Luminescence properties of rare earth ions in cadmium metasilicate

The luminescence properties of CdSio(3):RE3+ phosphors doped with various rare earth ions are reported. The series of rare earth ions doped CdSiO3 phosphors are prepared by the conventional high-temperature solid-state method, and characterized by XRD and photoluminescence (PL) spectra. The results of XRD measurement indicate that the products fired under 1050 degreesC for 3 h have a good crystallization without any detectable amount of impure phase. The PL spectra measurement results show that CdSiO3 is a novel self-activated luminescent matrix. When rare earth ions such as Y3+, La3+, Gds(3+), Lus(3+), Ce3+, Nd3+, Ho3+, Era(3+), Tm3+ and Yb3+ are introduced into the CdSi03 host, one broadband centered at about 420 nm resulted from traps can be observed. In the case of other earth ions which show emissions at the visible spectrum region, such as Pr3+, Sm3+, Eu3+, Tb3+ and Dy3+, the mixture of their characteristic line emissions with the similar to 420 nm strong broadband luminescence results in various emitting colors. As a consequence, different emitting colors can be attairied via introducing certain appropriate active ions into the CdSiO3 matrix. In additional, this kind of phosphors shows good long-lasting properties when excited by UV light. All the results show that CdSiO3 is a potential luminance matrix.

Triboluminescence of a new europate complex

A new europium (III) complex Eu(HFNH)(3)Phen (HFNH: 4, 4, 5, 5, 6, 6, 6-heptafluoro-1-(2-naphthyl) hexane-1,3-dione; phen: 1, 10-phenanthroline) was synthesized and its triboltuninescent phenomenon was observed. Photoluminescence and triboluminescence spectra were successfully determined. The most intense triboluminescent emission originates front the transition of the, central Eu3+ ion from D-5(0) level to F-7(2) level. The triboluminescent spectrum is basically similar to that of photoluminescence, which correlates with the disorders of F atoms.

Extraction mechanism of La3+ from hydrochloric acid solution using Cyanex 302

The solvent extraction of La3+ from hydrochloric acid solutions was investigated using his (2, 4, 4-trimethylpentyl) monothiophosphinic acid (Cyanex 302, HL) as an extractant. The effect of equilibrium of aqueous acidity on extraction of La3+ using Cyanex 302 In different diluents was discussed. The effects of extractant concentration and chloride ion on the extraction reaction were also studied. Stoichiometry of the extraction reactions and the nature of metal complexes formed were determined using slope analysis technique and IR measurement.

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.

Formation equilibria of ternary metal complexes with citric acid and glutamine (alanine) in aqueous solution

The species and their formation constants in the ternary, systems were obtained by the Scogs2 software from potentiometric titration data. The Comics software was used to calculate the distribution of species in the ternary systems. MLXH, MLXH2 and MLXH3 are the common species in these systems. The coordination behaviors of the rare earths are very similar and their stability is closely matched. The ternary rare earth complexes are more stable than the corresponding ternary complexes of calcium. The ternary zinc complex with glutamine as the secondary ligand is more stable than the corresponding complexes of rare earths, but the ternary complex with alanine as the secondary ligand shows an inverse trend. The distributions of species in the ternary systems vary with pH changing. A prediction can be made that exogenous rare earths can affect the species of Ca and Zn in human body.

Luminescence and energy transfer properties of Ca2Gd8(SiO4)(6)O-2 : A(A = Pb2+, Tm3+) phosphors

Ca2Gd8(SiO4)(6)O-2: A(A = Ph2+, Tm3+) phosphors were prepared through the sol-gel process. X-ray diffraction (XRD), scanning electron microseopy(SEM) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 degreesC. SEM study reveals that the average grain size is 300 similar to 1000 nm. In Ca2Gd8(SiO4)(6)O-2: Tm3+ phosphors, the Tm3+ shows its characteristic blue emission at 456 nm (D-1(2)-F-3(4)) upon excitation into its H-3(6)-D-1(2)(361 nm), with an optimum doping concentration of 1 mol% of Gd3+ in the host lattices. In Ca2Gd8(SiO4)(6)O-2: Pb2+, Tm3+ phosphors, excitation into the Ph2+ at 266 nm (S-1(0)-P-3(1)) yields the emissions of Gd3+ at 311 nm (P-6-S-8) and Tm3+ at 367 nm (D-1(2)-H-3(6)) and 456 our (D-1(2)-F-3(4)), indicating that energy transfer processes of Pb2+-Gd3+ and Ph2+-Tm3+ have occur-red in the host lattices.

Sol-Gel Preparation of Zn2 Si04：Mn Phosphor Layers on Silica Spheres and Their Luminescent Properties

The synthesis and luminescence properties of Zn2SiO4:Mn phosphor layers on spherical silica spheres,i.e.,a kind of core-shell complex phosphor,Zn2SiO4:Mn@SiO2 were described.Firstly,monodisperse silica spheres were obtained via the Stober method by the hydrolysis of tetraethoxysilane(TEOS)Si(OC2H5)4 under base condition (using NH4OH as the catalyst).Secondly,the silica spheres were coated with a Zn2SiO4:Mn phosphor layer by a Pechini sol-gel process.X-ray diffraction(XRD),scanning electron microscope(SEM),energy-dispersive X-ray spectrum(EDS) and photoluminescence(PL) were employed to characterize the resulting complex phosphor.The results comfirm that 1000℃ annealed sample consists of crystalline Zn2SiO4:Mn shells and amorphous SiO2 cores.The phosphor show the green emission of Mn2+ at 521nm corresponding 4T1(4G)-6A1(6S) transition,and the possible luminescence mechanism is proposed.

Specific determination of As(V) by an acid phosphatase-polyphenol oxidase biosensor

An original amperometric biosensor based on the simultaneous entrapment of acid phosphatase (AcP) and polyphenol oxidase (PPO) into anionic clays (layered double hydroxides) was developed for the specific detection of As(V). The functioning principle of the bienzyme electrode consisted of the successive hydrolysis of phenyl phosphate into phenol by AcP, followed by the oxidation of phenol into o-quinone by PPO. The phenyl phosphate concentration was, thus, monitored by potentiostating the biosensor at -0.2 V vs Ag/AgCl to detect amperometrically the generated quinone. The detection of As(V) was based on its inhibitory effect on AcP activity toward the hydrolysis of phenyl phosphate into phenol. The As(V) can be specifically determined in pH 6.0 acetate buffer without any interferences of As(III) or phosphate, the detection limit being 2 nM or 0.15 ppb after an incubation step for 20 min.

Micellization and reversible pH-sensitive phase transfer of the hyperbranched multiarm PEI-PBLG copolymer

A novel, hyperbranched, amphiphilic multiarm biodegradable polyethylenimine-poly(gamma-benZyl-L-gluta- mate) (PEI-PBLG) copolymer was prepared by the ring-opening polymerization of gamma-benzyl-L-glutamate-N-car-boxyanhydride (BLG-NCA) with hyperbranched PEI as a macroinitiator. The copolymer could self-assemble into core-shell micelles in aqueous solution with highly hydrophobic micelle cores. As the PBLG content was increased, the size of the micelles increased and the critical micelle concentration (CMC) decreased. The surface of the micelles had a positive potential. The cationic micelles were capable of complexing with plasmid DNA (pDNA), which could be released subsequently by treatment with polyanions. The PEI-PBLG copolymer formed unimolecular micelles in chloroform solution. ne pH-sensitive phase-transfer behavior exhibited two critical pH points for triggering the encapsulation and release of guest molecules. Both the encapsulation and release processes were rapid and reversible. Under strong acidic or alkaline conditions, the release process became partially or completely irreversible.

Microstructures and properties of melt-spun and as-cast Mg-20Gd binary alloy

Mg-20Gd(%, mass fraction) samples were prepared using melt-spinning and copper mold casting techniques. Microstructures and properties of the Mg-20Gd were investigated. Results show that the melt-spun ribbon is mainly composed of supersaturated alpha-Mg solid solution phase and the as-east ingot mainly contains alpha-Mg solid solution and Mg5Gd phase. The differential scanning calorimeter (DSC) curve of the ribbon exhibits a small exothermic peak in the temperature range from 630 to 680 K, which indicates that the ribbon contains a metastable phase (amorphous). Tensile strength at room temperature of the melt-spun ribbon and as-cast specimen are 308 and 254 MPa, respectively. The elongations of the two samples are less than 2%. The fracture surfaces demonstrate that the fracture mode of the as-cast Mg-20Gd is a typical cleavage fracture and that of the melt-spun sample is a combination of brittle fracture and ductile fracture.

Comparison of biochemical effects induced by Changle between male and female rats using NMR and ICP-MS techniques

Metabolic profiles caused by rare earth complex were investigated using NMR and ICP-MS techniques. Male and female Wistar rats were treated orally with Changle (A kind of rare earth complex applied in agriculture to raise the production of crops) at dose of 2, 5 and 20 mg (.) kg(-1) body weight/day respectively for 90 d. Urine and serum samples are collected on 90 d. The relative concentrations of important endogenous metabolites in urine and serum are determined from H-1 NMR spectra and the contents of the four rare earth elements ( La, Ce, Pr and Nd) constituting Changle in the serum samples are measured by ICP-MS technique. Changle-induced renal and liver damage in rats is found based on the increase in the amounts of the amino acids, trimethylamine N-oxide, N, N-dimethyglycine, dimethylamine, succinate, aketoglutarate and ethanol as well as rare earth concentrations. The similarities and differentiations are found in the alteration patterns of metabolites and rare earth concentrations in serum.

Investigation on acute biochemical effects of Ce(NO3)(3) on liver and kidney tissues by MAS H-1 NMR spectroscopic-based metabonontic approach

High resolution magic angle spinning (MAS)-H-1 nuclear magnetic resonance (NMR) spectroscopic-based metabonomic approach was applied to the investigation on the acute biochemical effects of Ce(No-3)(3). Male Wistar rats were administrated with various doses of Ce (NO3)(3)(2, 10, and 50 mg(.)kg(-1) body weight), and MAS H-1 NMR spectra of intact liver and kidney tissues were analyzed using principal component analysis to extract toxicity information. The biochemical effects of Ce (NO3)(3) were characterized by the increase of triglycerides and lactate and the decrease of glycogen in rat liver tissue, together with an elevation of the triglyceride level and a depletion of glycerophosphocholine and betaine in kidney tissues. The target lesions of Ce (NO3)(3) on liver and kidney were found by MAS NMR-based metabonomic method. This study demonstrates that the combination of MAS H-1 NMR and pattern recognition analysis can be an effective method for studies of biochemical effects of rare earths.

Coating nano-hemalite on (Y,Gd)BO3 : Eu3+ phosphors by a facile method

(Y, Gd) BO3:Eu3+ particles coated with nano-hematite were prepared by a facile method I for example (humid) solid phase reaction at room temperature. The resulted hematite-coated (Y, Gd)BO3:Eu3+ particles were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) analysis, X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and photoluminescence spectra (PL). The SEM and EDS analyses indicate that the particles are coated with a very thin layer of iron oxide. XPS results further confirmed that the coating was hematite, and the coating thickness was in nanometer range. XRD patterns showed that either the hematite coating was too thin or the content of hematite was too small, so that the XRD cannot detect it. The emission spectra illustrate that the peak near 580 nm disappears due to the coating of iron oxide, and when the coating is very thin, the ratio of D-5(0)-> F-7(2) to D-5(2)-> F-7(1) of coated particles is higher than that of uncoated ones, which indicates that the color purity of the phosphor is increased by coating nano-hematite.

Extraction and stripping of ytterbium (III) from H2SO4 medium by Cyanex 923

The extraction and stripping of ytterbium (III) from sulfuric acid medium using Cyanex 923 in heptane solution was investigated. The effects of extractant concentration, pH and sulfate ion as well as stripping agents, acidity and temperature on the extraction and stripping were studied. The equilibrium constants and thermodynamic parameters, such as Delta H (10.76 kJ(.)mol(-1)), Delta G (-79.26 kJ(.)mol(-1)) and Delta S (292.41 J(.)K(-1.)mol(-1)), were calculated. The extraction mechanism and the complex species extracted were determined by slope analysis and FrIR spectra. Furthermore, it was found that the extraction of Yb (III) from sulfuric acid medium by Cyanex 923 increased with pH, concentration of SO42-, HSO4-, and extractant concentration, and approximately a quantitative extraction of Yb (III) was achieved at an equilibrium pH near 3.0, and the extracted complex was YbSO4(HSO4)(.)2Cyanex923((o)).

Effect of samarium on Mn activated zinc borosilicate storage glasses

Samarium and manganese co-doped zinc borosilicate storage glasses were prepared by high temperature solid state method. The effect of doping samarium on the defect of Mn activated sample was studied by means of thermoluminescence spectra. It was found that the shallower traps of the sample predominate with the addition of samarium, as a result, the phosphorescence and storage properties of the manganese doped zinc borosilicate glasses were greatly changed.