Fabrication and Magnetic Properties of Fe<Subscript>65</Subscript>Co<Subscript>35</Subscript>–ZnO Nano-Granular Films

A series of nano-granular films composed of magnetic metal (Fe₆₅Co₃₅) granules with a few nanometers in size and semiconductor oxide (ZnO) have been fabricated by a magnetron sputtering method, and excellent soft magnetic properties have been achieved in a wide metal volume fraction (x) range for as-deposited samples due to the exchange coupling between FeCo granules (a ferromagnetic interaction in nano-scale). In a wide range (0.53 < x < 0.71), the films exhibit coercivity H _C not exceeding 15 Oe, along with high resistivity. Especially for the sample with x = 0.67, coercivities in hard and easy axes are 1.43 and 7.08 Oe, respectively, 4πM _S  = 9.85 kg, and ρ reaches 2.06 × 10³ μΩ cm. The dependence of complex permeability μ = μ′ − jμ″ on frequency shows that the real part μ′ is more than 100 below 1.83 GHz and that the ferromagnetic resonance frequency reaches 2.31 GHz, implying the promising for high frequency application. The measured negative temperature coefficient of resistivity reveals that may be the weak localized electrons existing in samples mediate the exchange coupling.     

Preparation of sulfide ceramic materials based on BaSm<Subscript>2</Subscript>S<Subscript>4</Subscript>and CaGd<Subscript>2</Subscript>S<Subscript>4</Subscript> with the use of sol-gel and cryochemical technologies

Solid solutions in the MeLn₂S₄?x (mol %) MeS (Ln₂S₃) (Me = Ca, Ba; Ln = Sm, Gd) systems are prepared. The regions of solid solution formation are determined, the unit cell parameters of the crystal lattice are calculated, the total conductivity is investigated, and the activation energies for electrical conduction are calculated for samples with different prehistories. The electrolytic properties of phases based on calcium and barium thiolanthanates are studied, and the mechanism of defect formation is proposed.     

Investigation of a new lead-free Bi<Subscript>0.5</Subscript>(Na<Subscript>0.40</Subscript>K<Subscript>0.10</Subscript>)TiO<Subscript>3</Subscript>-(Ba<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>)TiO<Subscript>3</Subscript> piezoelectric ceramic

Lead-free piezoelectric compositions of the (1-x)Bi_0.5(Na_0.40K_0.10)TiO₃-x(Ba_0.7Sr_0.3)TiO₃ system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050°C and 1,175°C for 2 h. The effect of (Ba_0.7Sr_0.3)TiO₃ [BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was 1,125°C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the BNKT ceramic. A large room-temperature dielectric constant, ε _r (1,609), and piezoelectric coefficient, d ₃₃ (214 pC/N), were obtained at an optimal composition of x = 0.10.     

Transport properties of solid electrolytes based on <Emphasis Type="Italic">Me</Emphasis>Sm<Subscript>2</Subscript>S<Subscript>4</Subscript>

The solid-solution regions in the MeSm₂S₄-MeS and MeSm₂S₄-Sm₂S₃ (Me = Ca, Ba) systems are revealed. The average ion, cation, and anion transport number of the synthesized solid electrolytes xSm₂S₃[Ca(Ba)S] · (100 ? x)Ca(Ba)Sm₂S₄ (x = 1?10 mol %) are determined by the electromotive force (emf) method with the use of concentration cells with and without transfer. In the phases under investigation, the ion transfer in the temperature range 673–723 K is provided by sulfide ions (\(t_{S^2 } \) = 1.00±0.02). The diffusion coefficients of S^2? ions in the solid electrolytes are determined by potentiostatic chronoamperometry. A vacancy mechanism of defect formation is proposed. It is demonstrated that the transport characteristics of the solid electrolytes based on the CaSm₂S₄ compound are worse than those of the solid electrolytes based on the BaSm₂S₄ compound.     

Low-temperature anti-icing reagents in the Ca(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-Mg(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-CO(NH<Subscript>2</Subscript>)<Subscript>2</Subscript>-H<Subscript>2</Subscript>O system and their properties

The polytherms of ice melting in sections of the Ca(NO₃)₂-Mg(NO₃)₂-CO(NH₂)₂-H₂O system with different component ratios were studied in the temperature interval from 0 to −40°C. A series of nitrate and nitrate-carbonate reagents that are promising for the creation of anti-acing reagents were found, which form eutectics with ice at temperatures from −25 to −39°C. Their properties, viz., melting properties with respect to ice and corrosiveness on metals and alloys, were determined. An effective corrosion inhibitor was selected.     

Promoting Effect of Triglyme on Lean NO<Subscript>x</Subscript> Reduction Over Ag/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

The highly oxygenated hydrocarbon triethylene glycol dimethyl ether or triglyme (CH₃O–(C₂H₄O–)₃CH₃) was found to efficiently reduce NO_x under lean conditions over Ag/Al₂O₃, but gave a low NO_x conversion over Cu-ZSM-5. Furthermore, triglyme showed an extraordinary promoting effect when added together with propene as reducing agent for NO_x over Ag/Al₂O₃ at low temperature. This is most likely due to that triglyme promotes the activation of propene.     

Study on the properties of Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-B<Subscript>2</Subscript>O<Subscript>3</Subscript>-BaO lead-free glass using in the electronic pastes

The Sb₂O₃ doping lead-free glass in Bi₂O₃-B₂O₃-BaO ternary system were prepared in the composition of several different subsystem, and the glass powder was produced through the process of water quenching. Glass transition temperatures (T _g ), glass soften temperatures(T _s ), the volume resistivity (ρ) in the temperature range of 80–200°C, and linear thermal coefficients of expansion in the temperatures range of 25–300°C (α_25–300) were measured for subsystems along with the different ratio of Bi₂O₃, B₂O₃ and BaO. For these subsystems, T _g ranged from 458 to 481°C, and T _s ranged from 490 to 512°C, both decreasing with the increasing of Bi₂O₃/B₂O₃ ratio, and increasing with the increasing of BaO/B₂O₃ ratio. The measured α_25–300 ranged from 65.3 to 76.3 × 10⁻⁷ K⁻¹, with values increasing with increasing Bi₂O₃/B₂O₃ and BaO/B₂O₃ ratio. The volume resistivity remains at a high standards, which may caused by it’s non-alkali composition, and it fluctuated from 10¹³ to 10¹¹ Ω cm with the temperature varied from 80–200°C. The structure of Bi₂O₃-B₂O₃-BaO ternary leadfree glass system was mearsured by FT-IR. The IR studies indicate that these glasses are made up of [BiO₆], [BO₃], and [BO₄] basic structural units, and it appears that Ba²⁺ acts as a glass-modifier in this ternary system, but the Bi³⁺ has entered the glass network when it is in relative high content so as to change the α_25–300, T _s and T _g .     

Photoreduction of CO<Subscript>2</Subscript> into CH<Subscript>4</Subscript> using Bi<Subscript>2</Subscript>S<Subscript>3</Subscript>-TiO<Subscript>2</Subscript> double-layered dense films

Nano-sized bismuth sulfide (Bi₂S₃) and titanium dioxide (TiO₂) with the orthorhombic and anatase tetragonal structures, respectively, were synthesized for application as catalysts for the reduction of carbon dioxide (CO₂) to methane (CH₄). Four double-layered dense films were fabricated with different coating sequences—TiO₂ (bottom layer)/Bi₂S₃ (top layer), Bi₂S₃/TiO₂, TiO₂/Bi₂S₃: TiO₂ (1 : 1) mix, and Bi₂S₃: TiO₂ (1 : 1) mix/Bi₂S₃: TiO₂ (1 : 1) mix—and applied to the photoreduction of CO₂ to CH₄; the catalytic activity of the fabricated films was compared to that of the pure TiO₂/TiO₂ and Bi₂S₃/Bi₂S₃ doubled-layered films. The TiO₂/Bi₂S₃ double-layered film exhibited superior photocatalytic behavior, and higher CH₄ production was obtained with the TiO₂/Bi₂S₃ double-layered film than with the other films. A model of the mechanism underlying the enhanced photoactivity of the TiO₂/Bi₂S₃ double-layered film was proposed, and it was attributed in effective charge separation.     

Glass formation and the phase diagram of crystalline components in the Sb<Subscript>2</Subscript>S<Subscript>3</Subscript>-PbI<Subscript>2</Subscript> system

Glasses in the Sb₂S₃-PbI₂ system are synthesized, and their physicochemical properties are investigated. The glasses possess high refractive indices (up to 3 or greater). The phase diagram of the Sb₂S₃-PbI₂ system is constructed from the data of differential thermal and X-ray powder diffraction analyses. The diagram exhibits an eutectic behavior. The eutectic is located at a content of 47 mol % PbI₂ and at a temperature of 370 ± 5°C.Original Russian Text Copyright © 2004 by Fizika i Khimiya Stekla, Samoilenko, Mohammad Arif, Novikov, Filatov, Blinov.     

Electrochemical studies on Sr doped LaMnO<Subscript>3</Subscript> and LaCoO<Subscript>3</Subscript> layers synthesised in a low-pressure plasma reactor equipped with a convergent nozzle

The aim of this work was to synthesise and deposit a perovskite (La_1-x Sr _x MnO₃ or La_1-x Sr _x CoO₃) cathode on an SOFC electrolyte (8% Yttria Stabilised Zirconia – YSZ). The recombination of atomic oxygen on Sr doped LaMnO₃ was performed in order to study the properties of perovskite for the adsorption of oxygen. The electrical resistance of the layers was measured as a function of the chemical composition. Impedance measurements on different samples were performed in order to analyse the electrochemical response of the cathode – electrolyte stack as a function of temperature and nature of the atmosphere. Moreover, the Faradaic impedance representing the electrochemical processes at the cathode – electrolyte interface was calculated from the global impedance in various conditions.     

Electrochemical oxidation of an acid dye by active chlorine generated using Ti/Sn<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Ir<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> electrodes

The generation of active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of chloride ions (0.05 mol L⁻¹) and a low current density (5 mA cm⁻²) it was possible to produce up to 60 mg L⁻¹ of active chlorine on a Ti/Sn_0.99Ir_0.01O₂ anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated with in situ electrogenerated active chlorine on Ti/Sn_(1−x)Ir _x O₂ anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4, 25 mA cm⁻² and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus time reveal a zero order reaction at dye concentrations up to 1.0 × 10⁻⁴ mol L⁻¹. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed.     

Electrolytic properties of sulfide-conducting phases based on the BaLn<Subscript>2</Subscript>S<Subscript>4</Subscript> and CaLn<Subscript>2</Subscript>S<Subscript>4</Subscript> compounds of different structural types

The criteria for the choice of objects of investigation that possess sulfide-ion conduction, have the general formula MeLn₂S₄, and crystallize in different structural types are considered. The data obtained on the electrolytic properties of phases based on BaLn₂S₄(Ln = Nd, Sm, Tm); CaFe₂O₄ structural type), CaLn₂S₄(Ln = Y, Yb); Yb₃S₄ structural type), and CaLn₂S₄(Ln = Pr, Nd, Gd); Th₃P₄ structural type) are generalized. The performed comparative analysis of the properties of the synthesized electrolytes has demonstrated that the properties of solid electrolytes depend on the configuration of the f state of lanthanides to a greater extent than on the structure of the electrolytes under investigation. The vacancy mechanism of defects formation and sulfide-ion transfer in phases based on thiolanthanates is proposed reasoning from the data on the dependence of the electrolytic and thermodynamic properties on the composition.     

Relaxation phenomena in (As<Subscript>2</Subscript>Se<Subscript>3</Subscript>)<Subscript>100 − <Emphasis Type="Italic">x</Emphasis></Subscript>Bi<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> layers

The physical parameters, which describe the relaxation phenomena occurring in both the bulk and contact regions of the systems under investigation, have been calculated using experimental curves of isothermal relaxation of polarization current in thin films of modified (As₂Se₃)_{100 − x} Bi _x . The relation between the change in the internal structure of the studied materials and the processes of charge transfer and charge accumulation has been revealed. The results obtained have been discussed with invoking the relay-race mechanism of charge transfer.     

Crystallization Behavior of Amorphous Zr<Subscript>55</Subscript>Cu<Subscript>20</Subscript>Ni<Subscript>10</Subscript>Al<Subscript>10</Subscript>Ti<Subscript>5</Subscript> Alloy

In the present study, the crystallization behavior and thermal stability of amorphous Zr₅₅Cu₂₀Ni₁₀Al₁₀Ti₅ alloy, obtained by melt-spinning, have been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM). The activation energy for crystallization has been evaluated by the Kissinger method, and it has been found that E _x obtained from the crystallization onset temperature (T _x) is lower than E _p determined by the crystallization peak temperature (T _P). During the continuous annealing process, ZrO and h-Al₃Zr₅ phases firstly precipitate from the amorphous matrix, then Zr₂Ni_0.66O_0.33 phase forms continuously and its relative content increases with increasing annealing temperature. However, no crystalline phases have been observed during the isothermal annealing process at 733 K (below T _x) for 90 min. The atomic clusters can keep the stability state through adjusting the short-range ordering.     

Photoluminescence characteristics of Cd<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te single crystals grown by the vertical Bridgman method

In this paper, we report a systematic investigation of band-edge photoluminescence for Cd_1-x Mn _x Te crystals grown by the vertical Bridgman method. The near-band-edge emissions of neutral acceptor-bound excitons (labeled as L1) were systematically investigated as a function of temperature and of alloy composition. The parameters that describe the temperature variation of the energy were evaluated by the semiempirical Varshni relation. From the temperature dependence of the full width at half maximum of the L1 emission line, the broadening factors Γ(T) were determined from the fit to the data. The activation energies of thermal quenching were obtained for the L1 peak from the temperature dependence of the bound exciton peaks and were found to decrease with increasing Mn concentration.     

Simultaneous absorption of CO<Subscript>2</Subscript> and SO<Subscript>2</Subscript> into aqueous AMP/NH<Subscript>3</Subscript> solutions in binary composite absorption system

To enhance the absorption rate for CO₂ and SO₂, aqueous ammonia (NH₃) solution was added to an aqueous 2-amino-2-methyl-1-propanol (AMP) solution. The simultaneous absorption rates of AMP and a blend of AMP+ NH₃ for CO₂ and SO₂ were measured by using a stirred-cell reactor at 303 K. The process operating parameters of interest in this study were the solvent and concentration, and the partial pressures of CO₂ and SO₂. As a result, the addition of NH₃ solution into aqueous AMP solution increased the reaction rate constants of CO₂ and SO₂ by 144 and 109%, respectively, compared to that of AMP solution alone. The simultaneous absorption rate of CO₂/SO₂ on the addition of 1 wt% NH₃ into 10 wt% AMP at a p _A1 of 15 kPa and p _A2 of 1 kPa was 5.50×10⁻⁶ kmol m⁻² s⁻¹, with an increase of 15.5% compared to 10 wt% AMP alone. Consequently, the addition of NH₃ solution into an aqueous AMP solution would be expected to be an excellent absorbent for the simultaneous removal of CO₂/SO₂ from the composition of flue gas emitted from thermoelectric power plants.     

Wetting,surface tension,and work of adhesion of As<Subscript>2</Subscript>S<Subscript>3</Subscript> and As<Subscript>2</Subscript>Se<Subscript>3</Subscript> glass melts to quartz glass

The contact angles of the quartz glass surface by the As₂S₃ and As₂Se₃ glass melts and surface tension of these glass melts in the temperature range of 325–370°С have been experimentally measured. The polytherms are linear and possess negative slope in the mentioned temperature range. The work of the adhesion of As₂S₃ and As₂Se₃ glass melts to the quartz glass surface has been calculated and compared to the data on the adhesion strength of the As₂S₃–SiO₂ and As₂Se₃–SiO₂ boundaries of the solid phases.     

Structural investigation of glasses in the <Emphasis Type="Italic">x</Emphasis>(0.16GaCh<Subscript>2</Subscript> · 0.84GeCh<Subscript>2</Subscript>) · (1 − <Emphasis Type="Italic">x</Emphasis>)(SbCh<Subscript>1.5</Subscript>) (Ch = S,Se) system

The structure of glasses in the x(0.16GaCh₂ · 0.84GeCh₂) · (1 − x)(SbCh_1.5) (Ch = S, Se) system has been investigated using Raman scattering. The structure of glasses is interpreted as a superposition of the following structural units: Ge(Ga)Ch_4/2, Ch_3/2Ge(Ga)-Ge(Ga)Ch_3/2, SbCh_3/2, and -Ch-Ch-, where Ch = S and Se. The change in the fraction of the corresponding structural units with a change in the glass composition has been analyzed.     

Syndiospecific Polymerization of Styrene Using Half-Titanocene Catalyst Covalently Supported on MgCl<Subscript>2</Subscript>/AlEt<Subscript>n</Subscript>(OEt)<Subscript>3-n</Subscript>

The novel half-titanocene catalyst bearing reactive functional amino group, η⁵-pentamethylcyclopentadienyltri(p-amino-phenoxyl) titanium [Cp^∗Ti(p-OC₆H₄NH₂)₃], was easily synthesized by the reaction of η⁵-pentamethylcyclopentadienyltrichloride titanium (Cp^∗TiCl₃) with p-amino phenol in the presence of triethyl amine (NEt₃). Cp^∗Ti(p-OC₆H₄NH₂)₃ covalently anchored on MgCl₂/AlEt_n(OEt)_3-n support obtained from the reaction of triethylaluminium (AlEt₃) with the adduct of magnesium chloride (MgCl₂) and ethanol (EtOH), has been investigated and used to catalyze syndiospecific polymerization of styrene. Influences of the support structure, cocatalyst, and the molar ratio of Al in methylaluminoxane (MAO) and Ti (Al_MAO/Ti) on catalytic activity, syndiotacticity and molecular weight of the resultant polystyrene were investigated. Compared with the corresponding Cp^∗Ti(p-OC₆H₄NH₂)₃ homogeneous catalyst, a considerable increase in activity and molecular weight of syndiotactic polystyrene (sPS) was observed for the Cp^∗Ti(p-OC₆H₄NH₂)₃-MgCl₂/AlEt_n(OEt)_3-n supported catalyst even at a relatively low Al_MAO/Ti ratio of 50, and the kinetics of polymerization was stable during the reaction process.     

Thermoelectric Properties of <Emphasis Type="Italic">x</Emphasis>PbTe/Yb<Subscript>0.2</Subscript>Co<Subscript>4</Subscript>Sb<Subscript>12</Subscript> Hot-Pressed Samples

The xPbTe/Yb_0.2Co₄Sb₁₂ compounds were prepared by the ball-milling and hot-pressed process. Electrical conductivity of the composite samples are reduced with a increase in PbTe content; and, their temperature dependence coefficients show the positive values. The maximum electrical conductivity of composite materials is ~80000 Sm⁻¹ at 800 K. The Seebeck coefficient (absolute value) of the composite material is obviously improved with an increase in the dispersed phase (PbTe) content; the Seebeck coefficient (absolute value) of the 10PbTe sample is ~260 μVK⁻¹ at 700 K, which increases by 13.6% relative to that of the Yb_0.2Co₄Sb₁₂ sample. The thermal conductivity of the composite samples is improved due to introduction of PbTe, and the thermal conductivity of the 10PbTe sample is ~3 Wm⁻¹ K⁻¹ at 550 K. The maximum value of ZT is 0.78 at 700 K for the 2.5PbTe sample.