The results of development of physicochemical fundamentals for the synthesis and deep purification of tin tetrachloride have been described. The samples of SnCl
4
have been prepared from elements in ...a specially designed quartz installation. Prepared SnCl
4
has been purified by rectification on a perforated-plate column. It has been revealed by mass spectrometry that the content of lead admixture after SnCl
4
rectification decreases from 120 to 2 ppm, and the content of admixtures of other metals decreases considerably. Separation factors in liquid–vapor system for hardly separable admixtures have been calculated. The purity of SnCl
4
samples has been confirmed by IR and Raman spectroscopy. The prepared SnCl
4
samples contained 10
–4
wt % of admixtures.
Synthesis of anhydrous cerium tetrafluoride Brekhovskikh, Maria N.; Vaimugin, Leonid A.; Moiseeva, Liudmila V. ...
Journal of fluorine chemistry,
April 2024, 2024-04-00, Letnik:
275
Journal Article
Recenzirano
•A procedure for the synthesis of the anhydrous CeF4 by the reaction between CeF3 and XeF2 was proposed.•Characterization of the forming CeF4 was carried out by XRD, FTIR, 19F NMR and ...thermogravimetry.•The anhydrous CeF4 was found to undergo hydration when exposed to air.•An approximate formula CeF4•0.2H2O*0.7H2O for the crystalline hydrate, formed after exposure to air, was proposed.
By reacting CeF3 with XeF2 the anhydrous CeF4 was synthesized and studied by XRD, SEM, FTIR, 19F NMR spectrometry and thermogravimetry. It was found that CeF4 undergoes hydration upon keeping in air forming the crystalline hydrate with the approximate formula CeF4•0.2H2O*0.7H2O. Water molecules both enter the coordination sphere of cerium and form crystalline hydrates with cerium(IV) fluoride due to OH…F hydrogen bonds in the crystal lattice.
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We have studied EPR spectra of MnO
2
-activated fluorozirconate and fluorohafnate glasses in order to determine the oxidation state and distribution of the manganese ions. The effect of activator ...concentration on the ratio of the percentage of free Mn
4+
ions to that of ions in clusters in the glasses has been investigated for the first time. The results demonstrate that, at high activator concentrations, the manganese ions in the glasses are clustered, and only a small fraction of them are present as isolated ions. Reducing the manganese concentration leads to an increase in the percentage of free Mn
4+
ions. Devitrification is accompanied by dissociation of the clusters and a transition of the ions to an isolated state.
Recent results from OKA setup concerning form factor studies in Ke3 decay are presented. About 5.25 M events obtained for decays of 17.7 GeV/cK+ are selected for the analysis. The linear and ...quadratic slopes for the decay form factor f+(t) are measured: λ'+ = 2.95 ± 0.022 ± 0.018 × 10 -2 for the linear slope fit and λ+ = 2.611 ± 0.035 ± 0.028 × 10 -2, λ"+ = 1.91 ± 0.19 ± 0.14 × 10 -3 for the quadratic one. The scalar and tensor contributions are compatible with zero. Several alternative parametrizations are tried: the Pole fit parameter is found to be MV = 891 ± 3 MeV; the parameter of the dispersive parametrization is measured to be Λ+ = 2.458 ± 0.018 × 10-2.
Judd–Ofelt(J–O) analysis of Er3+:K2YF5 crystals has been performed to evaluate the spontaneous emission probabilities, radiative lifetimes and luminescence branching ratios for Er3+ions from the ...viewpoint of developing novel laser materials. The derived J–O parameters are Ω2=1.216, Ω4=0.647 and Ω6=0.459×10−20cm2 for a K2Y0.9Er0.1F5 crystal. Radiative lifetimes of the 4I13/2and 4I11/2 states are as long as 14.9ms and 17.4ms, respectively. Stimulated-emission cross-sections spectra are presented for the 4S3/2→4I15/2, 4I13/2→4I15/2 and 4I11/2→4I13/2 transitions. The maximum σSE values are 1.5×10−20cm2 at 558nm, 0.72×10−20cm2 at 1531nm and 0.40×10−20cm2 at 2705nm,respectively. Non-radiative relaxation rates have been determined for the excited-states of Er3+ions in K2YF5. It is assumed that Er3+:K2YF5 crystals are promising for green up-conversion lasers.
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We have studied luminescence and electron paramagnetic resonance (EPR) spectra of manganese- and europium-activated fluorozirconate glasses in the ZrF
4
–BaF
2
–LaF
3
–AlF
3
–NaF (ZBLAN) system and ...fluorohafnate glasses in the HfF
4
–BaF
2
–LaF
3
–AlF
3
–NaF (HBLAN) system in order to assess the oxidation state and spatial distribution of the activator ions. The manganese luminescence band has been shown to shift from the green (545 nm) to the red (610 nm) spectral region, and additional lines in the EPR spectrum of manganese have been observed to emerge in the EPR spectrum of manganese as a result of BaCl
2
substitution for BaF
2
in the ZBLAN glass. The ratio of the concentration of free activator ions to that of clustered ions has been estimated quantitatively. It has been shown that, at high doping levels, the manganese and europium ions in the glasses are predominantly clustered, and only a small part of them are present as isolated ions.
The concentrations of macrocomponents (Na, K, Mg, Ca, and P) and trace elements (Rb, Cs, Be, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Pb, Cd, Ag, Sn, Sb, Al, Ga, rare earth elements, Ti, Zr, Hf, Th, U, Nb, ...Ta, B, V, Cr, Ge, As, Mo, and W) were measured in 12 macrophyte species selected in the freshwater part of the Volga mouth area. Close correlations between the average specific contents were established: (a) most of the studied trace elements, which confirms the phenomenon of group concentration found earlier for heavy metals and chromium; (b) magnesium, calcium, and trace elements capable of their isomorphic substitution; (c) the typically biogenic elements potassium and phosphorus. A regular increase in the concentrations of trace elements and, to a lesser extent, of magnesium and calcium was found in the series “helophytes → large-leaved hydrophytes → variegate-leaved hydrophytes → small-leaved hydrophytes, including hydrophytes completely immersed in water,” which corresponds to an increase in the effective surface area of plants in the aquatic environment.
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This paper summarizes results of studies aimed at developing physicochemical and scientific methodological principles of the preparation of high-purity substances by integrated technological ...processes. We rely on the identification and chemical transformations of impurities in the recovery from raw materials, synthesis, and ultrapurification of substances by various methods. A scientific methodological approach has been developed for choosing and substantiating integrated processes for the preparation of extrapure-grade (6N or 7N) compounds with a total content of trace impurities from 0.1 to 1 ppm by weight from standard and unconventional raw materials. We have obtained batches of high-purity arsenic- and gallium-containing substances and tested them in the technology of advanced microelectronic and optical materials.
Study of the Viscosity of Arsenic Acid Solutions Fedorov, V. A.; Menshchikova, T. K.; Nikonov, K. S. ...
Theoretical foundations of chemical engineering,
10/2023, Letnik:
57, Številka:
5
Journal Article
Recenzirano
To optimize the processes of obtaining high-purity arsine and elemental arsenic by the electrochemical method, the dynamic viscosity is calculated and the kinematic viscosity is measured in solutions ...of arsenic acid formed by the electrolysis of a solution of hydrolytic sodium arsenite, the main product of the destruction of lewisite, in a temperature range of 20–80°C and a wide concentration range of 20–74 wt %.
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