Extraction of rare earths(III) from nitrate medium with di-(2-ethylhexyl) 2-ethylhexyl phosphonate and synergistic extraction combined with 1-phenyl-3-methyl-4-benzoy l-pyrazolone-5

The extraction of trivalent rare earths ( RE) from nitrate solutions with di-(2-ethylhexyl) 2-ethylhexyl phosphonate (DEHEHP, B) and synergistic extraction combined with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP, HA) were investigated. The extraction distribution ratios demonstrate a distinct "tetra effect," and Y lies between Tb and Dy when DEHEHP is used as a single extractant for RE. According to the corresponding separation factors (SF12) for adjacent pairs of rare earths, it could be concluded that DEHEHP could be employed for the separation of La from the other rare earths, and Y from light rare earths. The present work has also found that mixtures of HPMBP and DEHEHP have an evident synergistic effect for RE(III). Taking Y( III) as an example, a possible synergistic extraction mechanism is proposed. The enhancement of extraction in the binary system can be explained due to the species Y(NO3) (.) A(2) (.) HA (.) B formed. The synergistic enhancement coefficients ( R), extraction constants, formation constants and thermodynamic functions of the reaction were calculated.

Studies on the roles of different components in Cyanex 302 for rare earth ions extraction and separation

In this paper, the extractabilities of Cyanex 302 and purified Cyanex 302 (hereafter HBTMPTP or HA) in heptane have been compared by extracting the scandium, yttrium, lanthanum, and gadolinium from hydrochloric acid solutions. The roles of the different components in Cyanex 302 on lanthanum extraction have been analyzed. The result demonstrates that the Cyanex 302 has a higher extractability than HBTMPTP, which perhaps originates from the interaction among the components in Cyanex 302. Especially for R3PO, obviously synergistic effect can be observed in the lower pH range and extraction mechanism of lanthanum using the mixture of HBTMPTP and TOPO has been deduced to be:where (HA)(2) and B denote the dimeric form of HBTMPTP and TOPO, respectively. At the same time, the separation abilities of Cyanex 302 and HBTMPTP on the rare earth elements have been compared. Also, the effect of temperature on the extraction with Cyaenx 302, HBTMPTP and the mixture of HBTMPTP and TOPO has also been discussed with thermodynamic functions Delta H, Delta S, and Delta G calculated.

Luminescent properties of rare-earth-doped CaWO4 phosphor films prepared by the Pechini sol-gel process

CaWO4 phosphor films doped with rare-earth ions (Eu3+, Dy-,(3+) Sm3+, Er3+) were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, atomic force microscopy, and photoluminescence spectra, as well as lifetimes, were used to characterize the resulting powders and films. The results of the XRD analysis indicated that the films began to crystallize at 400degreesC and that the crystallinity increased with elevation of the annealing temperature. The doped rare-earth ions showed their characteristic emissions in crystalline CaWO4 phosphor films due to energy transfer from WO42- groups to them. Both the lifetimes and PL intensities of the doped rare-earth ions increased with increasing annealing temperature, from 500 to 900degreesC, and the optimum concentrations for Eu3+, Dy3+, Sm3+, Er3+ were determined as 30, 1.5, 1.5, 0.5 at.% of Ca2+ in CaWO4 films annealed at 900degreesC, respectively.

Mechanism of phase transformation and formation of barium hexaferrite doped with rare-earths in sol-gel process

The phase-transformation in sol-gel preparation of barium hexaferrite and the formation of barium hexaferrite doped with La3+ Were studied by chemical phase analysis, X-ray diffraction and infrared spectrometry analysis. The experimental results show that phase transformation reactions of FeCO3, Fe2O3 and BaFe2O4, barium hexaferrite and gamma-Fe2O3 take place in the heat treatment of gel. While the doping lanthanide ion replace barium ion, an equivalent quantity of Fe3+ are reduced to Fe2+ to maintain the charge equilibrium.

LB films of 2-n-heptadecanoylbenzoic-rare earth and their luminescence properties

Several ultrathin luminescent Langmuir-Blodgett (LB) films have been prepared by using the subphase containing the rare earth ions (Eu3+, Tb3-). The effect of the rare earth ions on the monolayer of 2-n-heptadecanoylbenzoic acid (HBA) was investigated. IR and UV spectra showed the rare earth ions were bound to the carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction. UV absorbance intensity increases linearly with the number of LB films layers, which indicate that the LB films are homogeneously deposited. The LB films can give off strong fluorescence. and the signal can be detected from a single layer. The characteristic luminescence behaviors of LB films have been discussed compared with those of the complexes.

Luminescence properties of LB films based on heteropolytungstate of rare earth

In this work, the LB films based on heteropolytungstate of Dy and Sm have been prepared. The X-ray diffraction shows the LB films have a highly ordered lamella structure. The luminescence characteristics of the LB films were studied. The charge transfer bands of LB films are in higher energies than those of the corresponding solids. It is noticed that the yellow to blue intensity ratio (Y:B) of Dy3+ in the LB films is different from that of the solid. The differences in the spectra show that the Dy3+ site symmetry in LB film was changed due to the interaction between the surfactant and the polyanions. The differences could also be found in the luminescence spectra of the LB films of Sm complex.

Luminescent self-assembled thin films based on rare earth-heteropolytungstate

earth (Eu3+, Dy3+)-heteropolytungstate thin films were fabricated by self-assembly method successfully. The thin films give off strong fluorescence, which can be observed by eyes upon UV irradiation. The characteristic emission behaviors of the rare earth ions in self-assembled thin film were investigated compared with those of the corresponding solids. It is noticed that the intensity ratio between D-5(0) --> F-7(2) and D-5(0) --> F-7(1) of Eu3+ and the intensity ratio between F-4(9/2) --> H-6(13/2) and F-4(9/2) --> H-6(15/2) of Dy3+ in the self-assembled films are different from those of the corresponding solids. Furthermore, the self-assembled films present shorter fluorescence lifetimes than the corresponding solids. The reasons for these results have been discussed.

Multi-color long-lasting phosphorescence of rare earth ions in CdSiO3 matrix

A series of rare earth ions doped CdSiO3:RE3+(RE=Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) multi-color long-lasting phosphorescence phosphors are prepared by the conventional high-temperature solid-state method. The results of XRD measurement indicate that the products fired under 1050degreesC for 3 h have a good crystallization without any detectable amount of impurity phase. Rare earth ions doped CdSiO3 phosphors possess excellent luminescence properties. When rare earth ions such as Y3+, La3+, Gd3+, Lu3+, Ce3+, Nd3+, Ho3+, Er3+, Tm3+ and Yb3+ are introduced into the CdSiO3 host, one broadband centered at about 420 nm resulting from traps can be observed. In the case of other earth ions such as Pr3+, Sm3+, Eu3+, Tb3+ and Dy3+, their characteristic line emitting as well as the similar to420 nm broadband luminescence can be obtained. The mixture of their characteristic line emitting with the similar to420 nm broadband luminescence results in various afterglow color.

Copolymerization of CO2 and propylene oxide under rare earth ternary catalyst: design of ligand in yttrium complex

Copolymerization of carbon dioxide and propylene oxide was carried out employing (RC6H4COO)(3)Y/glycerin/ZnEt2 (R = -H, -CH3, NO2, -OH) ternary catalyst systems. The feature of yttrium carboxylates (ligand, substituent and its position on the aromatic ring) is of great importance in the final copolymerization. Appropriate design of substituent and position of the ligand in benzoate-based yttrium complex can adjust the microstructure of aliphatic polycarbonate in a moderate degree, where the head-to-tail linkage in the copolymer is adjustable from 68.4 to 75.4%. The steric factor of the ligand in the yttrium complex is crucial for the molecular weight distribution of the copolymer, probably due to the fact that the substituent at 2 and 4-position would disturb the coordination or insertion of the monomer, lead the copolymer with broad molecular distribution. Based on the study of ultraviolet-visible spectra of the ternary catalyst in various solvents, it seems that the absorption band at 240-255 nm be closely related to the active species of the rare earth ternary catalysts.

Low temperature preparation of ceria solid solutions doubly doped with rare-earth and alkali-earth and their properties as solid oxide fuel cells

A series of solid electrolytes, (Ce(0.8)Ln(0.2))(1 - x)MxO2 - delta(Ln = La, Nd, Sm, Gd, M:Alkali-earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 degreesC. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte is improved. The effects of rare-earth and alkali-earth ions on the electricity were discussed. The open-circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce0.8Sm0.2)(1 - 0.05)Ca0.05O2 - delta as electrolyte are 0.86 V and 33 mW . cm(-2), respectively.

The optical spectroscopic properties of rare earth-activated barium orthophosphate in VUV-Vis range

The optical properties of rare earth ions-activated barium orthophosphate phosphors, Ba-3(PO4)(2):RE (RE = Ce3+, Sm3+, Eu3+, Eu2+, and Tb3+), were investigated in vacuum ultraviolet (VLTV)-Vis range. A band-band transition Of PO43- in Ba-3(PO4)(2) is observed in the region of 150-170 nm. The partial reduction of Eu3+ to Eu2+ was observed and confirmed by luminescent spectra under the VUV-UV excitation. It is proposed that the electronegative defects that formed by aliovalent substitution of Eu3+ on the Ba2+ site in the host are responsible for the reduction process.

VUV-UV excited luminescent properties of calcium borophosphate doped with rare earth ions

The VUV-UV spectra of rare earth ions activated calcium borophosphate, CaBPO5:RE (RE = Ce3+, sm(3+), Eu2+, Eu3+, Tb3+ and Dy3+) were determined. The bands at about 155 nm in the VUV excitation spectra are attributed to the host lattice absorptions. The bands at 166 and 190 nm for the sample CaBPO5:Sm have been considered as related to the f-d transition and the charge transfer band (CTB) of Sm3+ ions, and the band at 169 nm for the sample CaBPO5:Dy is assumed to be connected with the f-d transition of the Dy3+ ions in CaBPO5. The partial reduction of Eu3+ CaBPO5:Eu prepared by high temperature solid state reaction in air is confirmed by the VUV-UV spectra.

Extraction mechanism of rare earths with sec-octylphenoxy acetic acid by two-phase titration technique

The compositions of the extracted complexes of La, Gd, Er and Y with sec-octyl-phenoxy acetic acid in heptane and the related apparent extraction equilibrium constants K-M were determined using two-phase titration technique. The stoichiometric compounds for La, Gd, Er and Y should be LaA(3) . 2.5HA, GdA(3) . 3HA, ErA(3) . 3.1HA and YA(3) . 4.3HA respectively. And their pK(M) are 3.43, 3.46, 3.08 and 2.58 respectively.

Red light-emitting diodes based on rare earth complex Eu (TTA)(4)C5H5NC16H33

A thin film electroluminescence cell with the structure of ITO/PPV/PVK:Eu(TTA)(4)C5H5NC16H33:PBD/Alq(3)/Al has been fabricated. Red emission with a very sharp spectral band at 614nm was observed and a maximum luminance of 20cd . m(-2) at 36V was obtained from the spin-coated device. The full width at half maximum of luminescent spectrum is less than 10nm.

Preparation, photo and electroluminescence properties of novel rare earth aromatic carboxylates

Novel soluble rare earth aromatic carboxylates were prepared. The triplet energy level of organic ligand was measured. The photoluminescence properties of the Tb3+ and EU3+ aromatic carboxylates and lifetimes were investigated, which indicated that these rare earth complexes have high quantum efficiency. Because of their excellent solubility, polymer-doping rare earth carboxylates were fabricated as thin Films by spin-coating method and their luminescence properties were studied. Some rare earth organic light-emitting diodes were successfully fabricated which performed high pure color. The maximum luminance of the device of ITO/PVK/PVK :Th (AS)(3)Phen: PBD/PBD/Al is 32 cd(.)m(-2) at 28 V.