Synthesis of gold nanoplates by aspartate reduction of gold chloride

Single crystal nanoplates with thickness less than 30 nm, characterized by hexagonal and truncated triangular shapes bounded mainly by {111} facets, were obtained in large quantities by aspartate reduction of gold chloride.

mer-(4-aminobenzenesulfonato-kappa N)triapua(1,10-phenanthroline-kappa N-2,N ')cobalt(II) chloride

Both coordination and hydrogen bonds contribute to networking in the supramolecular title compound, [Co(C6H6NO3S)(C12H8N2)(H2O)(3)]Cl, which contains a discrete [Co(C6H6NO3S)(C12H8N2)(H2O)(3)](+) complex cation, formed by one 4-aminobenzenesulfonate ligand, one 1,10-phenanthroline ligand and three coordinated water molecules, together with one uncoordinated chloride anion. These discrete cations and chloride anions are connected by hydrogen-bonding interactions into a two-dimensional supramolecular motif. Further hydrogen-bonding interactions consolidate the structural architecture and extend the two-dimensional supramolecular structure into a three-dimensional network.

Density-functional study of lanthanum, ytterbium, and lutetium dimers

La-2, Yb-2, and Lu-2 have been studied by use of the density-functional methods B3LYP, BLYP, B3PW91, BHLYP, BP86, B3P86, MPW1PW91, and PBE1PBE. In these density-functional methods, the exchange functional is from either Becke's three-parameter HF-DFT hybrid exchange functional (B3), pure DFT exchange functional of 1988 (B), a modification of the half-and-half HF/DFT hybrid method (BH), Perdew-Wang 1991 (PW91), or Barone's modified PW91 (MPW1), while the correlation functional is from either Lee, Yang, and Parr (LYP), Perdew-Wang 1991 (PW91), or Perdew 86 (P86). PBE1PBE is the generalized-gradient-approximation exchange-correlation functional of Perdew, Burke, and Ernzerhof. For La-2, the calculated bond distance is in reasonable agreement with the experiment, but the calculated vibrational frequency is underestimated significantly compared with the experiment. Only BP86 and B3P86 have the best performance in reproducing the experimental dissociation energy for La-2. For the van der Waals dimer Yb-2, three functionals, B3LYP, BLYP, and BHLYP have excellent performance in reproducing the spectroscopic constants compared with both the experiment and previous theoretical studies.

The influence of core-shell structured modifiers on the toughness of poly (vinyl chloride)

The core-shell structured grafted copolymer particles of polybutadiene grafted polymethyl methacrylate (PB-g-PMMA, MB) were prepared by emulsion polymerization. The MB particles were used to modify poly (vinyl chloride) (PVC) by melt blending. The mechanical properties of the PVC blends were investigated. The micro-morphology of the PVC blends was observed by scanning electron microscopy (SEM). The results indicated that the samples with the best impact strength could be obtained when the core-shell weight ratio of PB to PMMA is lower than 93:7, the mechanical properties correlated well with SEM morphologies, the addition of modifier with the ratio core to shell of 93:7 could reduce the domain size of the dispersed phase. Furthermore, the compatibility and properties of the blends were greatly enhanced and improved. The modifier particles could be well dispersed in the PVC matrix.

Solvent extraction of scandium(III), yttrium(III), lanthanum(III) and gadolinium(III) using Cyanex 302 in heptane from hydrochloric acid solutions

The extractions of the selected rare earths (Sc, Y, La and Gd) from hydrochloric acid solutions have been investigated using bis(2,4,4-trimethylpentyl)-mono thiophosphinic acid (Cyanex 302, HL) in heptane as an extractant. The results demonstrate that the extractions of rare earths occur via the following reaction: Sc(OH)(2+) + 2[(HL)(2)]((O)) double left right arrow [Sc(OH)L-2 (.) 2(HL)]((O)) + 2H(+) Y3+ + 3[(HL)(2)]((O)) double left right arrow [Y(HL2)(3)]((O)) + 3H(+) La(OH)(2)(+) + 3[(HL)(2)](O) double left right arrow [La(OH)(2)L (.) 5(HL)]((O)) + H+ Gd(OH)(2+) + 3[(HL)(2)]((O)) double left right arrow [Gd(OH)L-2 (.) 4(HL)]((O)) + 2H(+) The pH(1/2) values and equilibrium constants of the extracted complexes have been deduced by taking into account the aqueous phase complexation of the metal ion with hydroxyl ligands and plausible complexes extracted into the organic phase. According to the pH(1/2) values, it is possible to realize mutual separation among Sc(III), Y(III), La(III) and Gd(III) with Cyanex 302 by controlling aqueous acidity.

On improving the phase stability and thermal expansion coefficients of lanthanum cerium oxide solid solutions

The phase stability of lanthanum cerium oxide (La2Ce2O7), which is stable up to 1400 degrees C, and the thermal expansion coefficient of La2Ce2O7 doped with Ta2O5 or WO3 were studied. The thermal expansion coefficient of La2Ce2O7 below 400 degrees C was increased by adding more CeO2 or doping with either Ta2O5 or WO3.

Independence of the brittle-ductile transition from the rubber particle size for impact-modified poly(vinyl chloride)

A series of acrylic impact modifiers (AIMS) with different particle sizes ranging from 55.2 to 927.0 nm were synthesized by seeded emulsion polymerization, and the effect of the particle size on the brittle-ductile transition of impact-modified poly(vinyl chloride) (PVC) was investigated. For each AIM, a series of PVC/AIM blends with compositions of 6, 8, 10, 12, and 15 phr AIM in 100 phr PVC were prepared, and the Izod impact strengths of these blends were tested at 23 degrees C. For AIMs with particle sizes of 55.2, 59.8, 125.2, 243.2, and 341.1 nm, the blends fractured in the brittle mode when the concentration of AIM was lower than 10 phr, whereas the blends showed ductile fracture when the AIM concentration reached 10 phr. It was concluded that the brittle-ductile transition of the PVC/AIM blends was independent of the particle size in the range of 55.2-341.1 nm. When the particle size was greater than 341.1 nm, however, the brittle-ductile transition shifted to a higher AIM concentration with an increase in the particle size. Furthermore, the critical interparticle distance was found not to be the criterion of the brittle-ductile transition for the PVC/AIM blends.

The thermal cycling behavior of Lanthanum-Cerium Oxide thermal barrier coating prepared by EB-PVD

Bulk material and coatings of Lanthanum-Cerium Oxide (La2Ce2O7) with a fluorite structure were studied as a candidate material for thermal barrier coating (TBC). It has been showed that such material has the properties of low thermal conductivity about four times lower than YSZ, the difference in the thermal expansion coefficient between La2Ce2O7 and bond coat is smaller than that of YSZ in TBC systems, high phase stability between room temperature and 1673 K, about 300 K higher than that of the YSZ. The coating prepared by electron beam physical vapor deposition (EB-PVD) showed that it has good thermal cycling behavior, implying that Such material can be a promising thermal barrier coating material. The deviation of coating composition from ingot can be overcome by the addition of excess La2O3 during ingot preparation and/or by adjusting the process parameters.

Facile preparation of ZnTiO3 ceramic powders in sodium/potassium chloride melts

A facile molten salt synthesis route was developed to prepare ZnTiO3 ceramic powders with simple oxides ZnO and TiO2 using sodium and potassium chloride eutectic salts as flux. The role of calcination temperature and time and the amount of salt addition to ZnTiO3 formation was investigated by thermogravimetry-differential thermal analysis, X-ray diffraction and Fourier transformation-infrared spectroscopy measurements. Pure hexagonal phase of ZnTiO3 could be obtained from the mixture of the simple oxides and the chlorides (50 mol% KCl, 20 times to oxides in molar ratio) heating at 800 degrees C for 6 h. The scanning electron microscopy images revealed the products were hexagonal sheets of about 1-3 mu m size. Increasing the amount of salt aids in reducing the crystal sizes of final ceramic powders because of diluting the solution.

Lanthanum zirconate nanofibers with high sintering-resistance

The PVP/lanthanum nitrate/zirconium oxychloride (PVP-precursor) nanofiber was prepared by electrospinning technique. Lanthanum zirconate (La2Zr2O7, LZ) in the nanofiber is formed after calcination at 800 degrees C and the nanofiber with pyrochlore structure and a diameter of 100-500 nm can be obtained by calcination of the above precursor fiber at 1000 degrees C for 12 h. The surface of the fiber is rough but the continuous microstructure is still maintained after calcination. LZ fibers stack randomly, resulting in a structure with a low contact area between the fibers. This special structure makes the fiber to have a high resistance to sintering at elevated temperatures. The BET (Brunauer-Emmett-Teller) specific surface areas of the LZ fiber and powder calcined at different temperatures are shown in this paper, and the fiber was characterized by TG-DTA (thermal gravimetry-differential thermal analysis), XRD (X-ray diffraction), N-2 absorption-desorption porosimetry and SEM (scanning electron microscopy).

Synergistic extraction of rare earths(III) from chloride medium with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 and di-(2-ethylhexyl)-2-ethylhexylphosphonate

The synergistic effect of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 (HPMBP, HA) and di-(2ethylhexyl)-2-ethylhexylphosphonate (DEHEHP, B) in the extraction of rare earths (RE) from chloride solutions has been investigated. Under the experimental conditions used, there was no detectable extraction when DEHEHP was used as a single extractant while the amount of RE(III) extracted by HPMBP alone was also low. But mixtures of the two extractants at a certain ratio had very high extractability for all the RE (III). For example, the synergistic enhancement coefficient was calculated to be 9.35 for Y3+, and taking Yb3+ and Y3+ as examples, RE3+ is extracted as RE(OH)A(2).B. The stoichiometry, extraction constants and thermodynamic functions such as Gibbs free energy change Delta G (-17.06kJmol(-1)), enthalpy change Delta H (-35.08kjmol(-1)) and entropy change Delta S (-60.47JK(-1)mol(-1)) for Y3+ at 298 K were determined. The separation factors (SF) for adjacent pairs of rare earths were calculated. Studies show that the binary extraction system not only enhances the extraction efficiency of RE(III) but also improves the selectivity, especially between La(III) and the other rare earth elements.

Synthesis of substituted indenyl lanthanide chloride and molecular structure of [(C5H9C9H6)(2)Yb(mu-Cl)(2)Li(Et2O)(2)]

Reaction of anhydrous ytterbium trichlorides with 2 equiv. of cyclopentylindenyl lithium in THF solution, followed by removal of the solvent MO. crystallization of the product from diethyl ether, affords a crystal complex of the composition (C5H9C9H6)(2)Yb(mu-Cl)(2)Li(Et2O)(2). Crystallographic analysis shows that the ytterbium coordinated by two cyclopentylindenyl rings and lithium surrounded by two ether molecules are bridged by the two chlorine atoms and Yb, U and two chlorine atoms form a plane.

Separation of scandium, yttrium and lanthanum in high-performance centrifugal partition chromatography with S-octyl phenyloxy acetic acid

Separation of scandium(III), yttrium(III) and lanthanum(III) was performed by high-performance centrifugal partition chromatography (HPCPC) employing the stationary phase of S-octyl phenyloxy acetic acid (CA-12). The liquid-liquid extraction behavior of CA-12 for Sc(III), Y(III) and La(III), the acidity of aqueous phase, and the operation conditions of HPCPC were examined. The retention volume (V-R) increased with the order of Y(III), La(III) and Sc(III) accompanied with the elution of the mobile phase in different pH, which is lowered from 4.6 to 2.1.