparticles was synthesized by two-step method with cross-linking action of glutaraldehyde based on layer-by-layer technology, the composite particles were characterized by IR, XRD, TEM, SEM, EDS and VSM analytical methods, and the synthesis conditions of the product were studied. The results indicated that the diameter of the composite particles is about 106.5 nm, the parietal layer of chitosan is 20 nm, and after crosslinking action of glutaraldehyde, chitosan uniformaly coated the outer surface of Fe₃O₄–SiO₂.     

Hydroisomerization of Benzene-Containing Gasoline Fraction on Pt/B<Subscript>2</Subscript>O<Subscript>3</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Pt/WO<Subscript>3</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts

The effect of the hydroisomerization conditions of the benzene-containing fraction of catalytic reforming gasoline on the yield and composition of products is studied on Pt/B₂O₃–Al₂O₃ and Pt/WO₃–Al₂O₃ catalysts. These catalysts allow benzene to be completely removed from the raw material. At the same time, the greatest yields of liquid products are obtained with minimal losses of the octane number at 2 MPa, a mass feedstock hourly space velocity (MFHSV) of 2 h^?1, and 325°C: 96.3 and 95.4 wt % on Pt/B₂O₃–Al₂O₃ and Pt/WO₃–Al₂O₃ catalysts, respectively. The activity of the catalysts is maintained for 100 h during their operation.     

Phase relationships in the Na<Subscript>2</Subscript>ZnP<Subscript>2</Subscript>O<Subscript>7</Subscript>–LiKZnP<Subscript>2</Subscript>O<Subscript>7</Subscript> system

The phase relationships in the Na₂ZnP₂O₇–LiKZnP₂O₇ system are studied. They are represented by a mixture of the starting components in the subsolidus region. The eutectic was found at a temperature of 640°C and composition of 0.5LiKZnP₂O₇. The phase formation of this system is compared with the previously studied NaKZnP₂O₇–LiKZnP₂O₇ system. It is shown that a structural factor affects the geometry of the state diagrams.     

Study of the influence of extra-framework cations and organic templates on zeolite crystallization in SiO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–Na<Subscript>2</Subscript>O–K<Subscript>2</Subscript>О (R<Subscript>2</Subscript>O,RO) systems

Crystallization of zeolites from the gels of the (3–x)К₂О–xR₂O(RO)–0.05Na₂O–Al₂O₃–5SiO₂–100H₂O composition where x was varied from 0 to 3 and R = Li, Na, Rb, Cs, Ba, tetraethylammonium, tetrapropylammonium, and tetrabutylammonium, has been performed by hydrothermal synthesis. The influence of various cationic ratios on the final product of crystallization depending on the synthesis temperature has been studied at constant SiO₂: A₂lO₃ and H₂O: SiО₂ ratios. The correlation between the cationic composition of the initial gels, their structure, and the structure of the crystallizing zeolites has been estimated.