Hydrothermal synthesis of SrCO3 : Eu3+/Tb3+ microneedles and their luminescence properties

SrCO3:Eu3+ /Tb3+ microneedles that grow along the a-axis were successfully prepared through a large-scale and facile hydrothermal method without any template and further annealing treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra as well kinetic decays, were used to characterize the samples. The preferential growth along a-axis for SrCO3:Eu3+/Tb3+ microneedles has been proposed through analysis of the XRD patterns of samples obtained at different hydrothermal treatment time. Under ultraviolet excitation, the SrCO3:Eu3+ and SrCO3:Tb3+ microncedle samples show a strong red and green emission corresponding to the D-5(0)-F-7(j) (J = 1, 2, 3, 4) transitions of Eu3+ and the D-5(4)-(7) F-j (J = 6, 5, 4, 3) transitions of Tb3+, respectively, which have potential applications in lighting fields.

An effective hydrothermal route for the synthesis of multiple PDDA-protected noble-metal nanostructures

In this Article, we demonstrate an effective hydrothermal route for the synthesis of multiple PDDA-protected (PDDA = poly(diallyl dimethylammonium) chloride) noble-metal (including silver, platinum, palladium, and gold) nanostructures in the absence of any seeds and surfactants, in which PDDA, an ordinary and water-soluble polyelectrolyte, acts as both a reducing and a stabilizing agent. Under optimal experimental conditions, Ag nanocubes, Pt and Pd nanopolyhedrons, and Au nanoplates can be obtained, which were characterized by transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. More importantly, the nanostrucfures synthesized show potential applications in surface-enhanced Raman scattering and electrocatalysis, in which Ag nanocubes and Pt nanopolyhedrons were chosen as the examples, respectively.

Rapid synthesis of hexagon-shaped gold nanoplates by microwave assistant method

The microwave (MW)-based thermal process was applied to the preparation of hexagon-shaped gold nanoplates. The fort-nation of gold nanoplates occurs rapidly in a single step, carried out by directly heating a reaction mixture of HAuCl4 with sodium citrate in an MW reactor. And the gold nanoplates were characterized by UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The experimental results indicated that the sizes and morphologies of the gold nanomaterials strongly depend both on the heating methods and molar ratio of HAuCl4 to sodium citrate in the initial reaction mixture. At the molar ratio 5 : 4 (HAuCl4 to sodium citrate), hexagonal nanoplates with large Au (111) crystallographic facet were preferentially synthesized by the MW assistant method.

Hydrothermal synthesis of spherical and hollow Gd2O3 : Eu3+ phosphors

Spherical and submicrometer-sized hollow Gd2O3:Eu3+ phosphors were prepared by homogeneous precipitation and hydrothermal method by varying the concentrations of reactants and changing the synthesis conditions. In the precipitation step, the spherical nucleus was formed and grew to large particles. In the hydrothermal step, the large particles crystallized to solid or hollow spheres. At last, Gd2O3:Eu3+ phosphors were obtained by annealing at the temperature more than 600 degrees C. The deduced mechanics of forming the solid and hollow spheres was proposed. And the obtained spherical Gd2O3:Eu3+ phosphors had better red luminescence properties. The relative luminescence intensity and the lifetime increased with increasing annealing temperatures.

The magnetic and structural properties of hydrothermal-synthesized single-crystal Sn1-xFexO2 nanograins

The crystal structure and magnetic properties of Sn1-xFexO2 nanograins synthesized by simple hydrothermal method using SnCl4 center dot 5H(2)O and FeCl3 center dot 6H(2)O as raw materials are studied. No secondary phase was found in the XRD spectrum. The linear change of lattice volume for different Fe content strongly supports that the Fe3+ substitutes Sn4+ in SnO2 lattice. A Raman and IR spectra study indicated that the Fe incorporates into the SnO2 lattice. Both ferromagnetic and paramagnetic signals are detected in the Mossbauer spectra. The Sn1-xFexO2 (x <= 0.10) samples show room-temperature ferromagnetism (RTFM) and the saturation magnetization increased with increasing Fe percent. Fe ions present three kinds of magnetic behaviors including paramagnetic, ferromagnetic, and antiferromagnetic in the samples observed by investigation of the M-H and M-T curves. The weak RTFM was due to only a fraction of Fe ions contributing to magnetic-order coupling mediated by oxygen vacancy.

Hydrothermal synthesis of Fe and Mn doped SnO2 and its magnetic structures

The dilute magnetic semiconductor of Sn1-x-yMnxFeyO2 (0 <= x <= 0.10, 0 <= y <= 0.10) Were syhthesized with the hydrothermal method using SnCl4, Mn(CH3COO)(2) center dot 4H(2)O and FeCl3 center dot 6H(2)O as the raw materials. The structure, morphologies and magnetic properties of the sample were characterized via X-ray powder diffractometer(XRD), transmission electron microscopy(TEM), Raman spectrum and superconducting and quantum interference device(SQUIT), and Mossbeaur spectrum. No secondary phase was found in the XRD spectrum. The morphology of the samples is affected by the kind or the mount of transition metal. The local vibrating model-of Mn Positioned SnO2 sites was found in Raman spectrum. The measured magnetic results indicate that when x = 0.10, y = 0, the sample exhibits strong magnetization in low-temperature (5 K), but the magnetization decrease rapidly at room. temperature; In contrast, when x = 0, y = 0.1, the sample's magnetization and coercivity are both small, but being temperature independent. Mossbeaur spectra indicates that part of the Fe is ferromagnetic coupled, and the simulating results indicate that the ferromagnetic character is intrinsic.

Hydrothermal synthesis, structure characterization of a new mixed Mo/V metal-oxygen cluster compound: [Co(phen)(3)](2)[HPMo4V (Mo4V6IV)-V-VI M2O44]center dot 4H(2)O, (M=0.78Mo(V)+0.22V(IV))

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.

Hydrothermal synthesis of ZrW2O8 nanorods

Negative thermal expansion ZrW2O8 nanorods were synthesized by a rapid low-temperature hydrothermal route, followed with a heat treatment at 500 degrees C for 6h. Acidity of the HCl addition to the mixed solution in the hydrothermal condition strongly affects the formation of the precursor ZrW2O7(OH)(2)(H2O)(2). High acidity of HCl in the range of 5-10 N facilitates the nucleation of ZrW2O7(OH)(2)(H2O)(2), but constrains its growth. Low acidity of HCl addition (< 5 N) only obtained the products ZrO2 and WO3 by firing the precursors. FE-SEM images revealed that the shape and size of ZrW2O8 were modeled after its precursor ZrW2O7(OH)(2)(H2O)(2).

The first discrete mixed-valence hexadecavanadate host shell cluster anions: hydrothermal synthesis, structure and characterization of [V16O38(Cl)](8-)

A new compound, [NH4](2)[Zn(phen)(3)](2)[Zn(phen)(2)(H2O)(2)][V16O38(Cl)] (.) 5H(2)O (1), was synthesized in the hydrothermal condition. The "naked" [V16O38(Cl)](8-) is the first observation with host shell structure in polyoxovanadate chemistry.

Hydrothermal synthesis and crystal structure of a sulfur-bridged binuclear copper(II) coordination polymer generated by a spontaneous reduction

A simultaneous reduction SO42- to S2- by 2,5-pyridinedicarboxylate under hydrothermal conditions produced a new binuclear copper(II) coordination polymer [CuS(4,4'-bipy)](n) (4,4-bipy = 4,4'-bipyridine) (1). Single crystal X-ray analysis revealed that compound I consisted of sulfur-bridged binuclear copper(II) units with Cu-Cu bonding which were combined with 4,4-bipy to generate a three-dimensional network constructed from mutual interpenetration of two-dimensional (6,3) nets. Crystal data for 1:C10H8CuN2S, tetragonal 14(1)/acd, a = 14.0686(5) Angstrom, b = 14.0686(5) Angstrom, c = 38.759(2) Angstrom, Z = 32. Other characterizations by elemental analysis, IR, EPR and TGA analysis were also described in this paper.

Microwave-assisted synthesis of high-molecular-weight poly(ether imide)s by phase-transfer catalysis

A facile and rapid polycondensation reaction of disodium bisphenol A with bis(chlorophthalimide)s was preformed with a domestic microwave oven in o-dichlorobenzene by phase-transfer catalysis. The polymerization reactions, in comparison with conventional heating polycondensation, proceeded rapidly and were completed within 25 min. The polymerizations gave the corresponding poly(ether imide)s with inherent viscosities of 0.55-0.92 dL g(-1). The effects of various factors on the polymerization, such as the amount of the catalyst, the reaction time, and the microwave power were studied. The properties of the polymers were briefly characterized.

Vaterite-type YBO3 : Eu3+ crystals: hydrothermal synthesis, morphology and photoluminescence properties

Vaterite-type YBO3:Eu3+ crystals with interesting flower and hedgehog fungus-like structures composed of nanosheets were obtained by controlled crystallization of Y2O3 and Eu2O3 in H3BO3 solutions under acidic hydrothermal (HT) conditions. Nanosheets of uniform thicknesses were formed by preferential crystal growth along the (100) crystallographic plane and specific three-dimensional structures were further developed through a homocentric growth mechanism. Optical emission measurements showed that the HT-grown nanosheet crystals exhibited a higher ratio of the emitted red-to-orange light ratio than crystals grown from solid-state reactions. The photoluminescence intensity and emission lifetimes were also studied as a function of the Eu3+ dopant concentration and the HT synthesis temperature. The effect of some additives: a chelating ligand, a surfactant and a polymer, on the YBO3:Eu3+ crystals morphology was also investigated.

Engineering white light-emitting Eu-doped ZnO urchins by biopolymer-assisted hydrothermal method

With the presence of biopolymer-sodium alginate as additive, Eu-doped ZnO (zinc oxide) urchins consisting of nanorods were synthesized through a hydrothermal route. X-ray diffraction pattern makes evident the absence of phase other than wurtzite ZnO. Upon excited by 325 nm xenon laser, such nanostructured Eu-doped ZnO urchins emit white light, which originates from the luminescence of ZnO and the intra-4f transitions of Eu3+ ions. Besides acting as stabilizing agent, sodium alginate may also sensitize the Eu3+ ions in the nanostructures and facilitate the energy transfer from the host to Eu3+ ions. (c) 2006 American Institute of Physics.