共查询到20条相似文献,搜索用时 15 毫秒
1.
D. I. Shlimas A. L. Kozlovskiy M. V. Zdorovets A. A. Mashentseva K. K. Kadyrzhanov 《High Energy Chemistry》2017,51(1):11-16
Results of targeted modification of the structure and properties of ordered arrays of zinc nanotubes (Zn NTs) by accelerated Xe+22 heavy ions with a fluence of 1 × 109 to 5 × 1011 cm–2 in the energy range of 1.0–1.75 MeV/nucleon are reported. Dynamics of changes in the crystallite shape and orientation of Zn NTs before and after irradiation has been studied by X-ray diffraction. It has been shown that irradiation with accelerated ions has a significant effect on the texture coefficients of Zn NTs. In addition, at a fluence of 1 × 1011 m–2 or higher, the formation of loose areas in the structure of Zn NTs as a result of partial degradation of the crystal structure and, consequently, a decline in conductivity are observed. 相似文献
2.
The absorption of Fe3+ ions from Fe3+-Zn2+ mixture with zinc and calcium phosphates was studied. 相似文献
3.
I. K. Battisha Y. Badr N. M. Shash M. G. El-Shaarawy A. G. A. Darwish 《Journal of Sol-Gel Science and Technology》2010,53(3):543-550
Nano-structure pure barium titanate BaTiO3 (BT) and (BT) co-doped with constant concentration of Er3+ ions and different concentrations of Yb3+ ions were prepared using sol–gel method. XRD results confirmed that the pure sample was found to crystallize in tetragonal
phase by sintering at 750 °C for 1 h. All major peaks corresponding to perovskite BT phase appeared. Efficient infrared-to-visible
up-conversion is reported in the doped samples. The conversion process and results in the generation of visible emissions
are discussed. Up-conversion efficiency for red emission predominates in doped samples. Results illustrate the large potential
of this class of materials for photonic applications in optoelectronics devices. 相似文献
4.
Ion-exchange modification of MF-4SK perfluorosulfonic membranes with Eu3+ and Tb3+ cations was realized. The state of cations in the membrane was studied by X-ray photoelectron spectroscopy. Special features of the luminescence of the resulting systems point to preferential excitation energy transfer from europium to terbium. 相似文献
5.
Abhijit P. Jadhav Sovann Khan Sun Jin Kim Seung Yong Lee Jong-Ku Park So-Hye Cho 《Research on Chemical Intermediates》2017,43(6):3463-3471
Properties of the quantum-cutting phosphors are dependent on various factors such as dopant concentration, crystallinity, homogeneity, particle size and surface morphology. Effective control of the above parameters can enhance the quantum-cutting ability of the phosphor material. Nano-sized particles of Y2O3:Tb3+,Yb3+ were prepared with a solution-based co-precipitation method and subsequent calcination. Effective control of the reaction parameters and doping concentration helped to produce uniform nanostructures with high quantum-cutting efficiency up to 181.1 %. The energy transfer mechanism between Tb3+ and Yb3+ was studied by considering their spectroscopic properties and time-resolved spectroscopy. The high efficiency and small particle size of the quantum-cutting phosphor Y2O3:Tb3+,Yb3+ make it a suitable candidate for its application in solar cells. 相似文献
6.
Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters
(ΔG
o, ΔH, ΔS) for the formation of the citrate complexes with the Mn2+, Co2+, Ni2+ and Zn2+ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic
strength of 100 mM was maintained with NaClO4. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes
have been discussed. 相似文献
7.
O. V. Davydova N. E. Drobyshevskaya E. N. Poddenezhnyi A. A. Boiko A. V. Zdravkov N. N. Khimich 《Russian Journal of Applied Chemistry》2016,89(10):1601-1606
Powders were synthesized in the yttrium oxide + zinc oxide system doped with europium oxide by the method of redox combustion of a mixture of yttrium, zinc, and europium nitrates in the presence of saccharose (fuel). The structure and the physicochemical and luminescent properties of the particles being formed and of a ceramic on their basis were examined. 相似文献
8.
D. E. Chirkst O. L. Lobacheva I. V. Berlinskii M. A. Sulimova 《Russian Journal of Applied Chemistry》2009,82(8):1370-1374
Experimental dependences of the distribution coefficients of cerium(III) and yttrium(III) dodecyl sulfates on the pH value
of the equilibrium aqueous phase in the course of ion flotation are reported. Conditions for separation of cerium(III) and
yttrium(III) are discussed. A value of the dissociation constant found from experimental results of potentiometric titration
of dodecylsulfuric acid with sodium hydroxide is presented. 相似文献
9.
A. I. Lytkin V. V. Chernikov O. N. Krutova I. A. Skvortsov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(6):1021-1025
Enthalpies of complex formation for glycine (HL±) with Ce3+ and Er3+ ions at 298.15 K and the value of the ionic strength of 0.5 (KNO3) are determined by calorimetric means using two independent procedures. Thermodynamic characteristics of the reactions of formation for complexes of glycine with Ce3+ and Er3+ ions at various [metal]: [ligand] molar ratios are calculated. 相似文献
10.
N. V. Nastapova A. S. Stepanov V. V. Yanilkin V. A. Burilov V. V. Skripacheva A. R. Mustafina S. E. Solov’eva A. I. Konovalov 《Russian Journal of Electrochemistry》2009,45(7):783-794
The electrochemical properties of n-sulfonatothiacalyx[4]arene (H4XNa4) complexes with [Co(dipy)3]3+ and Fe3+ ions were studied by means of cyclic voltammetry in aqueous solution at pH 2.5. The observed single-electron reduction of [Co(dipy)3]3+ bound extraspherically to the upper rim and Fe3+ ion bound intraspherically to the lower rim of n-sulfonatothiacalyx[4]arene in binary [Co(dipy)3]3+ · H3X5?, H3X5? · Fe3+, and ternary [Co(dipy)3]3+ · H3X5? · Fe3+ heterometal complexes was more difficult than in the free state. The reversible single-electron transfer to the metal ion results in lower binding energy ([Co(dipy)3]3+, ΔΔG 0 = 3.9 kJ/mol) or in full fast dissociation of the complex (Fe3+). The ternary complex in the solution forms the aggregates, in which inner encapsulated Fe(III) and Co(III) ions are not reduced on the electrode. Their quantitative reduction takes place by the relay mechanism of intra- and intermolecular electron transfer through electrochemically generated [Co(dipy)3]2+ outer ions. 相似文献
11.
S. N. Podyachev S. N. Sudakova V. V. Syakaev N. E. Burmakina R. R. Shagidullin V. I. Morozov L. V. Avvakumova A. I. Konovalov 《Russian Chemical Bulletin》2009,58(1):80-88
Synthesis of water-soluble potassium salts of carboxymethyl derivatives of calix[4]pyrogallols and dodeca(carboxylatomethyl)tetramethylcalix[4]pyrogallol
(L) complexes with transition metal ions (Cu2+, Fe3+, La3+) is described. Their structures in the solid state and in solution were characterized by NMR spectroscopy, ESR, and IR spectroscopy.
Calix[4]pyrogallol dodecacarboxylates exist in the rccc-configuration. Calix[4]pyrogallol with methyl substituents at the lower rim in a wide range concentrations exists in water
predominantly in the dimeric form. The obtained polynuclear transition metal complexes possess less symmetric structure than
potassium salt of calix[4]pyrogallol (K12L). All studied complexes contain water molecules bound by rather strong hydrogen bonds. At room temperature the Fe4L complex is characterized by the environment of the Fe3+ ions close to octahedral. The absence of signals in the ESR spectrum of the Cu6L complex indicates the strong antiferromagnetic interaction Cu2+-Cu2+. 相似文献
12.
Nizam M. El-Ashgar Issa M. El-Nahhal Mohamed M. Chehimi Michel Delamar Florence Babonneau Jacques Livage 《Journal of Sol-Gel Science and Technology》2007,41(1):3-10
A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH2)3-N[CH2CONH(C6H4)NH2]2, where P represents [Si–O]
n
polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH2)3N(CH2CO2Et)2 with 1,2-diaminobenzene in toluene. 13C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O).
The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1
metal to ligand complexes. 相似文献
13.
The software in MATHLAB medium has been developed to model ESR spectra of paramagnetic centers in single crystals. By means of this program, the angular dependences of ESR spectra found in KY(WO4)2, potassium yttrium tungstate, doped with gadolinium were analyzed. The spectra analysis indicates that they are determined by the presence of Gd3+ ions with the electron spin S = 7/2 occupying the structural position of Y3+ ions in the crystal structure. Parameters of spin Hamiltonian were defined for the analyzed ESR spectrum of Gd3+. Unusual features of the analyzed ESR spectra have been discovered in the region of 9.5 GHz which remind by appearance SHF line. The researches made show the position of this line to correspond to the region of quasi-intersection of energetic levels, and along with the line shape it is most likely to reflect the peculiarities of the region in whose interval wave functions of the energetic levels undergo substantial modifications. 相似文献
14.
15.
D. Mikolášová K. Rubešová V. Jakeš P. Nekvindová Z. Zlámalová Cílová J. Oswald 《Journal of Sol-Gel Science and Technology》2018,86(2):274-284
Compared to other oxide materials, the sol-gel deposition of an optically transparent LiNbO3 waveguiding film of sufficient thickness (approx. 1?μm) is complicated by the presence of a highly hydrolyzing Nb(V) in the starting solution. Thicker films require more concentrated solutions that are not easily achieved for such ions. This problem may be solved using strong chelating agents such as water-soluble polymers. To prepare a stable Er(III)/Yb(III)/Li(I)/Nb(V)/2-methoxyethanol solution with high metal concentration, we tested three such polymers: polyethylene glycol (PEG), polyacrylic acid (PAA) and polyvinyl alcohol (PVA), and compared them with already used polyvinylpyrrolidone (PVP). The solutions were spin-coated on crystalline sapphire substrates under a multi-step heating-deposition regime. Apart from Er3+/Yb3+ photoluminescence properties, we evaluated the influence of the film microstructure (SEM, AFM) on optical transparency and waveguiding ability in the UV/Vis/NIR region (transmission and m-line spectroscopy). Among the newly tested polymers, only PEG was able to prevent Nb(V) hydrolysis up to a maximum metal concentration of 0.6?mol/L. For PEG and PVP, the crystallization temperature of the deposited films (between 700?°C and 1000?°C) was compared. After further optimization of the heating-deposition process, we were able to prepare a transparent Er3+/Yb3+:LiNbO3 film thick enough to guide an optical signal in the NIR region. Thus, the use of PEG results is one of the very few non-hydrolytic sol-gel methods suitable for the preparation of not only luminescent, but also waveguiding Er3+/Yb3+:LiNbO3 structures. 相似文献
16.
S. B. Meshkova P. G. Doga A. A. Kucher 《Russian Journal of Coordination Chemistry》2017,43(10):657-662
The influence of the aggregate state on the IR luminescence is studied for the Nd(III), Sm(III), and Yb(III) complexes with the thienyl, phenyl, and alkyl derivatives of acetylacetone in solutions and as sorbates on the polymer matrix. It is found that the luminescence intensity of the sorbates of the complexes is 2–3 orders of magnitude higher than that in solutions due to the elimination of diffusion and respective intermolecular nonradiative losses of the excitation energy. 相似文献
17.
Two novel coordination polymers, namely {[Co(Ttac)0.5(1,4-Bib)(H2O)] · H2O}n (I) and {[La(HTtac)2(2H2O)] · H2O}n (II) (H4Ttac = 4,5-di(3'-carboxylphenyl)-phthalic acid, 1,4-Bib = 1,4-bis(1-imidazoly) benzene), have been designed and successfully prepared via hydrothermal process, and characterized by elemental analyses, IR spectroscopy, and single crystal X-ray diffraction (CIF files CCDC nos. 1039298 (I), 1039300 (II)). Structural analysis reveals that the H4Ttac ligands adopt different coordination modes in the as-synthesized I and II, and thus give rise to the targeted coordination polymers with different configurations. It is worth mentioning that, coordination polymer I is assembled from low-dimensional structures into three-dimensional (3D) via π···π stacking interactions, while three-dimensional coordination polymer II is formed by covalent bonds. Luminescent properties of coordination polymer II have been studied at ambient temperature. Significantly, luminescent measurement indicates that coordination polymer II may be acted as potential luminescent recognition sensors towards Cu2+ and Mn2+ ions. 相似文献
18.
M. Clara Gonçalves Luis M. Fortes Rui M. Almeida Alessandro Chiasera Andrea Chiappini Maurizio Ferrari Shivakiran Bhaktha 《Journal of Sol-Gel Science and Technology》2010,55(1):52-58
Er3+ photoluminescence (PL) and Yb3+ → Er3+ energy transfer (ET) phenomena in the near infrared (NIR) have been studied in three-dimensional (3-D) inverse opal (IO)
structures synthesized by a colloidal/sol–gel route, starting with the deposition of polystyrene microsphere (235 nm and 460 nm
diameter) direct opal templates by convective self-assembly, followed by infiltration of the interstices with Er3+/Yb3+-doped silica, titania and silica-titania sols and heat-removal of the polymeric template material. The crystalline quality
of the IOs has been optimized through suitable substrate treatments, plus the control of temperature and humidity during deposition
of the templates. The structural and optical properties of the 3-D opal and IO structures have been studied by field emission
scanning electron microscopy and visible-NIR reflection spectroscopy, in order to assess the relationship between microstructure
and the photonic properties obtained. Photonic bandgaps have been evidenced by the corresponding stop bands in the reflection
spectra. The shape and the intensity of the Er3+
4I13/2 → 4I15/2 transition at ~1.5 μm were modified in most IOs relatively to similar matrix deposits without a photonic crystal structure,
particularly in the case of pure silica and titania IOs, where the PL peak narrowed and intensified. It was not possible at
this stage to detect Yb3+ → Er3+ ET phenomena in the IOs structures. 相似文献
19.
Ethyl-substituted bis-triazinylpyridine (Et-BTP), a nitrogen containing soft-donor extractant, was used in investigations
pertaining to the separation of Am3+ and Eu3+ from dilute nitric acid feed solutions by extraction chromatography using XAD-4 as the inert support, chlorinated dicarbollide
as the modifier and 2-nitrophenyloctylether (NPOE) as the diluent. After carrying out a series of experiments, the optimum
composition of the extractant mixture for the resin was found out to be 0.1 M Et-BTP and 0.025 M CCD in NPOE. Separation factor
values were encouraging to carry out subsequent batch uptake studies at varying nitrate ion concentration which indicated
favourable separation behaviour up to NaNO3 concentration of 2 M. Column studies have been carried out and conditions for elution and separation of Am3+ from Eu3+ have been found out. Long term stability of the resin was also investigated. 相似文献
20.
The efficiency of calcium and magnesium phosphates of different compositions in the extraction of Cu2+, Zn2, and Co2+ ions from aqueous solutions was studied. 相似文献