Search results for "Lithium"
showing 10 items of 680 documents
Up-conversion process in erbium doped lithium fluoride bulk crystal, lithium borate glass and glass ceramics
2007
In our research the up-conversion processes in Er doped bulk LiF crystal, lithium borate oxyfluoride glass and lithium borate oxyfluoride glass ceramics were studied: up- conversion and traditional photoluminescence spectra, the up-converted signal as a function of the laser power are presented. It was found that sharp luminescence bands in the visible part of the spectrum appear when the bulk crystal is subjected to IR irradiation at 980 nm by a laser diode. After the heat treatment of the glass submicron crystallites were detected by SEM technique. The presence of LiF crystalline phase in the oxyfluoride glass ceramics was proved by XRD method. The questions about the synthesis of the oxy…
Anomalous behaviour of periodic domain structure in Gd-doped LiNbO3single crystals
2007
Atomic force microscopy studies of etching patterns, stability of regular domain structure, and anomalies of electrical characteristics in the 300 - 385 K range of a series of Gddoped lithium niobate single crystals grown under equal conditions are reported.
Electronic aspects of the hydride transfer mechanism. III. Ab-initio analytical gradient studies of the cyclopropenyl-cation/LiH with 4-31G and 3-21+…
1988
Abstract Hydride transfer reaction have been studied in sections of the energy hypersurface of cyclopropenyl cation and lithium hydride at 4-31G and 3-21+G basis set levels. The diffuse component has enforced the idea of an hydride-ion as being the particle transferred in the ground electronic state. Calculations on the first triplet state suggest a transfer mechanism mediated by one-electron followed by an hydrogen atom transfer. The change of basis set does not affect structural and energetics aspects of the reacting system except for the transferred particle, where, for some molecular complexes, the electronic distribution can be described as a hydride ion cementing two electron defficie…
Optimal hydrogen storage in sodium substituted lithium fullerides
2017
Through the substitution of Li with Na in Li6C60, we synthesized a series of mixed alkali cluster intercalated fullerides, NaxLi6−xC60. These compounds share lattices of Na6C60 and Li6C60 with a cubic parameter linearly dependent on x. H2 absorption and desorption were studied by means of charge/discharge kinetic measurements and coupled calorimetric–manometric evaluation. By varying the stoichiometry, we found the best compromise among the absorption rate, temperature and amount of hydrogen for x = 0.5 and 1. Small concentrations of Na substituted to Li significantly lower the absorption temperature of Li6C60, improving the hydrogenation capacity, the kinetics, and the dehydrogenation enth…
Solving the Hydrogen and Lithium Substructure of Poly(triazine imide)/LiCl Using NMR Crystallography
2016
Poly(triazine imide) with incorporated lithium chloride has recently attracted substantial attention due to its photocatalytic activity for water splitting. However, an apparent H/Li disorder prevents the delineation of structure–property relationships, for example, with respect to band-gap tuning. Herein, we show that through a combination of one- and two-dimensional, multinuclear solid-state NMR spectroscopy, chemical modelling, automated electron diffraction tomography, and an analysis based on X-ray pair distribution functions, it is finally possible to resolve the H/Li substructure. In each cavity, one hydrogen atom is bound to a bridging nitrogen atom, while a second one protonates a …
Experimental investigation on lithium borohydride hydrolysis
2010
Abstract Lithium borohydride, one of the highest energy density chemical energy carriers, is considered as an attractive potential hydrogen storage material due to its high gravimetric hydrogen density (19.6%). Belonging to borohydride compounds, it presents a real issue to overcome aims fixed by the U.S. Department of Energy in the field of energy, and so crystallizes currently attention and effort to use this material for large scale civil and military applications. However, due to its important hygroscopicity, lithium borohydride is a hazardous material which requires specific handling conditions for industrial aspects. In order to understand much more the reaction mechanism involved bet…
Study of the hydrolysis of lithium hydride
2015
The hydrolysis of LiH at room temperature and under low water vapor pressure (PH2O < 10 hPa) is investigated by thermogravimetry and FTIR spectroscopy with low sample mass. Then, to be closer to industrial conditions, hydrolysis of LiH is studied by manometry either in closed (adjustable PH2O) or open (constant PH2O) system using larger amounts of sample and heavy water. Products of the reaction are characterized by X-ray diffraction and FTIR spectroscopy. The first set of experiments show that the mechanism of hydrolysis starts with the formation of lithium oxide Li2O. Then, when the oxide layer is sufficiently thick, the hydrolysis reaction is followed by the formation of lithium hydroxid…
Description of Hysteresis in Lithium Battery by Classical Preisach Model
2012
In this paper Preisach Model is applied to obtain a mathematical model of the hysteresis in lithium battery. Preisach Model allows to describe the hysteresis of charging and discharging cycles in a lithium battery. The identification of the model is obtained by using a neural network technique developed for magnetic systems. The model is verified on some experimental tests on commercial batteries.
Depth profiles of aggregate centers and nanodefects in LiF crystals irradiated with 34 MeV 84Kr, 56 MeV 40Ar and 12 MeV 12C ions
2018
I. Manika, J. Maniks and R. Zabels acknowledge the national project IMIS2. A. Dauletbekova, A. Akilbekov, M. Zdorovets and A. Seitbayev acknowledge the GF AP05134257of Ministry of Education and Science the Republic of Kazakhstan.
Laser spectroscopy measurement of the 2s-hyperfine splitting in lithium-like bismuth
2017
We have recently reported on the first direct measurement of the $2s$ hyperfine transition in lithium-like bismuth (209Bi80+) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. Combined with a new measurement of the $1s$ hyperfine splitting (HFS) in hydrogen-like (209Bi82+) the so-called specific difference ${\rm{\Delta }}^{\prime} E=-61.37(36)$ meV could be determined and was found to be in good agreement with its prediction from strong-field bound-state quantum electrodynamics. Here we report on additional investigations performed to estimate systematic uncertainties of these results and on details of the experimental setup. We show that the dominating uncertainty a…