Structural and mass transport properties of liquid ytterbium in the temperature range 1123 K–1473 K

We have studied the structural and atomic transport properties of liquid f-shell Yb in the temperature range 1123 K–1473 K. Pair interactions between atoms are derived using a local pseudopotential. The potential parameters are fitted to the phonon dispersion curve at room temperature. The local pseudopotential used in the present study is computationally more efficient with only three parameters, and it is found to be transferable to the liquid phase without changing the parameters.Since the various computed properties agree with reported theoretical and experimental findings, the adopted fitting scheme is justified. As a significant outcome of the study, we find that(i) the melting in Yb is governed by the Lindemann's law,(ii)the mass transport mechanism obeys the Arrhenius law,(iii) the role of the three-particle correlation function in deriving the velocity autocorrelation function is small,(iv) the mean-square atomic displacement is more sensitive to the choice of interaction potential than the other bulk properties, and(v) liquid Yb does not show liquid–liquid phase transition within the studied temperature range. Further, due to the good description of the structural and mass transport properties, we propose that Yb remains divalent at reduced density.

Ridge regression energy levels calculation of neutral ytterbium(Z=70)

In view of the difficulty in calculating the atomic structure parameters of high-Z elements,the Hartree–Fock with relativistic corrections(HFR)theory in combination with the ridge regression(RR)algorithm rather than the Cowan code’s least squares fitting(LSF)method is proposed and applied.By analyzing the energy level structure parameters of the HFR theory and using the fitting experimental energy level extrapolation method,some excited state energy levels of the Yb I(Z=70)atom including the 4f open shell are calculated.The advantages of the ridge regression algorithm are demonstrated by comparing it with Cowan code’s LSF results.In addition,the results obtained by the new method are compared with the experimental results and other theoretical results to demonstrate the reliability and accuracy of our approach.

Numerical studies of isotopic selective photoionization of ytterbium in a three-step ionization scheme

Selective photoionization of ytterbium isotope is studied numerically based on a three-step photoionization scheme,4f^(14)6s^(21)S_0(0 cm^(-1))→4f~(14)6s6p~3P_1(17992.008 cm^(-1))→(4f~(13)6s~26p)(7/2,3/2)_2(35196.98 cm^(-1))→auto-ionization state(52353 cm^(-1))→Yb^(+),by the density matrix theory with the consideration of atomic hyperfine structures and magnetic sublevels.To examine the physical model,the numerical isotopic abundance of ytterbium is compared with that from mass spectroscopy experiment,showing that they are in good agreement with each other.The excitation process and ionization process of ytterbium,especially for odd isotopes,are discussed and analyzed in detail on this basis.The effects of frequency detuning,power densities,spectral bandwidths,polarization of two excitation lasers,and atomic Doppler broadening on the total ionization yield and isotopic abundance are investigated numerically and the optimal excitation conditions for~(176)Yb enrichment are identified semi-quantitatively.

Recovery of rare earth element ytterbium(Ⅲ) by dried powdered biomass of spirulina: Adsorption isotherm, kinetic and thermodynamic study

The adsorption characteristics and mechanisms of spirulina powder were investigated when it was used as adsorbent to recover ytterbium(Ⅲ) from wastewater solution. Surface structure and element valence of the adsorbent were analyzed by SEM and XPS for the exploring of its adsorption mechanism for ytterbium(Ⅲ). The adsorption characteristics of ytterbium(Ⅲ) on spirulina powder was analyzed through assessing adsorption isotherm, kinetics and thermodynamic models. The adsorption isotherm data were best explained by Langmuir model, and the adsorption capacity of spirulina powder for ytterbium(Ⅲ) was 72.46 mg/g when adsorption temperature was 318 K. The kinetic experiment results showed that the pseudo-second order kinetic model can better simulate the adsorption process of spirulina powder to ytterbium(Ⅲ), indicating that the rate-controlling step was chemical adsorption. Spirulina can be an efficient and economical ytterbium(Ⅲ) recycling material, because it showed good adsorption stability and reusability from the adsorption-desorption cycle experiment results.

Frequency stabilization of a 399-nm laser by modulation transfer spectroscopy in an ytterbium hollow cathode lamp

The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.

Extraction and Stripping of Ytterbium (Ⅲ) from H_2SO_4 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 extraetant 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 △n （10.76 kJ·mol^-1）, △G （-79.26 kJ·mol^-1） and △S （292.41 J·K^-1·mol^-1）, were calculated. The extraction mechanism and the complex species extracted were determined by slope analysis and FTIR spectra. Furthermore, it was found that the extraction of Yb （Ⅲ） from sulfuric acid medium by Cyanex 923 increased with pH, concentration of SO4^2-, 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）.

Extraction and Separation of Thorium and Ytterbium with Bis(2,4,4-Trimethylpentyl) Phosphinic Acid Using a Hollow Fiber Membrane Extractor

The based membrane extraction of Th 4+ and Yb 3+ was studied in HBTMPP heptane using a hollow fibber membrane. The separation method of Th 4+ and Yb 3+ was proposed by kinetics competition. The separation operation of Th 4+ and Yb 3+ mixture was carried out by two successive extraction and stripping simultaneously. The concentration ratio of Th 4+ to Yb 3+ is 16 74 in the stripping solution. The recovery and purity of Th 4+ are 71 6% and 95 74% respectively.

H_2S Gas Sensitivity of Nanocrystalline Tin Dioxide Doped with Ytterbium (Yb) and Praseodymium (Pr)

<正>The influence of Yb_2O_3 and Pr_2O_3 doping on electrical and gas sensing properties of tin dioxide was studied.A doping content of 0.5wt%～5wt% was investigated by mechanical mixing.The significant improvement on sensitivity and selectivity to 200μg/g hydrogen sulphide gas has been achieved by 3wt% Pr_2O_3 and 5wt% Yb_2O_3 adding.The better response and revovery properties of Pr or Yb doped tin dioxide sensor for 200μg/g hydrogen sulphide gas were found.The maximum sensitivity to H_2S gas is observed at about 120℃.Pr has stronger catalysis than Yb for H_2S reaction on SnO_2 surface.S~ 2-) was oxidized to S~ 6+) on the SnO_2 surface according to XPS.

Determination of micro yttrium in an ytterbium matrix by inductively coupled plasma atomic emission spectrometry and wavelet transform

In the determination of trace yttrium (Y) in an ytterbium (Yb) matrix byinductively coupled plasma atomic emission spectrometry (ICP-AES), the most prominent line ofyttrium, Y 371.030 nm line, suffers from strong interference due to an emission line of ytterbium.In mis work, a method based on wavelet transform was proposed for the spectral interferencecorrection. Haar wavelet was selected as the mother wavelet. The discrete detail after the thirddecomposition, D3, was chosen for quantitative analysis based on the consideration of bothseparation degree and peak height. The linear correlation coefficient between the height of the leftpositive peak in D3 and the concentration of Y was calculated to be 0.9926. Six synthetic sampleswere analyzed, and the recovery for yttrium varied from 96.3 percent to 110.0 percent. The amountsof yttrium in three ytterbium metal samples were determined by the proposed approach with an averagerelative standard deviation (RSD) of 2.5 percent, and the detection limit for yttrium was 0.016percent. This novel correction technique is fast and convenient, since neither complicated modelassumption nor time-consuming iteration is required. Furthermore, it is not affected by thewavelength drift inherent in monochromators that will severely reduce the accuracy of resultsobtained by some chemometric methods.

Theoretical study on isotope separation of an ytterbium atomic beam by laser deflection

Isotope separation by laser deflecting an atomic beam is analyzed theoretically. Interacting with a tilted one- dimensional optical molasses, an ytterbium atomic beam is split into multi-beams with different isotopes like 172yb, Jv3yb, and J74yb. By using the numerical calculation, the dependences of the splitting angle on the molasses laser intensity and detuning are studied, and the optimal parameters for the isotope separation are also investigated. Furthermore, the isotope separation efficiency and purity are estimated. Finally a new scheme for the efficient isotope separation is proposed. These findings will give a guideline for simply obtaining pure isotopes of various elements.

SEPARATION OF THORIUM FROM YTTERBIUM WITH CYANEX272 BY USING A HOLLOW FIBER MEMBRANE EXTRACTOR

The based membrane extraction of Th(IV) and Yb(III) was studied with HBTMPP in heptane. The separation process of Th(IV) and Yb(III) was considered to be a kinetics competition one. The separation for the mixture of Th(IV) and Yb(III) was carried out by successive membrane extraction and stripping simultaneously. The concentration ratio of Th(IV) and Yb(III) is 16.74 in the stripping solution. The recovery of Th(IV) is 71.6%. The purity of Th(IV) is 95.74%. The separation factor of Th(IV) and Yb(III) is 2.52×106, which was obtained by interfacial kinetics.

Synthesis and Crystal Structure of Tetra(diisopropyl-amido-N)ytterbium Mono(tetrahydrofuran-O)lithium

The reaction of anhydrous YbCl3 with LiNPri2 in 1:3 molar ratio gave the homo- leptic lanthanide amide ate complex Yb(C6H14N)4Li(C4H8O). The crystal structure was determined by X-ray diffraction and the following crystallographic data were obtained: C28H64N4OYbLi, Mg = 652.82, monoclinic, P21/c (#14), a = 15.239(3), b = 21.502(6), c = 21.288(4) ? b = 93.18(2), V = 6964(2) 3, Z = 8, Dc = 1.245 g/cm3, F(000) = 2728 and m(MoKa) = 27.08 cm-1. The final R and Rw are 0.044 and 0.053 for 6765 observed reflections with I > 3.00s(I), respectively. The ytterbium atom is bonded to two terminal amide ligands with the normal YbN distances of 2.171(6) and 2.174(7) ? and two bridging amide ligands with the YbN bonds about 0.1 ?longer than those of the formers, forming a distorted tetrahedral geometry.

Synthesis and Crystal Structure of β-Diketiminate Ytterbium Dichloride

The reaction of anhydrous YbCl3 with lithium b-diketiminate, LLi (L = N,N- diphenyl-2,4-pentanediimine anion), in 1:1 molar ratio in THF gave rise to the title complex LYbCl2(THF)2 1 which has been characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pna21(#33) with a = 19.657(8), b = 9.581(4), c = 14.107(6) ? V = 2656.8(18) 3, Z = 4, C25H33N2O2Cl2Yb, Mr = 637.49, Dc = 1.594 g/cm3, F(000) = 1268.00 and m(MoKa) = 3.744mm-1. The final R and wR are 0.031 and 0.073 for 2596 observed reflections with I > 2s(I), respectively. The X-ray crystal structure analysis revealed that the center ytterbium(III) is bonded to two chloride anions, two oxygen atoms from two tetrahydrofuran molecules and one chelate ligand b-diketiminate to form a six-coordinate distorted octahedral geometry.

Oxidation Performance of Ytterbium Disilicate/Silicon Environmental Barrier Coating via Optimized Air Plasma Spraying

Environmental barrier coatings (EBCs) play a critical role in mitigating the degradation of SiCf/SiC ceramic matrix composites (CMCs) in complex combustion environment, and improve the service life of thermal engine components. In this paper, by adjusting the parameters of atmospheric plasma spraying (APS), the spraying process of ytterbium disilicate (Yb2Si2O7) under a lower power has been optimized. A two-layer EBC system consisting of ytterbium disilicate and silicon is prepared on the SiCf/SiC composite substrate by using optimized technological parameters. The thermal resistance and water oxygen corrosion resistance of such two-layer EBC system are investigated. The results indicate that the current ytterbium disilicate/silicon EBC system exhibits good phase stability, excellent water vapor and oxygen corrosion resistance. However, the exposed silicon bonding layer tends to generate an excessive thermal growth oxide (TGO) layer known as SiO2, leading to an early spallation of the coating.

Preparation of Light-Emitting Ytterbium-Doped Tantalum-Oxide Thin Films Using a Simple Co-Sputtering Method

Light-emitting ytterbium-doped tantalum-oxide thin films were prepared using a simple co-sputtering method for the first time. Sharp photoluminescence peaks having a wavelength of around 980 nm were observed from films annealed from 700&degC to 1000&degC for 10 to 40 min. The strongest intensity of the 980-nm peak was obtained from a film deposited using three ytterbium-oxide pellets and annealed at 800&degC for 20 min. Such rare-earth doped tantalum-oxide sputtered films can be used as high-refractive-index materials of autocloned photonic crystals that can be applied to novel light-emitting devices, and they will also be used as both anti-reflection and down-conversion layers for realizing high-efficiency silicon solar cells.

Synthesis and Crystal Structure of Binuclear Ytterbium Complex with Isonicotinoyl Hydrazone

The ytterbium complex of isonicotinoyl hydrazone was synthesized and the structure was determined by X-ray diffraction analysis. The crystal and molecular structure of the title complex [Yb-2(L)(3)](OH)(3) shows that the complex has two identical nine-coordinated ytterbium ions with each surrounded by N3O6 donor set, Two ytterbium ions are bridged by three phenolate oxygen atoms, The geometry around each ytterbium ions can be considered as a three-capped trigonal prism.

Investigation on Spin Hamiltonian Parameters for Tetragonal Ytterbium Center in Lutetium Orthovanadate

Rare earth doped orthovanadate crystal LuVO4∶Yb3+ shows high power laser applications because of the low quantum defect and the high thermal conductivity. Since electronic paramagnetic resonance (EPR) is a powerful tool to analyze the electronic properties and the local structures of paramagnetic impurity centers in crystals, the EPR spectra of the Yb3+ centers in LuVO4 crystal were measured recently. However, the above experimental results have not been theoretically interpreted. In this work, The EPR g factors and the hyperfine structure constants of 171Yb3+ and 173Yb3+ isotopes in LuVO4 crystal were theoretically studied from the perturbation formulae of the spin Hamiltonian parameters for 4f13 ion in tetragonal symmetry. The needed crystal parameters were obtained from the superposition model and the local structure of the studied system. The calculated results were in reasonable agreement with the observed values.

Background Absorption of Lutecium and Ytterbium Matrices in Graphite Furnace Atomic Absorption Spectrometry

The background absorption of Lu and Yb matrices was studied. The experimental results show that there is a significantly wavelength-dependent. The effects of ashing temperature, heating mode, atomization temperature, recording time and matrix modifiers affecting the non-specific absorption of Lu and Yb matrices were discussed.

Study on the Synergistic Extraction of Ytterbium with 1－Phenyl－3－Methyl－4－（α－Furoyl）－5－Pyrazolone and Neutral Extractant

The extraction of Yb3+ by HA [1-phenyl-3-methyl-4-(α-furoyl)-5-pyrazolone] and by HA in combination with a neutral extractant B in toluene have been studied, where B represents n-butyloctyl sulfoxide (BOSO), n-pentylhexyl sulfoxide (PHSO), ethyl-n-dodecyl sulfoxide (EDSO), diphenyl sulfoxide (DPSO) or TBP. The composition of the synergistic extraction complexes have been shown to be YbA3·B and their extraction equilibrium constants have been determined separately.

Density Functional Studies of the Reaction of Ytterbium Monocation with Fluoromethane:C-F Bond Activation and Electron-Transfer Reactivity

The potential energy surface and reaction mechanism corresponding to the reaction of ytterbium monocation with fluoromethane, which represents a prototype of the activation of C-F bond in fluorohydrocarbons by bare lanthanide cations, have been investigated for the first time by using density functional theory. A direct fluorine abstraction mechanism was revealed, and the related thermochemistry data were determined. The electron-transfer reactivity of the reaction was analyzed using the two-state model, and a strongly avoided crossing behavior on the transition state region was shown. The present results support the reaction mechanism inferred from early experimental data and the related thermochemistry data can provide a guide for further experimental researches.