106 resultados para Siglo IV
Resumo:
Air-stable n-type field effect transistors were fabricated with an axially oxygen substituted metal phthalocyanine, tin (IV) phthalocyanine oxide (SnOPc), as active layers. The SnOPc thin films showed highly crystallinity on modified dielectric layer, and the electron field-effect mobility reached 0.44 cm(2) V-1 s(-1). After storage in air for 32 days, the mobility and on/off ratio did not obviously change. The above results also indicated that it is an effective approach of seeking n-type semiconductor by incorporating the appropriate metal connected with electron-withdrawing group into pi-pi conjugated system.
Resumo:
Phthalocyanato tin(IV) dichloride, an axially dichloriniated MPc, is an air-stable high performance n-type organic semiconductor with a field-effect electron mobility of up to 0.30 cm(2) V-1 s(-1). This high mobility together with good device stability and commercial availability makes it a most suitable n-type material for future organic thin-film transistor applications.
Resumo:
The extraction behavior of thorium(IV) sulfate by primary amine N1923 in imidazolium-based ionic liquid (IL) namely 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim]PF6) was systematically studied in this paper. Results showed that the extraction behavior was quite different from that using conventional solvent as diluent. A reversed micellar solubilization extraction mechanism was proposed for the extraction of thorium(IV) by N1923/[C(8)mim]PF6 via slope analysis method and polarized optical microscopy (POM)/transmission electron microscopy (TEM) observation. The salt-out agent, Na2SO4, was demonstrated to prompt this extraction mechanism.
Resumo:
Synergistic extraction and recovery of Cerium(IV) (Ce(IV)) and Fluorin (F) from sulfuric solutions using mixture of Cyanex 923 and di-2-ethylhexyl phosphoric acid (D2EHPA) in n-heptane have been carried out. in order to investigate the synergistic extraction of Cyanex 923 + D2EHPA, extraction Ce(IV), F, Ce(III) and Ce-F mixture solution using D2EHPA or Cyanex 923 as extractant alone were studied firstly, and then Synergistic extraction of Ce(IV), F and Ce(IV)-F mixture solution with D2EHPA + Cyanex 923 were carried out. The largest synergistic coefficient of Ce(IV) is obtained at the mole fraction X-Cyanex (923) = 0.8. The synergistic enhancement coefficients (R-max) obtained for Ce(IV) are 23.12 in Ce(IV) solution, and in Ce-F mixed solution R-max for Ce(IV) and F are 2.24 and 3.25 respectively.
Resumo:
The extraction behavior of Ce(IV) along with Th(IV) and Ln(III) (Ln = Ce, Gd, Yb) nitrate by pure ionic liquid, [C(8)mim]PF6, was investigated. [C(8)mim]PF6 alone showed good extraction ability for Ce(IV), while it was slight for Th(IV) and negligible for Ln(III). The extraction behavior of Ce(IV) by [C(8)mim]PF6 was particularly studied, and the most probable extraction mechanism proposed was the anion exchange mechanism. Moreover, the stripping of Ce(IV) from IL phase was also investigated. The Ce(IV) in IL phase can be quantitatively recovered by water.
Resumo:
Extraction kinetics of thorium(IV) with primary amine N1923 in sulfate media has been investigated by a constant interfacial cell with laminar flow. Studies of interfacial tension and effects of the stirring rate, temperature, and specific interfacial area on mass transfer rate show that the most probable reaction zone takes place at the liquid-liquid interface. According to the experimental data correlated as a function of the concentration of the relevant species involved in the extraction reaction, the rate equation of extracting thorium has been obtained as follows: -d[Th(IV)]((o))/dt = 10(-3.10)center dot[Th(IV)](0.89)center dot[(RNH3)(2)SO4](0.74).
Resumo:
The title compound, {[Mn(C10H28N6)][Sn3Se7]}(n), consists of anionic (infinity){[Sn3Se7](2-)} layers interspersed by [Mn(peha)](2+) complex cations ( peha is pentaethylenehexamine). Pseudo-cubic (Sn3Se4) cluster units within each layer are held together to form a 6(3) net with a hole size of 8.74 x 13.87 angstrom. Weak N-H center dot center dot center dot Se interactions between the host inorganic frameworks and metal complexes extend the components into a three-dimensional network. The incorporation of metal complexes into the flexible anion layer dictates the distortion of the holes.
Resumo:
Lead(IV) dioxide (PbO2) has been used as the electron injection layer (EIL) to realize high-efficiency inverted top-emitting organic light-emitting diodes (I-TOLEDs). It can be seen that the inserting of the PbO2 EIL significantly reduces operational voltage, thus greatly improving the current efficiency and power efficiency of fabricated I-TOLEDs. The 10-(2-benzothiazolyl)-1, 1, 7, 7-tetramethyl-2, 3, 6, 7-tetrahydro-1H, 5H, 11H-[1] benzopyrano [6, 7, 8-ij] quinolizin-11-one (C545T)-based I-TOLEDs with the PbO2 EIL exhibit a maximum current efficiency of 31.6 cd A(-1) and a maximum power efficiency of 14.3 lm W-1, which are both higher than 22.5 cd A(-1) and 5.4 lm W-1 of the I-TOLEDs with LiF as the EIL respectively. A detailed analysis with respect to the role mechanism of PbO2 in electron injection has been presented. The improvement in EL performance is attributed to the formation of the interfacial dipoles at the electrode interface due to charge transfer between PbO2 and Alq(3).
Resumo:
BACKGROUND: Ionic liquids (ILs) as environmentally benign solvents have been widely studied in the application of solvent extraction. However, few applications have been successfully industrialized because of the difficult stripping of metal ions or the loss of components of the ILs. More work needs to be done to investigate the extraction behaviour of IL-based extraction systems. In this work, the extraction behaviour of Ce(IV), Th(IV) and some trivalent rare earth (RE) nitrates by di(2-ethylhexyl) 2-ethylhexylphosphonate (DEHEHP) in the IL, 1-methyl-3-octylimidazolium hexafluorophosphate ([C(8)mim]PF6), was investigated and compared with that in the n-heptane system. In particular, the effect of F(I) on the extraction mechanism for Ce(IV) and its separation from Th(IV) was investigated. Otherwise, the recovery efficiency of Ce(IV) and F(I) from a practical bastnasite leach liquor was examined using IL based extraction.
Resumo:
BACKGROUND: Thermodynamic studies on Ce(IV) extraction with primary amine N1923 demonstrate that primary amine N1923 is an excellent extractant for separation of Ce(IV) from Re(III). In order to clarify the mechanism of extraction and to optimize the parameters in practical extraction systems used in the rare earth industry, the extraction kinetics was investigated using a constant interfacial area cell with laminar flow in the present work.RESULTS: The data indicate that the rate constant (k(ao).) becomes constant when stirring speed exceeds 250 rpm. The apparent forward extraction rate is calculated to be 10(-1.70). The activation energy (E.) was calculated to be 20.5 kJ/mol from the slope of log kao against 1000/T. The minimum bulk concentration of the extractant necessary to saturate the interface (C-min) is lower than 10(-5) mol L-1.CONCLUSION: Studies of interfacial tension and the effects of stirring rate and specific interfacial area on the extraction rate show that the extraction rate is kinetically controlled, and a mass transfer model has been proposed. The rate equation has been obtained as: -d[Ce(IV)]/dt = 10(-1.70)[Ce(IV)] [(RNH3)(2)SO4](1.376). The rate-controlling step has been evaluated from analysis of the experimental results.
Resumo:
The influences of additive, diluents, temperature, acidity of the aqueous phase on the interfacial behavior of primary amine N1923 in sulfate media have been investigated using the Du Nouy ring method. In addition, the effect of concentration of thorium(IV) loaded in the organic phase on the interfacial tension has also been studied. The interfacial tension isotherms are processed by matching different adsorption equations such as the Gibbs and the Szyszkowski. The surface excess at the saturated interface (Gamma (max)) and the minimum bulk concentration of the extractant necessary to saturate the interface (C-min) under different conditions are calculated according to two adsorption equations to be presented in comprehensive tables and figures. It appears that primary amine N1923 has strong interfacial activity and behaves very differently in various diluents systems. The surface excess at saturated interface increase with the type of diluerits in the following order: chloroform < aromatic hydrocarbons < aliphatic hydrocarbons. The relationship between the interfacial activity and kinetics of thorium extraction by primary amine N1923 has been discussed by considering different factors. However, the interfacial activity of primary amine N1923 is only a qualitative parameter suggesting the interfacial mechanism for thorium extraction, it cannot give strong evidence quantitatively supporting this mechanism.
Resumo:
A new polyoxometalate [Co(phen)(3)](2)[HPMo4V Mo-4(VI) V-6(IV) M2O44]center dot 4H(2)O (M = 0.78Mo(V)+ 0.22V(IV)) 1 was hydrothermally synthesized and characterized by IR, elemental analyses, X-ray photoelectron spectrum, ESR and single crystal X-ray diffraction. The title compound is in the triclinic space group P (1) over bar with a = 12.0953(7) angstrom, b = 14.0182(6) angstrom, c = 14.6468(7) angstrom, V=2402.55(18) angstrom(3), alpha = 105.134(2), beta = 91.841(3), gamma = 91.401(2), Z = 1, and R-1 (wR(2)) = 0.0617 (0.1701). The compound was prepared from tetra-capped pseudo-Kepin with phosphorus-centered polyoxoanions [PMo8V6M2O44](5-) , [Co(phen)(3)](2+) cations and linked through hydrogen bonds and pi-pi stacking interaction into three-dimensional supramolecular framework. Astudy of the magnetic properties of 1 demonstrates that it exhibits antiferromagnetic coupling interactions.