Structural Arrangement of Fe–Sb–O Catalysts

In iron–antimony catalysts containing excess antimony oxide and consisting of a mixture of FeSbO₄ and -Sb₂O₄ phases, the structure of iron antimonate changes compared to the catalyst with an equimolar composition, which is the pure FeSbO₄ phase. In the presence of excess antimony oxide in the near-surface layer of iron antimonate, extended defects with a structure of crystallographic shift are formed. These accumulate overstoichiometric antimony. Such a structural change is associated with changes in the acid–base properties and the surface oxygen binding strength.     

Comparative thermodynamic study of Ga–In–Sb system

The results of comparative thermodynamic analysis of Ga–In–Sb system are presented in this paper. Investigations, carried out in the section from Ga corner with molar ratio of In:Sb equal to 1:1, were done experimentally, using Oelsen calorimetry at the temperature 873 K and analytically, applying different calculation methods—Toop and Muggianu, in the temperature interval from 873 to 1673 K. Excess molar Gibbs energies and activity of all components in specified temperature interval were calculated.     

Preparation of onion-like Pd–Bi–Au/C trimetallic catalyst and their application

This paper describes the preparation of dispersed onion-like Pd–Bi–Au/C catalyst with average diameter of 13 nm obtained by consecutive chemical reduction of precursor gold, bismuth and palladium salts in aqueous solution and immobilization on active carbon. High-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Auger electron spectroscopy experiments were performed to analyze the structure and to characterize the Pd–Bi–Au/C catalyst. The onion-like morphology is composed of high content of gold inner core, a Bi-rich intermediate layer and a Pd-rich external layer. The catalytic activity of the catalyst was subsequently investigated and they were found to be efficient catalysts for the aerobic liquid phase oxidation. The results showed that the catalytic activity of Pd–Bi–Au/C was higher than that of Pd–Au/C bimetallic catalyst, indicating that bismuth plays an important role in synergistic effect between gold and palladium.     

The effect of 60Co (γ-ray) irradiation on the electrical characteristics of Au/SnO2/n-Si (MIS) structures

The effect of ⁶⁰Co (γ-ray) irradiation on the electrical properties of Au/SnO₂/n-Si (MIS) structures has been investigated using the capacitance–voltage (C–V) and conductance–voltage (G/ω−V) measurements in the frequency range 1 kHz to 1 MHz at room temperature. The MIS structures were exposed to γ-rays at a dose rate of 2.12 kGy/h in water and the range of total dose was 0–500 kGy. It was found that the C–V and G/ω−V curves were strongly influenced with both frequency and the presence of the dominant radiation-induced defects, and the series resistance was increased with increasing dose. Also, the radiation-induced threshold voltage shift (ΔV_T) strongly depended on radiation dose and frequency, and the density of interface states N_ss by Hill–Coleman method decreases with increasing radiation dose.     

Influence of fluoride-doped tin oxide interlayer on Ni–Sb–SnO2/Ti electrodes

In the present work, fluoride-doped tin oxide (FTO) as an interlayer was introduced into nickel and antimony co-doped tin dioxide coated titanium electrodes to investigate the influence of FTO interlayer on the structural properties and lifetime performance of the electrodes. Scanning electron microscopy and X-ray diffraction techniques were used to characterize the morphology and crystal structure of the electrodes with or without FTO interlayer. The electrode surface became smoother with FTO interlayer introduced while the crystallite size reduced. Electrochemical impedance spectroscopy was also adopted to analyze the electrodes’ electrochemical behavior. With FTO interlayer introduced, the formation of titanium dioxide-insulating layer on the titanium substrate was significantly retarded during the anodic process. The accelerated lifetime tests presented that the lifetime of the electrodes with proper FTO interlayer was six times longer than that without FTO interlayer. The mechanisms for the electrodes’ lifetime enhancement with FTO interlayer were discussed.     

Adenine–Au and adenine–uracil–Au. Non-conventional hydrogen bonds of the anions and donator–acceptor properties of the neutrals

This is a study of adenine–Au and adenine–uracil–Au (neutral, anionic and cationic), applying the B3LYP density-functional approach. In these systems, the interaction is directly related to the charge; so that as the metal atomic charge increases, the bond strength also increases. Neutral molecules are weakly bonded, the interaction in the case of cations is mainly electrostatic and in the case of the anions, the extra electron is localized on the metal atom and consequently, non-conventional hydrogen bonds are formed. In the case of adenine–Au (anion), the H dissociation energy is similar to the electron dissociation energy, and therefore both reactions may be possible. Moreover, the Au anionic atom modifies the hydrogen bonds of the uracil–adenine base pair. This may be significant in the study of point mutations that may occur in the Watson–Crick dimmer of nucleic basis. The electron-donator properties of these compounds are analyzed with the aid of the donator–acceptor map (DAM), previously described. Adenine–Au, uracil–Au and adenine–uracil–Au are more effective electron donors, but poorer electron acceptors than adenine, uracil and adenine–uracil. If the electron acceptor properties of carotenoids such as β-carotene and astaxanthin are compared, there are indications that astaxanthin may act as an oxidant instead of an antioxidant with the uracil–adenine base pair. The oxidation of nucleic acid bases by carotenoids may have important consequences, as oxidative damage of DNA and RNA appears to be linked to cancer. This is something that demands further studies and for this reason, work concerning the reactivity of carotenoids with DNA-nitrogen bases is in progress.     

Crystal growth kinetics of Sb2S3 in Ge–Sb–S amorphous thin films

Sb₂S₃ crystal growth kinetics in (GeS₂) _x (Sb₂S₃)_1?Cx thin films (x?=?0.4 and 0.5) have been investigated through this study by optical microscopy in the temperature range of 575?C623?K. Relative complex crystalline structures composed of submicrometer-thin Sb₂S₃ crystal fibers develop linearly with time. The data on temperature dependence of crystal growth rate exhibit an exponential behavior. Corresponding activation energies were found to be E _G?=?279?±?7?kJ?mol^?1 for x?=?0.4 and E _G?=?255?±?5?kJ?mol^?1 for x?=?0.5. These values are similar to activation energies of crystal growth in bulk glasses of the same compositions. The crystal growth is controlled by liquid?Ccrystal interface kinetics. It seems that the 2D surface-nucleated growth is operative in this particular case. The calculated crystal growth rate for this model is in good agreement with experimental data. The crystal growth kinetic characteristic is similar for both the bulk glass and thin film for x?=?0.4 composition. However, it differs considerably for x?=?0.5 composition. Thermodynamic and kinetic aspects of crystal growth are discussed in terms of Jackson??s theory of liquid?Ccrystal interface.     

Thermodynamic evaluation of viscosity in In–Zn and Sn–Zn liquid alloys

A theoretical formalism that links thermodynamic properties to transport properties has been used to study the viscosity of Sn–Zn and In–Zn liquid alloys at various temperatures. The formalism was successful at describing the thermodynamic properties of these alloys and showed a better estimation of the viscosity of the Sn–Zn alloy than that of the In–Zn alloy.     

Thermoanalytical study and structure of stoichiometric As–Sb–S glasses

The glass-forming system (As₂S₃)_100?x(Sb₂S₃)_x was studied by thermal analysis (conventional and StepScan differential scanning calorimetry) and Raman spectroscopy. It was found that the bulk glasses are homogeneous up to x = 60, while supercooled melts are unstable and when x ≥ 40, Sb₂S₃ (stibnite) crystallizes during heating. Depending on the chemical composition, the glass transition temperature initially increases as the Sb₂S₃ concentration is increased from 0 to 5 %, decreases to a minimum at ~20 %, and then gradually increases as the concentration is further increased and the main Raman peak also shifts non-monotonically. Combining these results with chemometric analysis of the Raman spectra showed that the image of the structure of the studied glasses can be described by the linear combination of three chemically different stable clusters, rather than by the chains crossing model, CCM, and that the properties of the glasses are controlled by medium-range order.     

Ternary invariant point at 403 and 455?°C in the Al–Sb–Zn system

The temperature and location of the invariant eutectic point at 403?°C in the zinc-rich corner of the Al?CSb?CZn system was determined. However, the experimentally determined temperature was found to be lower than the thermodynamically predicted one. Differential thermal analyses, differential scanning calorimetry, and quantitative microstructural analyses were used to determine this specific reaction. The determined ternary eutectic reaction, L??????-Sb₂Zn₃?+?AlSb?+???-Zn, represents the last solidification path in the phase region of Sb?CAlSb?CZn. Before a ternary eutectic reaction takes place, another reaction is also possible near the Sb?CZn binary system, a quasi-peritectic reaction at 455?°C: L?+???-Sb₂Zn₃????AlSb?+???-Sb₂Zn₃. A scanning electron microscope equipped with an energy-dispersive spectrometer was used for the microstructural analyses. The phase identification was conducted with X-ray diffractometry. The experimental data were compared to the thermodynamic predictions made with the CALPHAD method using the SSOL4 database.     

Electroreduction of α-glucose on CNT/graphite electrode modified by Zn and Zn–Fe alloy

Electroreduction of -glucose to form sorbitol on Zn/CNTs and Zn alloy/CNTs electrodes has been investigated in this paper. Carbon nanotubes (CNTs) used in this paper are grown directly on graphite disks by chemical vapor deposition. Zn and Zn alloy are electrodeposited on the activated CNTs/graphite electrode by pulse galvanostatic method. The micrographs of Zn/CNTs and Zn alloy/CNTs electrodes are characterized by scanning electron microscopy. The results show that the current efficiency of -glucose reduction on CNTs electrodes is much better than that on flat Zn electrodes. The order of the current efficiency on different electrodes is as follows: Zn/CNT (0.58) Zn–Fe/CNT (0.57)>Zn–Ni/CNT (0.43) Zn/graphite (0.42)>Zn (0.40). It indicates that CNTs have good potential application in electrosynthesis. Additionally, effects of some operating parameters, such as pH, temperature and -glucose concentration, on the current efficiency of -glucose reduction are also discussed.     

Enthalpies of mixing of liquid systems for lead-free soldering: Cu–Sb–Sn system

Using two different types of high temperature drop calorimeters, partial and integral enthalpies of mixing of liquid alloys were determined in the ternary Cu–Sb–Sn system. The system was investigated along four sections at 1100 K. Experimental data were used to find ternary interaction parameters by applying the Redlich–Kister–Muggianu model for substitutional solutions, and a full set of parameters describing the concentration dependence of the enthalpy of mixing was derived. From these, the isoenthalpy curves were constructed for 1100 K. The entire system shows exothermic enthalpy of mixing at the given temperature.     

Effect of hydrothermal aging on NOx reduction performance for Sb–V–CeO2/TiO2 catalyst

Research on Chemical Intermediates - Herein, we investigated the NOx reduction performance of Sb–V–CeO2/TiO2 (SbVCT) catalyst subjected to hydrothermal aging, where 6 vol% of H2O was...     

Thermodynamic and surface properties of Ge–Ga and Ge–Sb liquid alloys

Thermodynamic and surface properties of Ge–Ga and Ge–Sb liquid alloys have been studied using statistical mechanical formulations based on complex formation and that based on the concept of layered structure near the interface. The study showed that low level of complex formation of the form Ge _{2 Sb} exists in Ge–Sb toward the Ge-rich end of the concentration range and the surface properties of Ge–Ga are almost equal to their corresponding bulk equivalent.     

The Structure of Oxide Ga–Sb–Ni–P–W–O/SiO2 Catalyst and Its Catalytic Properties in Propane Ammoxidation

The structure of the multicomponent catalyst Ga₁Ni₁P₂W_0.5Sb₆O _x /SiO₂ and its catalytic properties in propane ammoxidation are studied. The catalyst is nanostructured and consists of noncoherently spliced blocks of a multiply promoted phase with a structure of gallium antimonate, which covers SiO₂ particles with a thin layer. In the multiply promoted compound with a structure of gallium antimonate, Ni²⁺ ions partially substitute for Ga³⁺ and W⁶⁺ ions partially substitute for Sb⁵⁺. This leads to an increase in the crystalline lattice parameters a and c. Phosphate ions are stabilized in the region of block interfaces. The catalyst is characterized by high efficiency in propane ammoxidation.     

Thermal Synthesis of the Zn1–xCOxO Pigments

In our laboratory, the synthesis of new inorganic pigments is followed by thermal analysis using a derivatograph apparatus. First information about the temperature region of the formation of the pigments investigated is provided by thermal analysis. The attention was directed to the preparation of the pigments based on zinc oxide in new green hues which can be used as medium colour pigments. This revised version was published online in August 2006 with corrections to the Cover Date.     

In-situ green synthesis of highly active GSH-capped Pt–Au–Ag-hybrid nanoclusters

Recently much attention has been paid to the application of metal hybrid nanoparticles in industrial catalytic fields because of their super-efficient catalytic activity and attractive properties. We explored a novel strategy to prepare GSH-capped Pt–Au–Ag-hybrid nanoclusters through the synergistic effect between ascorbic acid(VC) and glutathione(GSH) with chloroplatinic acid, chloroauric acid, and silver nitrate as precursors. The potential utilization of as-prepared GSH-capped Pt–Au–Aghybrid nanoclusters for catalytic applications has been evaluated through the reduction of 4-nitrophenol(4-NP) with NaBH4; we obtained the kinetic data by monitoring with UV-Vis spectroscopy. Our results illustrate that GSH-capped Pt–Au– Ag-hybrid nanoclusters could facilitate the process of reduction of 4-NP in a way that is unprecedented. This approach may offer a novel, non-cytotoxicity, efficient catalyst for industry.     

Experimental investigation and thermodynamic modeling of the Au–Ge–Ni system

Abstract  

Phase equilibria in the Au–Ge–Ni ternary system were studied by means of scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and differential scanning calorimetry. The phase relations in the solid state at 600 °C as well as a vertical section at Au₇₂Ge₂₈–Ni were established. No ternary compound was found at 600 °C. On the basis of the experimental phase equilibria data, a thermodynamic model of the Au–Ge–Ni ternary system was developed using the CALPHAD method. Thermodynamically calculated phase diagrams are shown at 600 °C, in two vertical sections and the liquidus projection. Reasonable agreement between the calculations and the experimental results was achieved.     

Glass transition and crystallization kinetics analysis of Sb–Se–Ge chalcogenide glasses

Differential thermal analysis (DTA) has been employed to investigate the effect of Ge addition on the glass transition behavior and crystallization kinetics of Sb₁₀Se_90?xGe_x (x = 0, 19, 21, 23, 25, 27) alloys. The three characteristic temperatures viz. glass transition (T _g), crystallization (T _c), and melting (T _m) have been determined and found to vary with the heating rates and Ge content. Thermal stability and glass forming tendency have been evaluated in terms of ΔT (= T _c ? T _g) and reduced glass transition temperature. The activation energies for glass transition and crystallization have been used to analyze the nucleation and growth process. The activation energy analysis also determines the suitability of alloys to be used in switching applications. Results have been interpreted in terms of bond energies and structural transformations in the investigated alloys.