Effect of ionic liquids on the extraction of Am from HNO3 solutions with diphenyl(dibutylcarbamoylmethyl)phosphine oxide in dichloroethane

Addition of small (1?C5 vol %) amounts of ionic liquids (ILs) increases the Am(III) distribution ratio in the system with diphenyl(dibutylcarbamoylmethyl)phosphine oxide (Ph₂Bu₂) by more than 2 orders of magnitude. With 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C₄mim]⁺Tf₂N^?) used as IL, the Am(III) extraction is possible even from 8 M HNO₃, which is important in radiochemical analysis of process and environmental samples, because many procedures are based on the transfer of solid samples into 8 M HNO₃. The extraction data show that the extractable Am(III) complex contains three Ph₂Bu₂ ligands, an IL anion, and two NO ₃ ^? anions.     

Non-polymeric binders for ceramic powders: utilization of neutral and ionic species derived from decaborane(14)

The pyrolytic conversion of bis-Lewis base adducts of decaborane(14), L·B₁₀H₁₂·L (L=neutral monophosphine) and phosphonium salts of the [B₁₀H₁₀]^2– anion (e.g. [Ph₄P⁺]₂, etc.), to ceramic materials has been studied. All species examined served as binders for a variety of non-oxide refractory ceramic powders (e.g. B₄C, BN, BP, B₁₃P₂, SiC, Si₃N₄, B, C, AIN).     

Cathodic reduction of FeOCl in organic electrolytes

Well defined members of a nonstoichiometric family of intercalation complexes M_x(DMSO)_y(Fe⁺³_1?xFe⁺²_xOCl) have been obtained by cathodic reduction of FeOCl in $\text{DMSO}\text{M}{}^{\mathrm{+}}$ solutions. From galvanostatic measurements upper limits for x have been determined with x ≈ 0.1 for M⁺ = Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, x ≈ 0.5 for H⁺ and x ≈ 0.05 for (CH₃)₄N⁺ and (C₄H₉)₄N⁺. Correlations between degree of reduction (x), ionic radii of M⁺, amount of intercalated DMSO (y), basal spacings and M⁺ coordination are discussed.     

Generation of nitrogen beams with very high N/N2 ratio using hollow cathode discharge

Nitrogen beams with very high N⁺/N₂⁺ ratio were generated using hollow-cathode discharge. The dependence of N⁺/N₂⁺ ratio in the extracted beams on the discharge parameters was studied by mass spectroscopy. Very high N⁺ fractions (up to 90% and the maximum is about 98%) can be easily achieved without mass separation under typical operating conditions. The extracted beams with discharges using mixture precursors, such as N₂/NH₃, or N₂/Ar were also investigated.     

The study of graphite disordering using the temperature dependence of ion-induced electron emission

The temperature dependences of ion-induced electron emission yield γ(T) under 6-30 keV N₂⁺, Ne⁺, Ar⁺ and 15 keV N⁺ high-fluence ion irradiation of polycrystalline graphite at normal ion incidence have been analyzed to trace the structure change dependence depending on irradiation temperature and the level of radiation damage v measured in dpa (displacements per atom). It has been found that, under irradiation at room temperature, the threshold value for graphite lattice disordering equals v_d ≈ 60 dpa for noble gas ions (Ar⁺, Ne⁺) and ν_d ≈ 40 dpa for N₂⁺.     

Ion probe technique for the study of gallium diffusion in silicon nitride films

The penetration of Ga in films of amorphous Si₃N₄ about 2000 Å thick on Si substrates has been studied. The films were produced by pyrolysis. Diffusion profiles were obtained by surface exposure to Ga vapor, and the implantation profiles by ion bombardment in an isotope separator. Evaluation of the profiles was effected by means of sputtering in a secondary ion microanalyzer. For depth calibration, ion yield profiles of ⁶⁹Ga⁺ of ⁷¹Ga⁺ were compared with the profiles of ³⁰Si⁺, ⁷⁰(Si₂N⁺, SiN⁺₃) and ⁷²Si₂O⁺. The integration of implantation peaks furnished a means of obtaining absolute values of Ga concentrations from the secondary ion intensities. Hence the surface concentration of vapor-deposited Ga at 1100°C was assessed to be of the order of 8 × 10²⁰ atoms cm^-3. The diffusion coefficient of Ga in Si₃N₄ at 1100°C was found to be about 5 × 10^-17 cm² s^-1. The method, which combines sputtering and mass spectrometry, appears to be applicable for measuring diffusion coefficients in this system down to about 3 × 10^-18 cm² s^-1.     

Mass spectrometric investigations of background gases during the sputtering of tantalum

The time dependence of the partial pressures of H⁺₂, O⁺₂, CH⁺₄, H₂O⁺, N⁺₂ and a combination of CO⁺ and C₂H⁺₄ have been monitored continuously during and after the sputtering of Ta. With the exception of O⁺₂, these components undergo a transient increase on initiation of sputtering. The increase in the background CH⁺₄ is attributed to desorption and dissociation of heavier hydrocarbons by the discharge. This CH₄ may itself be dissociated, thus contributing to the increase in the background H₂ partial pressure. H₂ is also produced by the desorption and dissociation of H₂O. The background oxygen partial pressure is reduced by a factor of five during sputtering. An oxygen exposure of 1 × 10² Langmuir produces about one monolayer of oxide on sputtered Ta. For films reactively sputtered in oxygen the resistivity decreases as the lenght of the baking cycle prior to sputtering is increased. This shift with baking time may be attributed to a decrease in the quantity of water vapour desorbed by the discharge, and thus a decrease in the total oxygen concentration in the films.     

Longitudinal and lateral distributions of medium energy heavy ions in some semiconductor films

The depth distributions of Bi⁺ and Fe⁺ ions implanted into SiN_1.375H_0.603, α-Si, Si₃N₄ and SiO₂ films at different angles were measured by Rutherford backscattering technique. The results show that: (1) the experimental mean projected range R_p is in agreement with the calculated value by TRIM'98 within 9% for SiN_1.375H_0.603, Si₃N₄ α-Si cases; (2) the experimental range straggling ΔR_p is larger than the calculated value by TRIM'98, the reason is not known; and (3) the depth distributions of implanted ions at different angles in all cases exhibit nearly Gaussian behaviour; the agreement of the extracted lateral spread with the calculated value is best for the case of Bi⁺ ions implanted into SiO₂.     

Time and energy resolved ion mass spectroscopy studies of the ion flux during high power pulsed magnetron sputtering of Cr in Ar and Ar/N2 atmospheres

Mass spectroscopy was used to analyze the energy and composition of the ion flux during high power pulsed magnetron sputtering (HIPIMS/HPPMS) of a Cr target in an industrial deposition system. The ion energy distribution functions were recorded in the time-averaged and time-resolved mode for Ar⁺, Ar²⁺, Cr⁺, Cr²⁺, N₂⁺ and N⁺ ions. In the metallic mode the dependence on pulse energy (equivalent of peak target current) was studied. In the case of reactive sputtering in an Ar/N₂ atmosphere, variations in ion flux composition were investigated for varying N₂-to-Ar flow ratio at constant pressure and HIPIMS power settings. The number of doubly charged Cr ions is found to increase linearly with increasing pulse energy. An intense flux of energetic N⁺ ions was observed during deposition in the reactive mode. The time evolution of ion flux composition is analyzed in detail and related to the film growth process. The ionization of working gas mixture is hampered during the most energetic phase of discharge by a high flux of sputter-ejected species entering the plasma, causing both gas rarefaction and quenching of the electron energy distribution function. It is suggested that the properties (composition and energy) of the ion flux incident on the substrate can be intentionally adjusted not only by varying the pulse energy (discharge peak current), but also by taking advantage of the observed time variations in the composition of ion flux.     

Catalytic Reduction of U(VI) with Hydrazine and Formic Acid in HNO3 Solutions

Catalytic reduction of 0.75 M U(VI) with hydrazine in HNO₃ solutions was studied under various conditions. At 58°C up to 0.55 M U(IV) is accumulated within 2 h in solutions containing 1-1.5 M N₂H₅ ⁺ and 2 M HNO₃ in the presence of 1% Pt/SiO₂ (S : L = 1 : 10). The reduction is decelerated with decreasing N₂H₅ ⁺ concentration to 0.75 M or with increasing HNO3 concentration to 3-4 M. 1.2 mol of U(IV) is formed per mole of oxidized hydrazine. Uranium(VI) reduction with formic acid in the presence of 1% Pt/SiO₂ and 1% Pt/VP-1An anion exchanger was studied. There exists a threshold N₂H₅ ⁺ concentration below which U(VI) is not reduced. The reduction in solutions containing 1-2 M HCOOH, 1-2 M HNO₃, and 0.1 M N₂H₅ ⁺ is faster than in solutions free of formic acid and containing 1-1.5 M N₂H₅ ⁺.     

High-pressure investigations of positive ion-molecule reactions in a mixtureof H2S and CH4

The positive ion-molecule reactions in the mixtures of hydrogen sulfide and methane have been examined by means of quadrupole mass spectrometer with the high-pressure ion source. The concentration of hydrogen sulfide in mixtures ranged from 10% to 90% with 10% increment. For each mixture major bimolecular ion-molecule reactions have been identified in the total pressure range from 0.7 to 33.3 Pa. The electron energy for all measurements was fixed at 300 eV and the repeller potential was maintained at 5 V. Relative intensities of ion currents for the observed ions C⁺, CH⁺, CH₂⁺, CH₃⁺, CH₄⁺, CH₅⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, S⁺, HS⁺, H₂S⁺, H₃S⁺, H₃³⁴S⁺, CHS⁺, CH₃S⁺, S₂⁺, HS₂⁺ and H₂S₂⁺ were determined as a function of total gas pressure inside the ion source collision chamber, repeller potential and concentration of methane in the mixture.     

Potentials of internuclear interaction of diatomic molecules in planetary atmosphere

A method is given for the calculation of Ridberg—Klein—Rees potentials (RKR potentials) of internuclear interaction of diatomic molecules, which is based on a combination of numerical and analytical computer codes. A calculation of potentials of internuclear interaction is performed for 32 electron states of N₂, N ₂ ⁺ , C₂, CO, CO⁺, and CN molecules of practical interest as regards problems in aerophysics of interplanetary space vehicles. Complete spectral information is given for the calculation of potential curves, which may be used for unique comparison of the results of calculations of internuclear potentials obtained by different methods.     

Vaporization of (SN)x and TTF-TCNQ

The vaporization of (SN)x was studied by electron impact and chemical ionization mass spectrometry. Comparison of the spectra with those of S₄N₄ suggests that vaporization generates an unstable, acyclic S₄N₄ which subsequently fragments to a cyclic S₃N₃⁺ and SN⁺ ion in the mass spectrometer. Mass spectrometry may be used to analyze (SN)x for S₈ and cage S₄N₄. Vaporization of TTF-TCNQ produced the component donor and acceptor molecules.     

Tunable Afterglow and Self-Trapped Exciton Emissions in Zr (IV)-Based Organic–Inorganic Metal Halide Hybrids by Metal-Ion Doping

Low-dimensional hybrid metal halide (LDHMH) materials have attracted considerable attention owing to their intriguing optical properties. To the best of the knowledge, this is the first study to successfully demonstrate both self-trap exciton (STE) and afterglow emissions in Zr-based LDHMH materials. The obtained pure (Ph₃S)₂ZrCl₆ crystals showed near-ultraviolet phosphorescence and a green afterglow owing to the organic cation Ph₃S⁺, while the Bi-doped and Sb-doped crystals exhibited both STE and afterglow emissions. However, the Te-doped crystals showed only a broad yellow STE emission owing to the [TeCl₆]²⁻ octahedron. In addition, all the crystals showed good stability. Notably, Sb-doped crystals produced white light, which can be adjusted between cold white and warm white using different excitations. Finally, this strategy for both STE and afterglow emissions can be applied to other LDHMH materials for optical applications.     

Synthesis and X-ray Diffraction Study of Mixed-Metal Orthophosphates with NaZr2(PO4)3 and CePO4 Structures

Mixed-metal orthophosphates with Ca^{2 +}, Cd^{2 +}, Gd^{3 +}, Ti^{4 +}, Hf^{4 +}, Ce^{4 +}, U^{4 +}, and Pu^{4 +} were synthesized and studied by X-ray diffraction. Crystalline compounds containing cerium or plutonium, or both these elements were prepared. Cerium was taken as an imitator for plutonium. The phosphates containing Ti^{4 +} and Hf^{4 +} formed two-phase systems. One of the phases was assigned to the Zr₂(PO₄)₃ structural type (NZP), and the other phase, to the CePO₄ type (monazite). In the other cases, single-phase products were formed. The effect of the cationic composition on the crystal structure of the complex orthophosphates, including the unit cell parameters of the crystalline phases, was studied.     

Ion–molecule reactions in mixtures of ethane with carbon tetrafluoride

Ion–molecule reactions have been measured for the ethane–carbon tetrafluoride mixtures of different compositions using a quadrupole mass spectrometer with a high-pressure ion source. Concentration of ethane in these mixtures ranged from 10% to 90% (at 10% increment). The following primary and secondary ions: CH₃⁺, F⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, C₂H₆⁺, C₃H₅⁺, C₃H₇⁺, C₄H₇⁺, C₄H₉⁺, C₄H₁₀⁺, C₄H₁₁⁺ and CF₃⁺ were observed. Relative ion current intensities for primary and secondary ions are presented as a function both of total mixture pressure and concentration of carbon tetrafluoride in the mixture. Primary ions were produced by electrons with the energy of 300 eV. Potential of repeller electrode inside the ion source collision chamber was fixed at 5 V for all measurements. The total mixture pressure was changed from 0.7 to 26.6 Pa. Schemes of ion–molecule reactions were proposed.     

Charge-Assisted Hydrogen-Bonded Organic Frameworks with Inorganic Ammonium Regulated Switchable Open Polar Sites

Surface open polar sites within the voids of porous molecular crystals define the localized physicochemical environment for critical functions such as gas separation and molecular recognition. This study presents a new charge-assisted hydrogen bonding (H-bonding) motif, by exploiting inorganic ammonium (NH₄⁺) cations as H-bond donors, to regulate the assembly of C₂-symmetric carboxylic tectons for building robust H-bonded frameworks with permanent ultra-micropores and open oxygen sites. Diverse building blocks are bridged by tetrahedral NH₄⁺ to expand distinctive H-bonded networks with varied pore architectures. Particularly, the open polar oxygen sites can be switched by altering NH₄⁺ sources to tune the deprotonation of carboxyl-containing tectons. The activated porous PTBA·NH₄·DMF preserves the pore architecture and open polar oxygen sites, exhibiting remarkably selective sorption of CO₂ (107.8 cm³ g⁻¹,195 K) over N₂ (11.2 cm³ g⁻¹, 77 K) and H₂ (1.4 cm³ g⁻¹, 77 K).     

Influence of repeller potential on ion-molecule reactions in methane and carbon tetrafluoride mixtures

Investigations of ion-molecule reactions were performed for methane-carbon tetrafluoride mixtures of different compositions. Concentration of methane in these mixtures ranged from 10% to 90% (at 10% increment) and total mixture pressure was fixed at 13.3 Pa. Measurements were made using a quadrupole mass spectrometer with a high-pressure ion source. Primary ions CH₄⁺, F⁺, CF⁺ and CF₃⁺ were produced by electrons with energy of 300 eV. Secondary ions CH₅⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, C₂H₇⁺ and CF₃⁺ were observed as the result of ion-molecule reactions.The influence of repeller potential on ion-molecule reactions efficiency was examined.     

Optical emission spectroscopy study for nitrogen-acetylene-argon and nitrogen-acetylene-helium 100 kHz and dc discharges

The optical emission spectroscopy was applied to investigate the middle frequency (100 kHz) and dc low pressure discharges, generated in the nitrogen-acetylene-argon and nitrogen-acetylene-helium mixtures, commonly used for deposits of carbon nitride thin layers. Changes in the emission intensities of the selected species: CN, CH, C, H, N₂, N₂⁺ as well as Ar, Ar⁺ and He, were studied as a function of the discharge current. Excitation processes occurring in the presence of argon and helium were compared and discussed. The N₂-C₂H₂-Ar and N₂-C₂H₂-He plasmas generated in the 100 kHz and dc glow discharges were characterized by the excitation (Ar, He, H), vibrational (CN, N₂) and rotational (CN, N₂⁺) temperatures. A significant deviation from the equilibrium state was observed for the plasma containing argon as well as helium.