Shift of the centers of H<Subscript>2</Subscript>O absorption lines in the region of 1.06 μm

The shift coefficients for the lines of the ν₁ + ν₂ + ν₃ and ν₂ + 2ν₃ bands of H₂O in the region from 9403 to 9413 cm^?1 are measured and calculated. The measurements are performed using an intracavity laser spectrometer based on a neodymium laser with a determination error of the line center of 0.003–0.004 cm^?1. The Ar, Kr, and Xe noble gases, as well as nitrogen, oxygen, and hydrogen were used as buffer gases. The coefficients of shifts in eight H₂O absorption lines induced by oxygen, nitrogen, and atmospheric air pressures fall into the region from ?0.004 to ?0.069 cm^?1/bar. The calculations are performed by a semiempirical method using variational wave functions, which, in contrast to other studies, correctly takes into account intramolecular interactions. The calculated values agree satisfactorily with experimental data.     

Effect of the humidity on the uptake of NO<Subscript>3</Subscript> on coatings composed of MgCl<Subscript>2</Subscript> · 6H<Subscript>2</Subscript>O and MgBr<Subscript>2</Subscript> · 6H<Subscript>2</Subscript>O and mixtures thereof with NaCl

The reactive uptake of NO₃ radicals on the surface of wetted individual X salts and of wetted X-NaCl salts (X = MgCl₂ · 6H₂O and MgBr₂ · 6H₂O) at [H₂O] = 2 × 10¹²−2 × 10¹⁵ cm⁻³ and NO₃ (4.8 × 10¹² cm⁻³) was studied using a reactor with a movable insert covered with a salt coating in combination with a mass spectrometer for monitoring the initial reactant and products. The probabilities of NO₃ uptake γ on X-NaCl binary salts as functions of the content of doping salt were determined. A parametric approximation of the experimental data was proposed, which makes it possible to quantitatively predict the extent of surface enrichment of a wetted binary salt coating in doping salt and its dependence on the humidity and the content of this salt in the binary mixture. It was established that the relative surface density σ_X of X doping salt depends on its mole fraction μ_X in the X-NaCl binary salt as σ_X = aμ_X (a = 2.2 for MgBr₂ and 13.1 for MgCl₂) over the entire humidity range covered. The contributions of the X salts to the overall uptake of NO₃ at NO₃ concentration typical of the tropospheric conditions ([NO₃] ∼ 10⁷ cm⁻³ and relative humidities of RH ≤ 20%) were estimated.     

用Na2O2-DMSO体系产生O2·的ESR研究

提出了Na₂O₂的二甲基亚砜(DMsO)/H₂O溶液中产生超氧阴离子自由基(O₂^·)的新方法,用电子自旋共振仪(ESR)可直接检测到很强的O₂^·信号,研究了反应的条件及其O₂^·信号的特性,并用该法考察了茶多酚等清除剂对于超氧阴离子自由基的清除作用。结果表明本体系是产生O₂^·的有效方法,可用于超氧阴离子自由基清除剂的研究。     

Nucleation of electroactive β-phase poly(vinilidene fluoride) with CoFe2O4 and NiFe2O4 nanofillers: a new method for the preparation of multiferroic nanocomposites

Multiferroic and magnetoelectric materials show enormous potential for technological developments. Multiferroic composites are more attractive for applications due to their enhanced properties with respect to single-phase multiferroic materials. In this paper we report on the nucleation of the electroactive β-phase of poly(vinylidene fluoride), PVDF, by the addition of CoFe₂O₄ and NiFe₂O₄ nanoparticles in order to prepare poly(vinylidene fluoride)/ferrite nanocomposite for multiferroic and magnetoelectric applications,. The dispersed ferrite nanofiller particles strongly enhance the nucleation of the β-phase of the polymer matrix. In this way, magnetoelectric polymer nanocomposites can be processed avoiding the usual α- to β-phase transformation by stretching of the polymer matrix.     

Elastic properties of TeO<Subscript>2</Subscript>–B<Subscript>2</Subscript>O<Subscript>3</Subscript>–Ag<Subscript>2</Subscript>O glasses

A series of glasses [(TeO₂) _x (B₂O₃)_1−x ]_1−y [Ag₂O] _y with x = 70 and y = 10, 15, 20, 25 and 30 mol% were synthesised by rapid quenching. Longitudinal and shear ultrasonic velocity were measured at room temperature and at 5 MHz frequency. Elastic properties, Poisson's ratio, microhardness, softening temperature and Debye temperature have been calculated from the measured density and ultrasonic velocity at room temperature. The experimental results indicate that the elastic constants depend upon the composition of the glasses and the role of the Ag₂O inside the glass network is discussed. Estimated parameters based on Makishima–Mackenzie theory and bond compression model were calculated in order to analyse the experimental elastic moduli. Comparison between the experimental elastic moduli data obtained in the study and the calculated theoretically by the mentioned above models has been discussed.     

Synthesis and Luminescent Properties of Bismuth Titanates Bi1.6HoxTi2O7 – δ and Bi1.6Mg0.1HoxTi2O7 – δ

Physics of the Solid State - Pyrochlores Bi1.6HoxTi2O7&nbsp;–&nbsp;δ and Bi1.6Mg0.1Ho xTi2O7&nbsp;–&nbsp;δ, where x = 0, 0.01, 0.05, and 0.1, and...     

Infrared absorption of O−H in thin films of hydrogenated Bi2Sr2CaCu2O8

Thin films of hydrogenated Bi₂Sr₂CaCu₂O₈ show three O–H vibrational absorption bands that shift upon deuteration with frequency ratiosv _O-H/v _O-D1.3, as expected for local modes. The band positions indicate that hydrogen atoms may be located at two different sites, namely in CuO₂ layers and, for the most part, in BiO double layers. The temperature dependences of these absorption bands give no hint of any direct interactions between the O–H vibrational modes and the superconducting phase transition.     

Adsorption of O2 and CO2 on the Si(111)-7 × 7 surfaces

The interaction of O₂ and CO₂ with the Si(111)-7 × 7 surface has been studied with X-ray photoelectron spectroscopy (XPS). It was found that both O₂ and CO₂ molecules can readily oxidize the Si(111)-7 × 7 surface to form thin oxide films. Two oxygen species were identified in the oxide film: oxygen atoms binding to on-top sites of adatom/rest atoms with an O 1s binding energy of ~ 533 eV as well as to bridge sites of adatom/rest atom backbonds at ~ 532 eV. These two oxygen species can be interconverted thermally during the annealing process. Due to the low oxidation capability, the silicon oxide film formed by CO₂ has a lower O/Si ratio than that of O₂.     

Microwave dielectric properties of the 5.5Li<Subscript>2</Subscript>O–Nb<Subscript>2</Subscript>O<Subscript>5</Subscript>–7TiO<Subscript>2</Subscript> ceramics

A new Li₂O–Nb₂O₅–TiO₂ (LNT) ceramic with the Li₂O:Nb₂O₅:TiO₂ mole ratio of 5.5:1:7 was prepared by solid state reaction route. The phase and structure of the ceramic were characterized by X-ray diffraction and scanning electron microscopy (SEM). The microwave dielectric properties of the ceramics were studied using a network analyzer. The microwave dielectric ceramic has low sintering temperature (∼1075°C) and good microwave dielectric properties of ε _r=42, Q×f=16900 GHz (5.75 GHz), and τ _f =63.7 ppm/°C. The addition of B₂O₃ can effectively lower the sintering temperature from 1075 to 875°C and does not induce degradation of the microwave dielectric properties. Obviously, the LNT ceramics can be applied to microwave low temperature-cofired ceramics (LTCC) devices.     

Ionized physical vapor deposited Al2O3 films: Does subplantation favor formation of α‐Al2O3?

The broad energy distributions of the condensing particles typically encountered in ion assisted vapor deposition techniques are often a drawback when attempting to understand the effect of the energetic bombardment on the film properties. In the current study, a monoenergetic Al⁺ beam generated by a filtered cathodic arc discharge is employed for the deposition of alumina (Al₂O₃) films at well defined Al⁺ ion energies between 4 eV and 200 eV at a substrate temperature of 720 °C. Structural analysis shows that Al⁺ energies of 40 eV or larger favor the formation of the thermodynamically stable α‐Al₂O₃ phase at the expense of other metastable Al₂O₃ polymorphs. The well defined ion energies are used as input for Monte‐Carlo based simulations of the ion–surface interactions. The results of these simulations reveal that the increase of the Al⁺ ion energy leads to an increase in the fraction of ions subplanted into the growing film. These findings underline the previously not considered role of subsurface processes on the phase formation of ionized physical vapor deposited Al₂O₃ films. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the accurate determination of pressure- induced line shifts in the 2ν<Subscript>3</Subscript> band of H<Subscript>2</Subscript>O at 1320 nm

A simple technique is demonstrated for the accurate determination of pressure-induced line shifts of water in air. High- and low-pressure water samples are simultaneously probed on selected overtone transitions at 1.32 μm using a current-modulated distributed-feedback diode laser and harmonic detection. The resultant profiles yield an average line shift of -293±30 MHz/atm for the 3,3,0 (002)2,2,1 (000)transition at 227251 GHz and -134±7 MHz/atm for the 3,2,1 (002)2,1,2 (000) transition at 227027 GHz. Comparisons are made between first- and second-harmonic detection, and wavelength- and frequency-modulation regimes. The effect of modulation broadening on the returned line shifts is quantified. Received: 12 August 2002 / Revised version: 21 October 2002 / Published online: 8 January 2003 RID="*" ID="*"Corresponding author. Fax: +44-01865/275410, E-mail: gus.hancock@chemistry.ox.ac.uk     

The role of structural and nonstructural water in oxyfluoride K<Subscript>2</Subscript>WO<Subscript>2</Subscript>F<Subscript>4</Subscript> · H<Subscript>2</Subscript>O

X-ray structural and polarization optical investigations have been performed, and birefringence and rotation angles of the optical indicatrix φ _b and φ _c of the K₂WO₂F₄ · H₂O crystal have been measured in the temperature range of 100–600 K. The structure and symmetry of compounds at room temperature have been refined. It has been established that the layered crystal K₂WO₂F₄ · H₂O can exist in two states (A and B) depending on the atmospheric humidity and undergoes the sequence of reversible and irreversible phase transformations G ₃ ↔ G ₂ → G ₁ → G ₀. The sequences of changes in the phase symmetry P [`1]\bar 1 ↔ C2/m → P4/nmm for samples A and m ↔ C2/m → P4/nmm for samples B have been found. The second-order proper ferroelastic phase transition (P [`1]\bar 1 ↔ C2/m) at T ₀₃ = 270–290 K (G ₃ ↔ G ₂) is accompanied by twinning and appearance of the shift deformation x ₆. The crystal system of the substance for the B crystals remains invariable after the second-order phase transition G ₃ ↔ G ₂. The irreversible first-order phase transition G ₂ → G ₁ occurs in a temperature range T ₀₂ ≈ 350–380 K; it is accompanied by the loss of the crystallization water, which then is reduced easily from the atmosphere for a day. The substance decomposes at T ₀₁ ≈ 510 K (G ₁ → G ₀). The distinction between the A and B crystals has been explained by the presence or absence of free water in interlayer spacings.     

The differentiation of elementary polarizations of FeF<Subscript>3</Subscript>·3H<Subscript>2</Subscript>O/C cathode material in LIB

Time-dependent elementary polarizations of FeF₃·3H₂O/C cathode material were quantitatively investigated in dc polarization in order to determine the key factors that comprise the total polarization. The measurement of electrochemical impedance spectrum at a given state of charge and the subsequent least square fitting of its equivalent circuit allow the calculation of elementary contributions of individual kinetic step to the total polarization. The profiles of the calculations were well consistent with those of experiments based on the same states of charge, and the elementary contributions could be differentiated successfully which reveal that the solid-state diffusion process makes the largest contribution to the total polarization after 2.5 s discharge beginning with open-circuit voltage (OCV) level 3.5 V. The results may be helpful for the design of batteries of better performance with FeF₃ cathode.     

Reactions of initiation of the autoignition of H<Subscript>2</Subscript>–O<Subscript>2</Subscript> mixtures in shock waves

The initiation of the autoignition of hydrogen–oxygen–argon mixtures behind reflected shock waves is studied by absorption and emission spectrophotometry in the temperature range of 960 < T < 1670 K at pressures of ~0.1 MPa. Introduction of Mo(CO)₆ additive in an amount of ~80 ppm made it possible to study the effect of O atoms on the shortening of the ignition delay time of H₂–O₂–Ar mixtures. A kinetic modeling of our own and published experimental data at temperatures of 930 < T < 2500 K and pressures of 0.05 < P < 8.7 MPa enabled to establish how the initiation reactions influence the process of self-ignition and to evaluate the rate constant for one of the initiation reactions: k(H₂ + O₂ → 2OH) = (3 ± 1) × 10¹¹exp(–E _a/RT), cm³ mol^–1 s^–1, where E _a = (40 ± 2) kcal/mol.     

Evaluation of the electrical capacitance of M,O2/O2− interfaces (M=Pt, Au, Pd, In2O3; O2− = zirconia based electrolyte) exhibiting constant phase element behavior

The behavior of the electrode systems M,O₂/O² (M = porous Pd, Pt, A and dense In₂O₃; O²⁻ = ZrO₂-based single-crystal solid electrolyte) was studied by means of impedance measurements. The examination of the Pt,O₂/O²⁻ electrode system showed that the constant phase element (CPE) can be attributed to a nonuniform distribution of current at the electrode surface. It was observed that the CPE parameters n and B in the expression Y_CPE = B (jω)ⁿ may be related by B=(C_dl)ⁿ (R_Ω)_n-1, where C_dl is the double layer capacitance and R_Ω the resistance of the electrolyte in the cell. Then, C_dl of the electrode - electrolyte interface could be determined. The specific C_dl of the oxidized noble metals and india electrodes is nearly one order of magnitude lower than C_dl of the electrodes in the metallic state. The C_dl value of all the electrodes studied depends little or is independent of temperature and oxygen pressure. It is concluded that the Helmholtz model of double layer structure does not contradict the C_dl behavior.     

Fluorescent Property of the Gd<Superscript>3+</Superscript>-Doped Terbium Complexes and Crystal Structure of [Tb(TPTZ)(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>]Cl<Subscript>3</Subscript>·3H<Subscript>2</Subscript>O

The complex of Tb(TPTZ)Cl₃·3H₂O was synthesized by adding the ethyl alcohol solution of TbCl₃ (1 mmol) to the solution of 2,4,6-tris-(2-pyridyl)-s-triazine(TPTZ,1 mmol) with constant stirring. The solution which had been filtered was kept at the room temperature for 4 weeks, and then a kind of transparent crystal was formed. Besides, nine kinds of solid complexes in the different molar proportion of terbium to gadolinium had been synthesized by adopting the similar method mentioned above. It was inferred from the elemental analysis and rare earth complexometry that the composition of these complexes is (Tb_xGd_y)(TPTZ)Cl₃·3H₂O (x : y = 0.9 : 0.1, 0.8 : 0.2, 0.7 : 0.3, 0.6 : 0.4, 0.5 : 0.5, 0.4 : 0.6, 0.3 : 0.7, 0.2 : 0.8, 0.1 : 0.9). The absorption spectra and photoluminescence of the complexes were determined in dimethylsulfoxide (DMF), which showed that the excitation of the complexes is mostly ligand based. The triplet state energy level of TPTZ was measured, indicating that the lowest excitation state energy level of Tb(III) and the triplet state energy level of TPTZ match well each other. The fluorescent data indicated that the fluorescent emission intensity of Tb³⁺ ions would be enhanced in the complexes after terbium was doped with Gd³⁺ ion. When x : y was 0.5 : 0.5, the fluorescent emission intensity was the largest. The result obtained by testing the X-ray diffraction of the monocrystal revealed that the molecular formula of the mono-crystal complex is [Tb(TPTZ)(H₂O)₆]Cl₃·3H₂O. The number of metal ion coordinates is nine, and the tridentate TPTZ and six water molecules are bonded with terbium respectively. Besides, it also revealed that the monocrystal belongs to the monoclinic system, and space group Cc with the following unit cell parameters is a = 1.4785 (3) nm, b = 1.0547 (2) nm, c = 1.7385 (4) nm, β = 94.42 (3)°, V = 2.7028 (9) nm³ and Z = 4.     

Crystallization of WO<Subscript>3</Subscript>·H<Subscript>2</Subscript>O nanosheets with high-adsorption capacity for methylene blue

Square sheet-like WO₃·H₂O have been efficiently synthesized via chemical precipitation route. The as-synthesized WO₃·H₂O nanosheets have fast adsorption rate and high-adsorption capacity for methylene blue (MB) removal from aqueous solution, which is attributed to plenty of O-H functional groups and {101} exposed facet effect. The as-synthesized material can be easily renewed via photodegradation under UV light irradiation after MB adsorption.

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Graphical abstract WO₃·H₂O nanosheets, which can be easily renewed after MB adsorption via photodegradation, are synthesized by a facile ion-exchange route and exhibit excellent adsorption performance on MB.

     

The role of surface hydroxils of Al2O3·xH2O in the luminescence of adsorbed fluorescein molecules

Acta physica Academiae Scientiarum Hungaricae - Producing various surface hydroxil concentrations on Al2O3 films by surface reactions it was found that there is a distinct relation between the...