Energy transfer and tunable luminescence properties of Eu3+ in TbBO3 microspheres via a facile hydrothermal process

Tb(1-x)BO3:xEu(3+) (x = 0-1) microsphere phosphors have been successfully prepared by a simple hydrothermal process directly without further sintering treatment. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL), low-voltage cathodoluminescence (CL), and time-resolved emission spectra as well as lifetimes were used to characterize the samples.

Hydrothermal synthesis and luminescent properties of LuBO3: Tb3+ microflowers

Hexagonal vaterite-type LuBO3:Tb3+ microflower-like phosphors have been successfully prepared by an efficient surfactant- and template-free hydrothermal process directly without further sintering treatment. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometry transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence(PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples.

Failure of the plasma-sprayed coating of lanthanum hexaluminate

Lanthanum magnesium hexaluminate (LaMgAl11O19, LMA) is an attractive material for thermal barrier coatings (TBCs), and the failure of its coating was studied in this work by thermal cycling, X-ray diffraction, dilatometric measurement and thermal gravimetric-differential thermal analysis. The dilatometric measurement indicates that even though the bulk material of LMA has a higher sintering-resistance than the typical TBC material, i.e. yttria-stabilized zirconia (YSZ), the plasma sprayed coating of LMA has two serious contractions due to the re-crystallization of LMA and phase transitions of alumina.

Lanthanum zirconate ceramic toughened by BaTiO3 secondary phase

La2Zr2O7 (LZ) is a promising thermal barrier coating material for the high-temperature applications, which could be significantly toughened by the BaTiO3 piezoelectric phase incorporated into the matrix. The composites of xBaTiO(3)/(l-x)LZ (x=5, 10, 15, 20 vol%, LZ-x-BaTiO3) were densified by means of high-pressure sintering (HPS) under a pressure of 4.5 GPa at 1450 degrees C for 10 min, by which a high relative density above 93% could be obtained.

Silica Materials Doped with Bifunctional Ionic Liquid Extractant for Yttrium Extraction

Two new silica-based organic-inorganic hybrid materials (B104SGs and O104SGs) doped with a binary mixture of imidazolium and phosphonium ionic liquids have been synthesized and used as sorbents in batch system for rare earths (RE) separation. Imidazolium ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate (C(4)mim(+)PF(6)(-)) or 1-octyl-3-methylimidazolium hexafluorophosphate (C(8)mim(+)PF(6)(-)) acted as porogens to prepare porous materials and additives to stabilize extractant within silica gel.

Promoting carbonization of polypropylene during combustion through synergistic catalysis of a trace of halogenated compounds and Ni2O3 for improving flame retardancy

The effect of combination between a trace of halogenated compounds (such as ferric chloride and ammonium bromide) and Ni2O3 particles on the carbonization of polypropylene (PP) was investigated during combustion. The results showed a synergistic catalysis of combined halogenated compounds with Ni2O3 in promoting the formation of the residual char during combustion. The investigation on the promotion mechanism showed that halide radical releasing from halogen-containing additives worked as a catalyst to accelerate dehydrogenation-aromatization of degradation products of PR which promote the degradation products to form the residual char catalyzed by nickel catalyst.

High-pressure sintered yttria stabilized zirconia ceramics

Fast densification of 8YSZ ceramics under a high pressure of 4.5 GPa was carried out at different temperatures (800, 1000, 1450 degrees C), by which a high relative density above 92% could be obtained. FT-Raman spectra indicate that the 8YSZ underwent a phase transition from partially tetragonal to partially cubic phase as temperatures increase from 1000 to 1450 degrees C when sintering under high pressure. The electrical properties of the samples under different high-pressure sintering conditions were measured by complex impedance method. The total conductivity of 0.92 x 10(-2) S cm(-1) at 800 degrees C has been obtained for 8YSZ under high pressure at 1450 degrees C, which is about 200 degrees C lower than that of the samples prepared by conventional pressureless sintering.

Effects of Y2O3 addition on the phase evolution and thermophysical properties of lanthanum zirconate

Lanthanum zirconate (La2Zr2O7, LZ) powders with the addition of various Y2O3 contents for potential thermal barrier coatings (TBCs) application were synthesized by solid-state reaction. The structure evolution, sintering-resistance and thermophysical properties of the synthesized powders and sintered ceramics were systematically studied. X-ray diffraction (XRD) results indicate that LZ containing 3-12 wt.% Y2O3 mainly keeps a pyrochlore-type structure, and two new phases of LaYO3 and Y0.18Zr0.82O1.91 are also detected. Raman spectra confirm that the higher the Y2O3 content, the easier is the formation of LaYO3.

Investigation of the dewetting inhibition mechanism of thin polymer films

The mechanism of inhibition of polymer film dewetting is investigated by adding a star comb-like polymer, four-arm P(S-ran-VB-g-PMMA), to PS film and PMMA film on different substrates. It is found that the mechanism of inhibition of polymer film dewetting is kinetic in nature, and is related to the miscibility between the additional compound and the polymer film. On addition to the miscible system [four-arm P(S-ran-VB-g-PMMA) and PMMA], the star comb-like polymers can increase the resistant force of dewetting with hole growth and inhibit the dewetting process of the thin polymer film by enrichment in the rim.

Enhanced luminescence of BPO4 by mixing with SiO2 and Al2O3

In this paper, BPO4-xSiO(2) (X: SiO2/BPO4 molar ratio, 0-70%) and BPO4-xAl(2)O(3) (X: Al2O3/BPO4 molar ratio, 0-20%) powder samples were prepared by the Pechini-type sol-gel (PSG) process using glycerol and poly(ethylene glycol) as additives. The structure and optical properties of the resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), diffuse reflection spectra, photoluminescence (PL) excitation and emission spectra, kinetic decay, and X-ray photoelectron spectra (XPS), respectively. It was found that the Pechini-type sol-gel-derived BPO4-xSiO(2) annealed at 1000 degrees C and BPO4-xAl(2)O(3) annealed at 960 degrees C exhibited bright bluish-white emissions centered at 428 and 413 nm, respectively. The luminescence decay curve analysis indicates that each sample has two kinds of lifetimes (more than 0.4 ms and less than 10 ns) and two types of kinetic decay behaviors, which can be fitted into a double-exponential function and a single-exponential function, respectively.

Shape-controllable synthesis and upconversion properties of lutetium fluoride (doped with Yb3+/Er3+) microcrystals by hydrothermal process

Lutetium fluorides with different compositions, crystal phases, and morphologies, such as beta-NaLuF4 hexagonal microprisms, microdisks, mirotubes, alpha-NaLuF4 submicrospheres, LuF3 octahedra, and NH4Lu2F7 icosahedra, prolate ellipsoids and spherical particles have been successfully synthesized via a facile hydrothermal route. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction, and photoluminescence spectra were used to characterize the samples. The intrinsic structural feature of lutetium fluorides, the solution pH values, F- sources, and organic additives (Cit(3-) and EDTA) account for the ultimate shape evolutions of the final products. The possible formation mechanisms for products with various architectures have been presented. Additionally, we investigated the upconversion luminescence properties of beta-NaLuF4: 20% Yb3+/2% Er3+ with different morphologies.

Successful establishment of MEKC with electrochemiluminescence detection based on one functionalized ionic liquid

Herein, one water-soluble functionalized ionic liquid, 1-butyl-3-methylimidazolium dodecyl sulfate ([BMIm(+)][C12H25SO4-]), was designed and its superiorities either used as supporting electrolytes or as additives for successful establishment of MEKC with electrochemiluminescence (ECL) detection (MEKC-ECL) method were investigated. Compared with the common supporting electrolytes such as phosphate solution, 1-butyl-3-methylimidazolium dodecyl sulfate solution used as running buffers led to greatly enhanced ECL intensities and column efficiencies for negative targets, a little increase for neutral-charge ones while maintained nearly unchanged for positive ones due to the electrostatic forces between the large cation BMIm(+) and the solutes and the hydrophobic interactions resulting from the large anion C12H25SO4.

Cyclization of citronellal to p-menthane-3,8-diols in water and carbon dioxide

A clean process has been developed for the synthesis of p-menthane-3,8-diols from cyclization of citronellal in CO2-H2O medium without any additives. With the addition of CO2, the reaction rate could be enhanced about 6 times for the cyclization of citronellal in H2O, because CO2 dissolved into water and formed carbonic acid inducing an increase of the acidity. Although, the reaction conversion in CO2-H2O is slightly lower compared to that obtained with sulfuric acid as catalyst, CO2-H2O could replace the sulfuric acid at a relative higher reaction temperature. The reaction kinetics studies showed that the hydration of isopulegols to p-menthane-3,8-diols is a reversible reaction. The equilibrium constant and the maximum equilibrium yield obtained in CO2-H2O at a range of CO2 pressures are similar to that with sulfuric acid catalyst.

Microstructure, thermal stability and mechanical properties of the novel (W1-xAlx)C-Co (x=0.2, 0.33, 0.4, 0.5) cemented carbide

Bulk novel cemented carbides (W1-xAlx)C-10.1 vol% Co (x = 0.2, 0.33, 0.4, 0.5) are prepared by mechanical alloying and hot-pressing sintering. Hot-pressing (HP) is used to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have good mechanical properties compared with WC-Co. The density and operating cost of the novel material is much lower than a WC-Co system. The material is easy to process and the processing leads to nano-scaled, rounded, particles in the bulk material. The hardness of (W1-xAlx)C-10.1 vol% Co (x = 0.2, 0.33, 0.4, 0.5) hard material is 20.37, 21.16, 21.59 and 22.16 GPa, and the bending strength is 1257, 1238, 1211 and 1293 MPa, with the aluminum content varying from 20% to 50%. The relationship between the microstructure and the mechanical properties of the novel hard alloy is also discussed.

Influence of isooctanol on the interfacial activity and mass transfer of ytterbium(III) using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an acidic extractant

BACKGROUND: Introducing an adduct into an extractant system is an effective method of improving extraction performance. The effect of additives upon extraction is very important, especially in the case of interfacial behaviour. In most work published in the literature, there is little data on the interfacial behaviour of extractants and modifiers. As the mass transfer must pass through an interface, the influence of isooctanol on the interfacial activity and mass transfer of ytterbium(III) using 2-ethylhexylphosphonic acid mono-2-ethlhexyl ester has been investigated.RESULTS: With increasing amounts of isooctanol, the interfacial tension and surface excess (Gamma(max)) of the 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester(HEHEHP)-isooctanol system decreased, and the area of the absorbed HEHEHP molecule (Amin) increased. The interfacial activity of the HEHEHP-isooctanol system varied significantly depending on ionic strength and temperature and the mass transfer flux decreased with increasing isooctanol content.