51 resultados para RE3
Resumo:
--- 1 HDEHP HHEOIPP Cyanex272 Cyanex302Cyanex301HEHEHPRE3+ 2 isooctanolHEHEHPYb3+ 3 HEHEHP-isooctanolisooctanolHEHEHP-Yb3+-HCl 4 [C8mim][PF6] ()HEHEHPHEHEHP- ILHEHEHP
Resumo:
PDP-PDPPDPPDP- PDPPDPPDPYGdBO_3LaGdPO4YGdVO4YPVO_4LoBSIOSXRDIRSEMXPSTG-DTAPDPVUV1Y,GdBO_3RE~(3+)REEuThVUVsEM100-200nmXPSY,GdBO_3RE~(3+)VUV110-175nmB3G"B-OGGY,GdBO3:RE3Gd3RE3PDPEu3Th3GdB03Y,GdBO3Eu~(3+)2GPDPL aGdPo4RE3REEuTb2HPO4pH5240oC3SEMLaP04Eu3+GdPO4Eu3+Gd3LaGdPO4KE3RE=EuTbVUVGd3Gd3Gd3LaGdPO4Eu3+Gd3Eu3+xPsLaPO4GdP04LaP04O22PGdPo4O2-2pGd34fLaGdPO4RE3VUV3Y,GdVO4Eu3+VUV120-170nmvO43200nm2PO4fY5d20onmEu3VO43-Gd3YGdVO4E"vLJ'vGGd3vo43+Eu3+Y,GdVO4Eu3+Y,Gdvo4EusVO_4~(3-)Eu~(3+)VO_4~(3-)vuvGd~(3+)VO_4~(3-)UVEu~(3+)Gd34YPvO4Eu3"pH12.52406YPVo4Eu3XRDSEMYPVO4Eu3VO3-4YPO4Eu3+100-150nmYVO4Eu3+400-450nmYP VO4:Eu3+VUVEu3+VO3-4~5D_0~7F_2~5D_0~7F_1VO_4~(3-_VO4YPVO4Eus"VUVYP,VO4Eu35LaBSIOSSEM2-3mLaBSiO_5Eu~(3+)1300-400cm~(-1)BO_4SiO_4LaBSiO_5:Re~(3+)RE=EuSmThvuvVUV125-200nmBO_4125-165nmSiO4165-183nmLaBSiO_5RE~(3+)REEuSmTb254nm
Resumo:
AAO5200nmAAOAAOAAOM2O3:RE3+MY,Gd; REEuTbAAOAAO15Onm35nm2OnmAAOAAO2XRD331AAOAAO-Al2O33AAO350600nm435nm4AAOYO.96RE0.05O3REEuTbSEMEDXTEMSAEDXRDPLx-XRDSAEDRE2O3REYGdEu3D07F2Tb35D47FJJ=65435M2O3:RE3MYGdREEuTbAAO6M2O3:RE3M=YGdREEuTbO7YGd2O3:Eu3+AAOAAO 8M2O3: RE3+MYGdREEuTb0AAO
Resumo:
beta-NaYF4:Ln(3+) (Ln = Eu, Tb, Yb/Er, and Yb/Tm) hexagonal microprisms with remarkably uniform morphology and size have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. It is found that sodium citrate as a shape modifier introduced into the reaction system plays a critical role in the shape evolution of the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting the molar ratio of citrate/RE3+ (RE represents the total amount of Y3+ and the doped rare earth elements such as Eu3+, Tb3+, Yb3+/Er3+, or Yb3+/Tm3+). Under the excitation of 397 nm ultraviolet light, NaYF4:xEu(3+) (x = 1.5, 5%) shows the emission lines of Eu3+ corresponding to D-5(0-3) -> F-7(J) (J = 0-4) transitions from 400 to 700 nm (whole visible spectral region) with different intensity, resulting in yellow and red down-conversion (DC) light emissions, respectively.
Resumo:
A series of solid state electrolytes, Ce-5.2 RE0.8 MoO15-delta (RE = Y, La, Sm, Gd, Dy, Ho, Er), were synthesized by sol-gel method. Their structures and electrical conductivities were characterized by X-ray Diffraction (XRD), Raman and X-ray Photoelectron Spectroscopy (XPS) and AC impedance spectroscopy, respectively. The results show that the concentrations of oxygen vacancy increased with increasing x and their conductivity were improved. And the cell parameters increase as the radius of RE3+ increases. Because the ionic radius of doped Dy3+ (0.0908 nm) is closed to that of Ce4+ (0.0920 nm), their oxide has minimal cell elastic straining between RE3+ and oxygen vacancy, and the system has the least association enthalpy, thus the oxide Ce-5.2 Dy-0.8 MoO15-delta exhibits a higher conductivity (7.02 x 10(-3) S/cm) and lower activation energy (1.056 eV) compared to the other doped compounds.
Resumo:
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.
Resumo:
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.
Resumo:
The reduction of Eu3+ to Eu2+ in air has been observed in a silicate matrix for the first time in BaMgSiO4:Eu prepared by high-temperature solid-state reaction. Emission and excitation spectra were employed to detect the presence of Eu2+ ions in the compound and this reduction was explained by a charge compensation model proposed previously. In BaMgSiO4 : Eu2+, Eu2+ ions occupy three different lattice sites by substitution for Ba2+ ions. Eu2+ ions on Ba(1) and Ba(2) sites gave emissions at about 500 nm while that on Ba(3) site showed an emission band at 398 nm. All the emissions of Eu2+ ions in BaMgSiO4 : Eu2+ were not quenched at room temperature.
Resumo:
Sr4Al14O25RE3+(RE=Eu,Ce,Tb),Eu3+,Ce3+Tb3+,Ce3+Tb3+;Eu3+,Ce3+Tb3+,Eu2+;Tb3+5D35D4,;Ce3+Tb3+
Resumo:
( La,Gd) PO4 RE3 +( RE=Eu,Tb) .Gd PO4 La PO4 , . ( La,Gd) PO4 RE3 + ,Gd3 + .XPS ,La PO4 O2 - 2 p , Gd PO4 O2 - 2 p Gd3 + 4 f.
Resumo:
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.
Resumo:
The local structure and the valences of europium in SrBPO5:Eu prepared in air were checked by means of XAFS at Eu-L-3 edge. From the EXAFS results, it was discovered that the doped europium atoms were nine-coordinated by oxygen atoms and the distances of bond Eu-O were 2.42 Angstrom in the host. From the XANES data, it was found that the divalent and trivalent europium coexisted in the matrix. The emission spectra excited by VUV or UV exhibited a prominent broad band due to the 4f(6)5d-4f(7) transition of Eu2+ ions, which indicated that the trivalent europium ions were reduced in air in the matrix at high temperature by the defects [V-Sr]" formed by aliovalent substitution between Sr2+ and Eu3+ ions. The VUV excitation spectra in 100-200 nm range showed that the matrix had absorption bands with the maxima at about 130 and 150 nm, respectively.
Resumo:
Two kinds of rare earth (RE) complexes were intercalated into zirconium bis(monohydrogenphosphate) (alpha -ZrP) by exchanging the RE complexes into the p-methyoxyaniline (PMA) preintercalated compound Zr(O3POH)(2). 2PMA (alpha -ZrP . 2PMA). Powder X-ray diffraction patterns reveal that Eu(DBM)(3)phen (DBM: dibenzoylmethane, phen: 1,10-phenanthroline) and Tb(AA)(3)phen (AA: acetylacetone) intercalated into alpha -ZrP . 2PMA. This was confirmed by the UV-visible spectra of both the RE complexes and the assemblies. At the same time, the assemblies have better luminescent properties, and the fluorescent lifetimes of RE3+ in the excited state in the assemblies are much longer than those in the complexes. The stabilities of the assemblies under UV radiation are much better than those of the RE complexes.
Resumo:
, YAGYAGRE3+ (RE =Eu ,Dy) (1% , ) ,XRD ,TG DTA YAGYAGEu 80 0 90 0Eu3+ YAG , , ,90 0 10 0 0
Resumo:
The investigations of classification on the valence changes from RE3+ to RE2+ (RE = Eu, Sm, Yb, Tm) in host compounds of alkaline earth berate were performed using artificial neural networks (ANNs). For comparison, the common methods of pattern recognition, such as SIMCA, KNN, Fisher discriminant analysis and stepwise discriminant analysis were adopted. A learning set consisting of 24 host compounds and a test set consisting of 12 host compounds were characterized by eight crystal structure parameters. These parameters were reduced from 8 to 4 by leaps and bounds algorithm. The recognition rates from 87.5 to 95.8% and prediction capabilities from 75.0 to 91.7% were obtained. The results provided by ANN method were better than that achieved by the other four methods. (C) 1999 Elsevier Science B.V. All rights reserved.
