共查询到20条相似文献,搜索用时 46 毫秒
1.
H. Degraix P.C. Gravelle S.J. Teichner P. Turlier 《Journal of solid state chemistry》1976,18(1):69-77
Heating mixtures of lithium and nickel oxides at 1073°K under reduced oxygen pressure (<10?6 Torr) produces the incorporation of lithium ions in the nickel-oxide lattice. The solubility appears to be limited at 1.9 at Li %. From a study of several properties of solid solutions, it is concluded that the incorporation of lithium ions creates and stabilizes anionic vacancies. 相似文献
2.
Ionic transport number measurements have been made on single crystals of NiO over the temperature range 900–1300°C and for oxygen partial pressures varying from 10?8 to 1 atm. At 1000°C and in air, tNi ~ 2 × 10?7. The variation in cationic conductivity as a function of oxygen partial pressure suggests that V′Ni is the dominant defect at high temperature and low oxygen pressure and that V″Ni is the dominant defect at low temperature and high oxygen pressure. 相似文献
3.
The measurement of the cationic transport numbers in MgO single crystals has been performed, using the dilatocoulometric method. In the oxygen partial pressure range 1 to 10?10 atm at temperatures of 1100 to 1300°C the ionic conduction in MgO is extrinsic. 相似文献
4.
Raman spectra (4000-150 cm?1) of a single crystal of NaGa(NH2)4 and infrared spectra (4000-200 cm?1 ) of a polycrystalline sample have been studied at different temperatures. An assignment of the bands is given. The spectra are discussed assuming S4 and Td point group symmetry of the Ga(NH2)?4 ion at low temperature and at room temperature respectively. Metal-ligand and N-H stretching frequencies are compared to those of some other amido metalates. 相似文献
5.
R. Rumin 《Journal of organometallic chemistry》1983,247(3):351-356
The chloro-bridged platinum(II) complex dichlorobis(2,4,6-trimethylpyridine)-platinum was found to be an active catalyst for homogeneous hydrogenation and hydrosilylation of olefins and α,β-unsaturated aldehydes and ketones at room temperature and under atmospheric pressure. Hydrosilylation of terminal olefins can be achieved with dimethylphenylsilane and a catalyst/reactant ratio of 10?6/1. This complex is the first example of a platinum(II) compound containing pyiridine ligands having good catalytic activity possibilities. 相似文献
6.
The standard enthalpies of solution of NH4F and NH4HF2 in aqueous solutions of hydrogen fluoride (in the range of concentration 0–30 mol.1?1) have been measured and from these results the standard enthalpy of formation of NH4HF2(c) has been derived as: δHofNH4HF2(c) = ?809.9 ± 0.9 kJ.mol?1 相似文献
7.
Jean Santamaria 《Tetrahedron letters》1981,22(45):4511-4514
Photo-oxygenation of aromatic compounds sensitized by electron acceptors, like 9-10 dicyanoanthracene (DCA) is shown to proceed by two distinct mechanisms each one beginning by an electron-transfer step: in the first way superoxide ion [O2?] is involved and in the second one singlet oxygen [1O2*] is produced according to an unusual process. 相似文献
8.
In a previous paper we have shown that at 740°C and under an oxygen pressure less than 1,3 torr the electrical conductance G of a NiO powder reaches rapidly an apparently stabilized signal Gi which sharply decreases after a sufficiently long time to a G0 value independent of PO2.From this observation we have studied the influence of the temperature successively on the electrical conductance Gi and G0. The Arrhenius law is only verified for the G0 = f(T) curve. G0 appears as the representative value of the gas-solid equilibrium. 相似文献
9.
Purity control of high-purity nickel by direct γ-spectrometry after irradiation with thermal neutronsThe possibilities of analysing high-purity nickel samples by direct γ-spectrometry with a Ge(Li) detector after neutron activation are described. The samples (300—600 mg) are irradiated for 65 h in a thermal neutron flux of 5 X 1012 n cm-2 s-1 and the matrix radioactivity is then allowed to decay for 30 h. It is possible to determine simultaneously 18 elements (the commonest impurities in nickel) by using standards containing known quantities of these elements irradiated under the same experimental conditions. Concentration limits are calculated for 15 elements based on the nuclear characteristics of the radio-isotopes which can be detected by neutron activation. It should be possible to determine 22 elements in nickel samples, at concentrations below 0.1 μg g-1. The method is suitable for laboratories situated far from irradiation facilities. 相似文献
10.
11.
Conjugate addition of reagent 1A to 2-cyclohexenone 3 can be realized in THF-HMPT, so that one-pot conjugate addition—CH3I enolate trapping, leading to trans 2-methyl 3-benzoylcyclohexanone 17 can be easily performed. From isophorone 4 and Δ1(9)-2-octalone 5, 1, 4-addition under kinetic control is observed in THF. In the presence of HMPA, the reaction is under thermodynamic control. At low temperatures enolate 19a is in equilibrium with 1A and 4; from 4 at 0° or 5 at ?65° or at 0°, the equilibrium lies on the side of starting materials. No reaction between 1A and 6 takes place in any solvent.The reaction of 1B and isophorone 4 in THF leads to 1, 2-addition under kinetic control and to 1, 4-addition under thermodynamic control. In THF-HMPT, retro-Michael addition is observed. However, 1, 2-addition takes place in THF to 6.The different results are interpreted in terms of interplay of ion-pairing, steric decompression and steric hindrance to 1, 4-addition as well as the possibility of participation of the Li cation for 1, 2-addition. 相似文献
12.
Kinetic measurements show the relation between the magnitude of the “α effect” exhibited by trifluoromethyloximate anions RR'C=N-O? and the electron attracting properties of the substituents. Indeed, the reactivity enhancement which is observed for α-trifluoromethyloximes is similar to that found in earlier studies of α-hydroxyiminoketones. This characteristic behaviour is no longer observed for oximes bearing an electron releasing substituent at the α-position of the hydroxyimino group. On the basis of sodium oximate molecular orbital energies the “α effect” induced by electron attracting substituents appears to depend on both the interactions of nitrogen and oxygen lone pairs of electrons and the lowering of the π* vacant orbital thus favouring a secondary interaction between the π* anion orbital and the π orbital of p-nitrophenylacetate carbonyl group. 相似文献
13.
Bärbel Gosse 《Journal of Electroanalytical Chemistry》1975,61(3):265-279
Measurements of the polarization of a plane platinum electrode in nitrobenzene solutions are presented and discussed. The supporting electrolyte concentration is made to vary between 10?1M and a value lower than 10?6M; the highest resistivity value (2×108 Ω cm) of the studied solutions was imposed by the experimental procedure. Concentric spherical electrodes have also been studied. The polarization-current density curves do not vary with the electrolyte concentration or nitrobenzene resistivity. The electron-transfer mechanism is not modified in high resistive media. The influence of spacing on the polarizations of two plane parallel electrodes set very close to each other is investigated, too. The polarizations are found nearly constant and thus independent of the amount of free ions in the volume of liquid between the electrodes, even when it is theoretically too low to establish the voltage drop at the interface. The results indicate a strong interaction of the electrode reactions at such low spacings and the formation of ions from the weakly ionized impurities of nitrobenzene. 相似文献
14.
15.
The conventional absorbance-ratio technique for determining the isotopic composition of lithium by atomic absorption spectrometry is improved by the use of “ultimate absorbance ratios” of sample solutions. These ratios are obtained by extrapolating the linear portion of lithium content/absorbance-ratio plots to the intercept at 0 mol m?3 lithium. These graphs are obtained measuring the absorbances of solutions of known 6Li abundance and of various lithium contents with natural and 6Li-enriched lithium hollow-cathode lamps. Linear calibration is attained over the range 0.0–99.3% 6Li, and the lithium isotopic abundance can be determined with an absolute error of ±0.7% 6Li for > 0.01 mol m?3 lithium solutions. The method requires neither prior measurement of the total lithium content in sample solutions nor adjustment of the content to match that in the standard solutions. 相似文献
16.
Pierre Krausz Jean Guillerez Francis Garnier 《Journal of organometallic chemistry》1978,161(1):97-108
The cis-trans interconversion of olefins in the system W(CO)6 + CCl4 + 2-butene is studied, both with initial irradiation of a solution of W(CO)6 in CCl4 (photoinduction), and with continuous irradiation of the system, for cis- and trans-butene concentrations between 0.09 and 6.0 M. Analysis of the results of the photoinduction experiments (rate of conversion and kinetic law as a function of the initial concentration of the olefin) allowed us to propose a simple kinetic scheme comprising a cis-trans interconversion of 2-butene and olefin-catalyzed destruction of the catalytic entity (k2 = (0.62 ± 0.06)x10?4 M s?1). In the continuous irradiation experiments the final distribution of the olefin was independent of the initial butene concentration (cis-2-butene/trans-2-butene 3.0) and the reaction kinetics are of first-order (kobs = (3±1) x10?4 s?1. Comparison of the two experiments suggests continuous photochemical regeneration of the catalytically active entity. The first-order reaction kinetics are in agreement with a carbene-metal carbonyl structure of the intermediate 相似文献
17.
Tingting Zheng Chunyan Shang Zhihai He Xinyi Wang Cong Cao Hongliang Li Rui Si Bicai Pan Shiming Zhou Jie Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14906-14911
Developing bifunctional catalysts for both hydrogen and oxygen evolution reactions is a promising approach to the practical implementation of electrocatalytic water splitting. However, most of the reported bifunctional catalysts are only applicable to alkaline electrolyzer, although a few are effective in acidic or neutral media that appeals more to industrial applications. Here, a lithium‐intercalated iridium diselenide (Li‐IrSe2) is developed that outperformed other reported catalysts toward overall water splitting in both acidic and neutral environments. Li intercalation activated the inert pristine IrSe2 via bringing high porosities and abundant Se vacancies for efficient hydrogen and oxygen evolution reactions. When Li‐IrSe2 was assembled into two‐electrode electrolyzers for overall water splitting, the cell voltages at 10 mA cm?2 were 1.44 and 1.50 V under pH 0 and 7, respectively, being record‐low values in both conditions. 相似文献
18.
Determination of isotopic composition of lithium by neutron activation analysis; comparison with mass spectrometry 总被引:1,自引:0,他引:1
An activation analysis method is described for routine determination of6Li-abundances in various lithium compounds on the basis of the reaction sequence6Li(n,α)T and16O(t, n)18F and the measurement of18F. Irradiations of diluted equeous solutions of samples containing CrO3 as internal flux monitor were carried out at a thermal neutron flux density of ϕ≤1011 n·cm−2·sec−1. Interferences from variations in neutron self-shielding oxygen concentration and triton range do not exceed 0.5% when using
the dilution technique. The results for6Li abundances from 3.52 to 7.60% with standard deviations of 1 to 2.5% were confirmed by mass spectrometric measurements. 相似文献
19.
Fangyi Cheng Qing Zhao Xiaopeng Han Jun Chen 《Angewandte Chemie (International ed. in English)》2015,54(14):4338-4343
The ever‐increasing consumption of a huge quantity of lithium batteries, for example, Li–MnO2 cells, raises critical concern about their recycling. We demonstrate herein that decayed Li–MnO2 cells can be further utilized as rechargeable lithium–air cells with admitted oxygen. We further investigated the effects of lithiated manganese dioxide on the electrocatalytic properties of oxygen‐reduction and oxygen‐evolution reactions (ORR/OER). The catalytic activity was found to be correlated with the composition of LixMnO2 electrodes (0<x<1) generated in situ in aprotic Li–MnO2 cells owing to tuning of the Mn valence and electronic structure. In particular, modestly lithiated Li0.50MnO2 exhibited superior performance with enhanced round‐trip efficiency (ca. 76 %), high cycling ability (190 cycles), and high discharge capacity (10 823 mA h gcarbon?1). The results indicate that the use of depleted Li–MnO2 batteries can be prolonged by their application as rechargeable lithium–air batteries. 相似文献
20.
Zhixin Xu Prof. Jiulin Wang Prof. Jun Yang Xiaowei Miao Prof. Renjie Chen Ji Qian Rongrong Miao 《Angewandte Chemie (International ed. in English)》2016,55(35):10372-10375
The lithium–sulfur battery is regarded as one of the most promising candidates for lithium–metal batteries with high energy density. However, dendrite Li formation and low cycle efficiency of the Li anode as well as unstable sulfur based cathode still hinder its practical application. Herein a novel electrolyte (1 m LiODFB/EC‐DMC‐FEC) is designed not only to address the above problems of Li anode but also to match sulfur cathode perfectly, leading to extraordinary electrochemical performances. Using this electrolyte, lithium|lithium cells can cycle stably for above 2000 hours and the average Coulumbic efficiency reaches 98.8 %. Moreover, the Li–S battery delivers a reversible capacity of about 1400 mAh g?1sulfur with retention of 89 % for 1100 cycles at 1 C, and a capacity above 1100 mAh g?1sulfur at 10 C. The more advantages of this cell system are its outstanding cycle stability at 60 °C and no self‐discharge phenomena. 相似文献