Preparation of Rod-like Aluminum Doped Zinc Oxide Powders by Sol-gel Technique Using Metal Chlorides and Acetylacetone Precursors

Al-doped ZnO(AZO) powders were prepared by using metal chloride precursors and the sol-gel technique. IR peaks observed at 1590 cm-1 and 1620 cm-1indicated the formation of metal chelate as a consequence of the addition of acetylacetone to the metal chloride solution. TG-DSC analysis of the AZO gels confirmed the formation of metal chelate as evidenced by the development of several weight loss peaks accompanied by the introduction of new endothermic peaks. The resulting AZO gels were annealed at 500, 600, and 800 ℃ to study the effect of annealing temperature. XRD and SEM results showed that crystallization of AZO gels takes place around 600 ℃. Hexagonal wurtzite structure was identified as the main phase for all the samples. In addition, small shift of the XRD(002) peak coupled with XPS results from the AZO powders confirmed the successful doping of the ZnO powders. Micron sized rod-like AZO powders were uniform in dimension and morphology and remained stable even at 800 ℃.

INTERACTION OF POLYVINYLPYRROLIDONE WITH METAL CHLORIDE AQUEOUS SOLUTIONS

Interactions of polyvinylpyrrolidone (PVP) with metal chlorides (MgCl 2 , CaCl 2 , KCl and BaCl 2 ) have been investigated by viscometric and spectrophotometric techniques in aqueous solutions. Intrinsic viscosity [η] of (PVP) has shown a discontinuity with varying concentration of metal chlorides. The decreasing order of effectiveness of cation is K 1+ > Ca 2+ > Mg 2+ > Ba 2+ for poly(vinylpyrrolidone) solution. Changes in the absorption spectra of the cosolutes were observed in the presence of PVP in the lower limit of the UV-visible region i.e. 200-210 nm. These changes were attributed to interaction of PVP molecules with the cosolute molecules. As the concentration of the cosolute increased, a red shift in the peaks was observed, indicating an increase in interaction between PVP and cosolutes.

Metal chlorides loaded on activated carbon to capture elemental mercury

Activated carbon （AC） was considered to be an effective sorbent to control mercury in combustion systems. However, its capture capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury （Hg 0 ） capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC to remove gaseous mercury. X-ray diffractometer （XRD）, thermogravimetric analyzer （TGA） and specific surface area by Brunauer- Emmett-Teller method （BET） analysis showed the main mechanisms： first, AC had an enormous surface area for loading enough MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl 2 might be released from AC’s porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg 0 oxidization may accelerate both oxidation and halogenation of Hg 0 . The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect of valence variable metal and chlorine oxidation.

Thermokinetic Study on the Complexation Reaction of the First-Row Transitional Metal Chlorides with Histidine

The enthalpy change of the complexation reactions of the first-row transitional metal chlorides including CrCl3, MnCl2, FeCl2, CoCl2, NiCl2 and CuCl2 with L--histidine in water were determined by a microcalorimeter at 298.15—323.15 K. The standard enthalpy of formation of 32Cr(His)+(aq) and 22M(His)+(aq) (M=Mn, Fe, Co, Ni and Cu) were calculated. Based on the thermodynamic and kinetic equations of the reactions, three thermody-namic parameters (the activation enthalpy, the activation entropy, the activation free energy), the rate constants, and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) are obtained. The solid complexes of CrCl3, MnCl2, FeCl2, CoCl2, NiCl2 and CuCl2 with histidine were prepared and identified as Cr(His)2Cl3H2O, Mn(His)2Cl24H2O, Fe(His)2Cl2H2O, Co(His)2Cl2H2O, Ni(His)2Cl2H2O and Cu(His)2Cl2H2O by chemical and elemental analyses. The bonding characteristics of these complexes were char-acterized by IR as well. The results showed that, with the atomic number increasing, three thermodynamic parame-ters, GD!, HD! and SD! of the complexation reaction of these metal chlorides with L-a-histidine in water present an analogy regularity.

Electric Field Induced Permanent Superconductivity in Layered Metal Nitride Chlorides HfNCl and ZrNCl

Devices of electric double-layer transistors （EDLTs） with ionic liquid have been employed as an effective way to dope carriers over a wide range. However, the induced electronic states can hardly survive in the materials after releasing the gate voltage VG at temperatures higher than the melting point of the selected ionic liquid. Here we show that a permanent superconductivity with transition temperature Tc of 24 and 15K is realized hi single crystals and polycrystalline samples of HfNCI and ZrNCI upon applying proper VG＇s at different temperatures. Reversible change between insulating and superconducting states can be obtained by applying positive and negative VG at low temperature such as 220K, whereas VG ＇s applied at 250K induce the irreversible superconducting transition. The upper critical field He2 of the superconducting states obtained at different gating temperatures shows similar temperature dependence. We propose a reasonable scenario that partial vacancy of Cl ions could be caused by applying proper VG＇s at slightly higher processing temperatures, which consequently results in a permanent electron doping in the system. Such a technique shows great potential to systematically tune the bulk electronic state in the similar two-dimensional systems.

Preparation and Properties of Cereal-Metal Complex Films

1 Results Various kinds of biodegradable polymer materials have been researched[1]. In our previous papers,cereals such as wheat,buckwheat,glutinous rice and nonglutinous rice were polycondenced with citric acid and polysilicic acid to prepare copolymer films respectively[2,3].These copolymer fims have relatively good mechanical properties but the water proofness is not so good.Recently,some cereals such as wheat,glutinous rice,nonglutinous rice,kaoliang,millet and maize were reacted with copper chlorid...

Absorption characteristics of elemental mercury in mercury chloride solutions

Elemental mercury （Hg^0） in flue gases can be efficiently captured by mercury chloride （HgCl2） solution. However, the absorption behaviors and the influencing effects are still poorly understood. The mechanism of Hg^0 absorption by HgCl2 and the factors that control the removal were studied in this paper. It was found that when the mole ratio of Cl^- to HgCl2 is 10：1, the Hg^0 removal efficiency is the highest. Among the main mercury chloride species, HgCl3^- is the most efficient ion for Hg^0 removal in the HgCl2 absorption system when moderate concentrations of chloride ions exist. The Hg^0 absorption reactions in the aqueous phase were investigated computationaIIy using Moller-Plesset perturbation theory. The calculated Gibbs free energies and energy barriers are in excellent agreement with the results obtained from experiments. In the presence of SO3^2- and SO2, Hg^2＋ reduction occurred and Hg^0 removal efficiency decreased. The reduced Hg^0 removal can be controlled through increased chloride concentration to some degree. Low pH value in HgCla solution enhanced the Hg^0 removal efficiency, and the effect was more significant in dilute HgCl2 solutions. The presence of SO4^2- and NO3^- did not affect Hg^0 removal by HgCl2.

Effects of CuCl_(2)·6H_(2)O and ZnCl_(2)·6H_(2)O on the viscosity of aqueous ethanol mixtures

The effects of CuCl_(2) and ZnCl_(2) on the viscosity in aqueous ethanol mixtures(10%–50%v/v)were studied in the concentration range 1.0×10^(–2)–8.0×10^(–2) mol·dm^(–3) at different temperatures.It was found that the viscosities increased with an increase in the concentration of the salts and percent composition of ethanol content,whereas it decreased with an increase in temperature.Ion-ion and ion-solvent interactions are determined with the help of A-and B-coefficients of Jones-Dole equation.The values of A-and B-coefficients are irregular and increase with a rise in temperature and also with an increase in ethanol contents for both salts.Negative values of B-coefficients show that ion solvent interactions is comparatively small and suggest that CuCl_(2) and ZnCl_(2) behave as structure breakers in aqueous ethanol mixtures.Thermodynamic parameters like the energy of activation(Eη)and change in entropy of activation(ΔS*)were also evaluated which confirm the structure breaker behavior of salts in aqueous ethanol mixtures.

Production Process and Properties of a Highly Porous Al Alloy Made Using NaCl Droplets as a Space Holder

Porous Al structures have been made using a porogen leaching method but with additional novel steps. In this way, Al-0.25Cu-0.6Si-1.0Mg alloys with interconnected, open cells have been made, with high levels of porosity（up to 89%）. The use of 4 to 5 mm diameter sodium chloride droplets combined with interspersion of the metal powder and droplets in the die and dissolution of the salt before sintering was found to enable easier interspersion of the two components, resulting in good connectivity of the beads via the formation of ‘‘windows＇ ＇ between the pores, and rapid elimination of salt from the structure. Porous Al with densities in the range of 0.28–0.86 g/cm3 exhibited compressive yield strengths in the range of 0.14 to 7.5 MPa, with no difference being observed between the samples made by this route and by more conventional dissolution of the salt after sintering. These novel steps widen the possibility for porous metal manufacture to other materials, not limited by the need to have a sintering temperature below that for the melting point of salt.