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1.
The enthalpy stability of the LaCl 4 ? and LuCl 4 ? ions is assessed using high-temperature mass spectrometry. The enthalpy of Cl? detachment is determined to be ΔrH0(298.15 K) = 332 ± 10 kJ/mol for LaCl 4 ? and 359 ± 10 kJ/mol for LuCl 4 ? . 相似文献
2.
Yu. A. Barbanel’ R. B. Dushin V. V. Kolin V. P. Kotlin L. G. Mashirov S. N. Nekhoroshkov 《Radiochemistry》2007,49(3):237-240
The absorption spectra of the NpO 2 + (5f 2) ion were examined in the region of the 3H 5 ← 3 H 4 magnetic dipole transition (1530–1760 nm) for series of melts with the UO 2 2+ concentration varied in the opposite directions: (1) NaCl-2CsCl eutectic melt with growing additions of the Cs2UO2Cl4 complex salt and (2) Cs2UO2Cl4 melt with growing additions of the NaCl-2CsCl mixture. Measurements of the integrated intensities of the bands belonging to the NpO 2 + ·UO 2 2+ complex and unbound NpO 2 + throughout the UO 2 2+ concentration range examined (up to 4.4 M in neat Cs2UO2Cl4 melt) and processing of the data obtained in terms of the mass action law showed that the formation-decomposition reaction of the cation-cation complex can be described adequately only using the equation of reaction in the form NpO2Cl 4 3? + UO2Cl 4 2? ? {Cl4ONpO?UO2Cl3}4? = Cl? (with the equilibrium constant of 1.3±0.1). Thus, the formation of the cationcation complex should be treated as replacement of chloride ion in the equatorial plane of uranyl(VI) by neptunyl(V), rather than as simple addition of UO 2 2+ to NpO 2 + . The reverse reaction, decomposition of the cation-cation complex, consists essentially in replacement of neptunyl(V) by chloride ion. 相似文献
3.
M. M. Kasumov 《Technical Physics Letters》2010,36(10):895-898
The mass spectrum of the products of arc discharge in helium between graphite electrodes has been studied for various values
of the gas flow rate. As the gas flow rate increases, the intensity of C60±, C70±, C84± and C90± fullerene peaks increases and that of the C2− and C3+ cluster radicals decreases, but the total decay in radicals amounts to only 21% of the total growth of fullerenes. From this
it follows that a contribution to the formation of fullerenes from the neutral clusters (which are taken into account for
the first time) significantly exceeds the contribution due to small radical species. 相似文献
4.
O. P. Krivoruchko T. V. Larina V. F. Anufrienko I. Yu. Molina E. A. Paukshtis 《Inorganic Materials》2009,45(12):1355-1361
We have synthesized nanoparticulate cobalt(II) hydroxide containing Co2+ in tetrahedral oxygen coordination (Co Td 2+ ), atypical of such systems: nano- [Co(OH)2(H3O) δ + ]δ+. The (Co Td 2+ ) coordination in the hydroxide is inferred from its electronic diffuse reflectance spectrum, which shows a multiplet of strong absorption bands at 14500, 15000, and 16000 cm?1 (4 A 2(F)-4 T 1(P) transition). Nanoparticulate cobalt(II) hydroxide forms in a weakly acidic medium under essentially nonequilibrium conditions due to supersaturation (by three to four orders of magnitude) with the starting reagents (CoCl2 and LiOH) at the instant of the formation of the poorly soluble phase Co(OH)2. Presumably, colloidal particles of nanoparticulate cobalt(II) hydroxide in a weakly acidic aqueous medium have a positive surface charge, compensated by a counter-ion (Cl?) layer: nano-[Co(OH)2(H3O) δ + ]δ+ · δCl?. The XRD patterns of pastes (gels) containing this hydroxide show three broad-ened lines with d = 5.31 (2θ = 16.7°), 2.77 (2θ = 32.3°), and 2.32 Å (2θ = 38.8°). According to small-angle X-ray scattering data, nano-[Co(OH)2(H3O) δ + ]δ+ has a narrow particle size distribution (1.0–2.0 nm). Synthesis and storage conditions are identified which ensure stabilization of the electronic state and particle size of nano-[Co(OH)2(H3O) δ + ]δ+ for a long time. 相似文献
5.
A spectrophotometric study showed that, in 5 M NaOH, Pu(VII) prepared by ozonation of Pu(VI) is reduced with excess K4Fe(CN)6. The Pu(VII) content can be estimated from the amount of the Fe(CN)63− formed. In NaOH solutions of concentration exceeding 8 M, the Fe(CN)63− ion oxidizes Pu(VI). In 10.3 M NaOH, the tenfold excess of K3Fe(CN)6 fully converts 1 mM Pu(VI) to the heptavalent state within 4 min (rate constant 1.3 l mol−1 s−1 at 20°C). With an increase in the NaOH concentration, the oxidation rate increases, and smaller excess of K3Fe(CN)6 is required. This oxidant is consumed not only for Pu(VI) oxidation but also in reactions with H2O and OH− ions. Pu(VII) is unstable and is slowly reduced with water and with products of decomposition of iron complexes. 相似文献
6.
Tomohito Kameda Toshiaki Yoshioka Fumiko Yabuuchi Miho Uchida Akitsugu Okuwaki 《Bulletin of Materials Science》2008,31(4):625-629
In this study, we confirmed that the characteristics of anion intercalation into the interlayer of a hydrotalcite-like compound
(HT) during synthesis are similar to those of the anion-exchange reaction of HTs as well as the reconstruction reaction of
HTs from Mg-Al oxide. We demonstrated that (i) Cl−, which has a higher charge density than NO3−, more easily reacted with Mg and Al species to form HT structure, resulting in greater intercalation of Cl− into the HT interlayer; and (ii) for HTs with lower Mg: Al molar ratios, OH−, which has a higher charge density than Cl− and NO3−, was more likely to interact with Mg and Al species to form HT structure, blocking the intercalation of Cl− and NO3−. Furthermore, we showed that high concentrations of Cl− and NO3− in solution regulated their intercalation into the HT interlayer. The high activity of Cl− and NO3− in solution would facilitate the anions’ reactions with Mg and Al species to form HTs, resulting in a high degree of anion
intercalation into the interlayer of HTs. 相似文献
7.
The total stability constants of Th4+, U4+, Np4+, Pu4+, Am4+, Cm4+, Ce4+, Tb4+, Pr4+, Tb3+, and Pr3+ complexes with P2W17O 61 10? heteropolyanion in 1 M sodium salt solutions at pH ≥ 5.5 (i.e., when the anion is not protonated; so-called “absolute” constants), were determined experimentally or calculated from published data. Plots of constants vs. ionic radius of the f element were considered for solutions with ionic strength 1 (1 M acid or sodium salt solutions at pH ≥ 5.5). The correlations found confirm that the interaction of counterions in the complex is predominantly electrostatic. At the same time, different contributions of the covalent interaction for actinides and lanthanides were suggested. 相似文献
8.
Yu. O. Lekina I. S. Glazkova A. A. Belik I. A. Presniakov A. V. Sobolev 《Inorganic Materials》2018,54(10):990-997
This paper presents results of a 57Fe probe Mössbauer spectroscopy study of the BiNi0.9657Fe0.04O3 nickelate. The spectra measured above its TN demonstrate that Fe3+ cations heterovalently substitute for Ni2+ nickel (←Fe3+), being stabilized on four sites of the nickel sublattice in the structure of BiNiO3. Calculations in an ionic model with allowance for monopole and dipole contributions to the electric field gradient indicate that the parameters of electric hyperfine interactions between 57Fe probe atom nuclei reflect the specifics of the local environment of the nickel in the structure of the unsubstituted BiNiO3 nickelate. Below TN, Mössbauer spectra transform into a complex Zeeman structure, which is analyzed in terms of first-order perturbation theory with allowance for electric quadrupole interactions as a small perturbation of the Zeeman levels of the 57Fe hyperfine structure, as well as for specific features of the magnetic ordering of the Ni2+ cations in the nickelate studied. 相似文献
9.
Cyril Koughia Gokulakrishnan Soundararajan Safa Kasap Trevor Allen Chris Haugen Ray Decorby N. Ohrui Takeshi Aoki C. Fujihashi 《Journal of Materials Science: Materials in Electronics》2009,20(1):19-22
The positions of Stark levels have been determined, using a step-by-step procedure, in the 4I9/2 and 4F3/2 manifolds of Nd3+ ions from absorption and photoluminescence measurements in the 12–293 K temperature range. This data has been used to calculate the emission cross-section for which the maximum value turns out to be ~2.3 × 10?20 cm2. The radiative recombination time, calculated using Judd–Ofelt analysis, of the 4F3/2 manifold is in close vicinity to the experimentally determined times that were measured by the conventional decay of PL after interruption of excitation and by QFRS. Moreover, the peak time defined by QFRS is independent of temperature. Therefore, the dominant relaxation mechanism from the 4F3/2 excited manifold of Nd3+ ions in GaLaS glass is believed to be by radiative emission. 相似文献
10.
Shumian Xu Sha-sha Liu Cong Zhao Tao Han Dachuan Zhu 《Journal of Materials Science: Materials in Electronics》2017,28(14):10061-10066
The Ba2P2O7:Tb3+, R (R?=?Eu2+, Ce3+) phosphors were synthesized by use of a co-precipitation method. Crystal phase, excitation and emission spectra of sample phosphors are analyzed by means of XRD and FL, respectively. The emission spectra of Ba2P2O7:Ce3+, Tb3+ phosphors exhibit four linear peaks attributed to the 5D4?→?7FJ (J?=?6–3) transition of Tb3+ while four broad emission bands are observed in the emission spectra of Ba2P2O7:Eu2+, Tb3+ phosphors. The effects of Eu2+ concentration on the luminescent properties of Ba2P2O7:Tb3+, R (R?=?Eu2+, Ce3+) are studied. Ce3+ affects the luminescent properties of Ba2P2O7:Ce3+, Tb3+ phosphors just as the sensitizer. However, Eu2+ is considered both as the sensitizer and the activator in Ba2P2O7:Eu2+, Tb3+ phosphors. The chromaticity coordinates of Eu2+ and Tb3+ co-doped phosphors gather around the white light field with the CCT approximate to 5000 K, indicating that the luminescent property of Ba2P2O7:Eu2+, Tb3+ phosphors may approach to a desired level needed for white LED application. 相似文献
11.
Yan Wang Jinghong Ma Dong Liang Meimei Zhou Fuxiang Li Ruifeng Li 《Journal of Materials Science》2009,44(24):6736-6740
Super-acid catalyst, SO4 2?/ZrO2–SiO2, with high zirconium loading was synthesized and the nature of the surface acid was investigated by FT-IR of pyridine adsorption. With the increasing ZrO2 content, the Lewis and Brønsted acid sites increased and reached the maximum when Zr/Si (molar ratio) = 1.3. The sample with Zr/Si = 1.3 showed the strongest IR adsorption band in the S=O stretching region (1,300–1,400 cm?1). Pyrosulfate and monosulfate species existed on the surface of the catalysts and the acidic strength could be enhanced by induction effect of their S=O groups. And there were two kinds of Brønsted acid sites on the surface of the catalysts. 相似文献
12.
Qiguo Sheng Haiping Xia Qingyang Tang Shinan He Baojiu Chen 《Journal of Materials Science: Materials in Electronics》2018,29(10):7987-7992
This paper reported on optical spectra of Na5Lu9F32 single crystals co-doped with ~?0.91 mol% Ho3+ and various Yb3+ concentrations by using an improved Bridgman method. The emission spectra and fluorescence decay curves were measured to investigate the luminescent properties of the Ho3+/Yb3+ co-doped Na5Lu9F32 and the energy transfer process from Yb3+ to Ho3+ ion. Compared with the Ho3+ singly doped Na5Lu9F32 crystal, the Ho3+/Yb3+ co-doped crystal had an obviously enhanced emission at 2.0 µm via the 980 nm laser diode excitation because of the efficient energy transfer from Yb3+ to Ho3+ ion. The maximum emission intensity at 2.0 µm was obtained at about 6.99 mol% Yb3+ concentration when the concentration of Ho3+ ions is fixed at ~?0.91 mol% in the current research. The maximum emission cross section of the above sample at 2.0 µm was calculated to be 1.23?×?10?20 cm2 according to the measured emission spectrum. The energy transfer efficiency from Yb3+:2F5/2 to Ho3+:5I6 for the crystal was estimated up to 90.8% indicating that Yb3+ ions can efficiently sensitize the Ho3+ ions. 相似文献
13.
Glasses of the 0.5Er3+/2.5Yb3+ co-doped (40Bi2O3–20GeO2–(30 − x)PbO–xZnO–10Na2O system where x = 0.0, 5, 10, 15, 20, 25, and 30 mol%) have been characterized by FT-IR spectroscopy measurements to obtain information about
the influence of ZnO-substituted PbO on the local structure of the glass matrix. The density and the molar volume have been
determined. The influences of the ZnO-substituted PbO on the structure of glasses have been discussed. The dc conductivity
measured in the temperature range 475–700 K obeys Arrhenius law. The conductivity decreases while the activation energy for
conduction increases with increase ZnO content. The optical transmittance and reflectance spectrum of the glasses have been
recorded in the wavelength range 400–1100 nm. The values of the optical band gap E
opt for all types of electronic transitions and refractive index have been determined and discussed. The real and imaginary parts
ε1 and ε2 of dielectric constant have been determined. 相似文献
14.
The potential of the Fe(CN)63−/Fe(CN)64− couple in solutions containing 0.5–1 M alkali and high concentrations of Li, Na, and K salts was estimated potentiometrically.
The reactions of Fe(CN)63− with Np(VI) in such media were studied by spectrophotometry. In 0.5–1 M KOH + 7 M KF or 0.5–1 M KOH + 8 solutions, Np(VI)
is oxidized to the heptavalent state with a small excess of Fe(CN)63−. In the presence of lithium or sodium salts, a larger excess of the oxidant is required for complete oxidation of Np(VI).
Carbonate ions in concentrations exceeding 2 M prevent the Np(VI) oxidation. 相似文献
15.
Sonam Rani Sujata Sanghi Ashish Agarwal Neetu Ahlawat 《Journal of Materials Science》2009,44(21):5781-5787
Lithium ion transport has been studied in bismuth lithium phosphate glasses in the frequency range 20 Hz–1 MHz and in the
temperature range 423–573 K using impedance spectroscopy. The addition of Bi2O3 in Li2O·P2O5 glass is related to the modification of the glass structure and facilitates the Li+ ions migration. The ac and dc conductivities, activation energy of the dc conductivity and relaxation frequency are extracted
from the impedance spectra. Conductivity of the present glass system is found to be ionic in nature. The electrical response
of the glasses has been studied using both conductivity and electric modulus formalisms. A single ‘master curve’ for normalized
plots of all the modulus isotherms observed for a given composition indicates the temperature independence of the dynamic
processes for ions in these glasses. Nearly identical values of activation energy for dc conduction and for conductivity relaxation
time indicate that the ions overcome same energy barrier while conducting and relaxing. 相似文献
16.
G. H. Mhlongo O. M. Ntwaeaborwa M. S. Dhlamini H. C. Swart K. T. Hillie 《Journal of Materials Science》2010,45(19):5228-5236
The successful incorporation of ZnO nanoparticles in Pr3+-doped SiO2 using a sol–gel process is reported. SiO2:Pr3+ gels, with or without ZnO nanoparticles, were dried at room temperature and annealed at 600 °C. On the basis of the X-ray
Diffraction (XRD) results, the SiO2 was amorphous regardless of the incorporation of Pr3+ and nanocrystalline ZnO or annealing at 600 °C. The particles were mostly spherical and agglomerated as confirmed by Field
Emission Scanning Electron Microscopy. Thermogravimetric analysis of dried gels performed in an N2 atmosphere indicated that stable phases were formed at ≥900 °C. Absorption bands ascribed to 3H4-3P(J = 0,1,2), 1I6 and 1D2 in the UV–VIS region were observed from SiO2:Pr3+ colloids. The red cathodoluminescent (CL) emission corresponding to the 3P0 → 3H6 transition of Pr3+ was observed at 614 nm from dried and annealed SiO2:Pr3+ powder samples. This emission was increased considerably when ZnO nanoparticles were incorporated. The CL intensity was measured
at an accelerating voltage of 1-5 keV and a fixed beam current of 8.5 μA. The effects of accelerating voltage on the CL intensity
and the CL degradation of SiO2:Pr3+ and ZnO·SiO2:Pr3+ were also investigated using Auger electron spectroscopy coupled with an Ocean Optics S2000 spectrometer. 相似文献
17.
A. N. Georgobiani V. B. Gutan M. A. Kazaryan A. V. Krotov O. Ya. Manashirov Yu. P. Timofeev 《Inorganic Materials》2009,45(10):1166-1170
Ce3+ doping of Y2O2S:Er3+ can be used to suppress the visible anti-Stokes luminescence of the phosphor under excitation in the range 0.90–0.98 μm.
We take advantage of this effect to create a new, efficient “invisible” IR phosphor emitting in the range 1.5–1.6 μm. 相似文献
18.
E. N. Galashov V. V. Atuchin T. A. Gavrilova I. V. Korolkov Y. M. Mandrik A. P. Yelisseyev Zhiguo Xia 《Journal of Materials Science》2017,52(22):13033-13039
Garnet phosphor Y3Al5O12:Ce3+ is prepared in the Y2O3–Al metal–CeO2 ternary system by the solid-state reaction method in the air. For the first time, metal Al is used as a source of aluminum for the reaction instead of traditional oxide Al2O3. It is shown that the chemical reaction can be realized at lower temperatures and without use of special reducing atmosphere. The structural and spectroscopic properties of the prepared powder phosphor are very close to those earlier reported for the Y3Al5O12:Ce3+ single crystal. 相似文献
19.
A specific feature of U(IV) oxidation with xenon difluoride in aqueous H2SO4 solutions is low-temperature chemiluminescence (CL), which in the course of warming the sample quickly cooled to 77 K is recorded starting from 165 K and reaches a maximum at about 200 K. Exothermic phase transitions, crystallization of the ice + H2SO4·4H2O and ice + H2SO4·6.5H2O eutectics, occur in the same temperature range. The data (temperature dependences of the chemiluminescence intensity and simultaneously recorded DTA curves) obtained in experiments with variation of the rate of mixing and cooling the solutions and of the concentrations of H2SO4 and F? and UO 2 2+ ions are well explicable by the catalytic activity of the juvenile surface of H2SO4 crystal hydrates toward low-temperature reaction of U(IV) with XeF2. 相似文献
20.
O. V. Nipruk N. G. Chernorukov K. A. Chaplieva G. N. Chernorukov 《Inorganic Materials》2016,52(5):504-509
We have developed a process for the synthesis of Ni(II) and Zn(II) triuranates with the general formula MIIU3O10 · 6H2O through reaction of schoepite, UO3 · 2.25H2O, with aqueous solutions of nickel and zinc nitrates under hydrothermal conditions. Using chemical analysis, X-ray diffraction, IR spectroscopy, and thermal analysis, we have determined the composition and structure of the triuranates and investigated their dehydration and thermal decomposition. 相似文献