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61.
Ytterbium, erbium, aluminum tri-doped zinc oxide crystal was synthesized, which can turn color from red to green up-conversion luminescence through adjusting aluminum content. When the aluminum concentration reached 4?mol%, the color of up-conversion emission first turn from red to green. Meanwhile, the ratio of red to green emission reduced from 25.32 to 0.26, and the coordinates of chromaticity coordinate calculation changes from (0.5749, 0.3378) to (0.2190, 0.7169) with aluminum concentration range from 0 to 4?mol%. The up-conversion emission peaks at 521, 542, and 660?nm of sample originate from the transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of erbium ions, respectively. X-ray diffraction patterns perform the better crystallization degree with increasing aluminum concentration. The scanning electron microscopy images show the porous and lamellar structures with different aluminum concentrations. A convenient but effective design to obtain ytterbium, erbium, aluminum tri-doped zinc oxide up-conversion luminescence is reported, which can turn color from red to green. 相似文献
62.
《Journal of Coordination Chemistry》2012,65(9):1560-1578
abstractPoly[tris(dimethylformamide)(μ3-2,4,6-triiodol-1,3,5-benzene tricarboxylic acid)-praseodymium (III)] {Pr(TIBTC)(DMF)3}n (1) (H3TIBTC = 2,4,6-triiodo-1,3,5-benzene tricarboxylic acid) was synthesized by the reaction of Pr(NO3)3·6H2O and H3TIBTC at 85°C in a pyrex vial. 1 was characterized by elemental analysis, IR, UV–vis, TGA, PXRD, and atomic force microscopy analytical means. Each of the central Pr ions and the three carboxyl groups from the same ligand constitute a SBU, which is then joined by a carboxyl group to form a building block. In order to further explore the functional properties of 1, we used this compound for adsorption experiments. It is found that 1 can effectively adsorb anionic dyes in aqueous solutions. In particular, there is a good adsorption efficiency for coomassie brilliant blue R-250. Therefore, 1 shows good prospects for selective adsorption of anionic dyes from wastewater solution. 相似文献
63.
K. Wetzel 《Isotopes in environmental and health studies》2013,49(12):408-413
Die Isotopenzusammensetzung der chemischen Elemente in ihren natürlichen Vorkommen wird von kernphysikalischen Vorgängen, vom Einfall extraterrestrischer Materie und, namentlich bei den leichten Elementen (etwa bis zum Chlor), von kinetischen und thermodynamischen Isotopieeffekten beeinfluβt. Deshalb ist die Kenntnis der in der Natur wirkenden Isotopieeffekte eine entscheidende Voraussetzung für das Verständnis der Gesetzmäβigkeiten der Verbreitung der Isotope in der Natur und für die Anwendung dieser Gesetzmäβigkeiten als Mittel der geo- und kosmoswissenschaftlichen Forschung und der Umweltforschung [1]. 相似文献
64.
Abstract The photoacoustic(PA) amplitude and phase spectra of several kinds of rare earth (RE) complexes are reported and summarized briefly. It is observed that both the amplitude and phase spectra well characterize the different energy levels of the RE complexes. The phase angle of the RE complexes is associated with the relaxation time τ and the optical absorption coefficient β concerning with the π-π? transition and the f-f transitions, respectively. After individual detailed discussion of the phase spectra, a reasonable theoretical consideration is given to interpret the results. 相似文献
65.
Sophia J. Makowski Evelyn Calta Michael Hörmannsdorfer Prof. Dr. Wolfgang Schnick 《无机化学与普通化学杂志》2012,638(2):345-351
The stability against hydrolysis of triazine tricarboxylate (TTC) in the presence of divalent transition metal and alkaline earth ions was investigated by means of X‐ray diffraction and FTIR spectroscopy. Depending on the size of the cation either formation of the respective triazine tricarboxylate salts or hydrolysis of TTC yielding oxalate was observed. The hydrolysis of TTC induced by transition metal ions could be explained in analogy to the hydrolysis of triazine tris(2‐pyrimidyl) as a result of ring tension caused by the coordination of these ions. By the reaction of potassium triazine tricarboxylate with alkaline earth salts in aqueous solution the alkaline earth triazine tricarboxylates M3[C3N3(CO2)3]2 · 12H2O (M = Sr, Ba) were obtained and analyzed by single‐crystal X‐ray diffraction. The isotypic salts represent the first examples of alkaline earth triazine tricarboxylates and the first TTC salts comprising solely divalent cations. 相似文献
66.
Matthias Eul Manfred H. Möller Rolf‐Dieter Hoffmann Wolfgang Jeitschko Prof. Dr. Rainer Pöttgen 《无机化学与普通化学杂志》2012,638(2):331-335
The phosphide oxide La2AuP2O was synthesized from lanthanum filings, dried La2O3, gold pieces, and ground red phosphorus in the ideal 1.33:0.33:1:2 ratio in an evacuated silica tube at 1473 K. Small single crystals were obtained by recrystallization in a NaCl/KCl flux. The structure was determined on the basis of single‐crystal X‐ray diffractometer data: new type, C2/m, a = 1537.3(3), b = 427.39(8), c = 1009.2(2) pm, β = 131.02(1) °, wR2 = 0.046, 1102 F2 values, 38 variables. La2AuP2O contains two striking structural motifs: The oxygen atoms are located in La4 tetrahedra. The latter are cis‐edge‐shared forming polymeric cationic [La2O]4+ chains. These cationic units are separated and charge‐balanced by [AuP2]4– polyanions which have monovalent gold in distorted trigonal planar phosphorus coordination. Two crystallographically independent phosphorus sites occur in the polyanion, i.e. isolated P3– besides dumb‐bells P24– (P2–P2 223 pm). La2AuP2O, which crystallizes in the form of ruby red transparent crystals, is an electron precise phosphide oxide (4La3+)(2Au+)(2P3–)(P24–)(2O2–). 相似文献
67.
NaYF4:Eu/Sr nanocrystals were synthesized by a hydrothermal method. Tunable photoluminescence of the NaYF4:Eu nanocrystals was successfully achieved by codoping with Sr2+ ions. With increasing Sr2+ concentration, not only the X-ray diffraction peaks of the nanocrystals become broader, but also the positions of them shift toward larger lattice parameters. Eu3+ and Eu2+ have been found to coexist in an NaYF4:Eu/Sr. The Eu3+/Eu2+ emission intensity ratio changed with the Sr2+ concentration and excitation wavelength. More interestingly, the spectral configurations of Eu2+ and Eu3+ also varied with the excitation wavelength, indicating that the nanocrystals have multiple luminescence centers or emitting states. 相似文献
68.
Fluoride is an essential element, indispensable for maintenance of dental health. Nevertheless, fluoride concentrations in drinking water above 1.5 mg L−1 may be detrimental to human health. Many methods have been developed for removing excessive fluoride from drinking water, adsorption seems to be an effective, environmentally friendly and economical one. Since the sorption capacity of fluoride below 2 mg L−1 on most conventional adsorbents is not satisfactory, much effort has been devoted to develop new and cost-effective fluoride adsorbents. This review reports the recent developments in the F− removal in water treatment, using chitosan derivatives and composites in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan derivatives and composites under different experimental conditions is reported to help to compare the efficacy of the fluoride removal process. A comparison with the adsorption capacity of other low cost adsorbents is also tabled. 相似文献
69.
Gandham Lakshminarayana 《Journal of solid state chemistry》2011,184(8):1931-1938
We report on Tb3+ as efficient sensitizer for red photoemission from Mn2+-centers in ZnO-B2O3-Al2O3-Si2O-Na2O-SrO glasses and corresponding gahnite glass ceramics. In comparison to singly or co-doped glasses, the glass ceramics exhibit significantly increased emission intensity. Structural considerations, ESR, and dynamic luminescence spectroscopy indicate partial incorporation of Mn2+ as well as Tb3+ into the crystalline phase, the former on octahedral Zn2+-sites. Interionic distance and charge transfer probability between both species depend on crystallization conditions. This enables control of the energy transfer process and, hence, tunability of the color of photoemission by simultaneous emission from Tb3+ and Mn2+ centers. Concentration quenching in Mn2+-singly doped materials was found at a critical dopant concentration of about 1.0 mol%. The energy transfer process was studied in detail by dynamic as well as static luminescence spectroscopy. Spectroscopic results suggest the application of the studied materials as single or dual-mode emitting phosphor for luminescent lighting. 相似文献
70.