Lithium neutron diffraction

X-ray and neutron diffraction methods and EXAFS spectroscopy are very useful in getting structural information of solvated ions. These methods, combined with molecular dynamics and Monte Carlo simulations, have been used extensively to study the structures of hydrated ions in water. Detailed results can be found in the review by Ohtaki and Radnai [17]. The structural study of solvated ions in lion-aqueous solvents has not been as extensive, partly because the low solubility of electrolytes in 11011-aqueous solvents limits the use of X-ray and neutron diffraction methods that need electrolyte of -1 M. However, this situation has been improved by EXAFS (applicable at -0.1 M), at least for ions of the elements with large atomic numbers, and the amount of data on ion-coordinating atom distances and solvation numbers for ions in non-aqueous solvents are growing [15 a, 18]. For example, according to the X-ray diffraction method, the lithium ion in for-mamide (FA) has, on average, 5.4 FA molecules as nearest neighbors with an... 

In aqueous solutions of low concentration, when theories of ionic conductivities are applicable, no ion pairs will be formed in the case of the lithium and sodium halides at room temperature. Even in 13.9 mol (kg H20)"1 LiCl aqueous solution where the molar ratio of LiCl to H20 is 1 4, essentially no ion pairs between Li+ and Cl- ions are formed around 25°C, according to an MD simulation (28). Formation of the 1 1 ion pair between Li+ and Cl in aqueous solution is, however, concluded in 18.5 mol (kg H20) 1 aqueous solution where the nLiCI h2o molar ratio is 1 3, which is close to the saturation concentration of LiCl in water (29). Formation of the 1 1 Li+ Cl" ion pair has been suggested by a neutron diffraction method (30), but the data derived from such measurements were not in good agreement with the simulation results. No evidence has been found for ion-pair formation between Li+ and I ions at 20 and 50°C in 2.78 and 6.05 mol (kg H20) 1 aqueous lithium iodide using the solution X-ray diffraction method (31). 

The structure of Li and K ammonia solution has been recently studied by neutron diffraction experiments [36]. The results show, for saturated lithium-ammonia solutions, that the cation is tetrahedrally solvated by ammonia molecules. On the other hand, from the data of the microscopic structure of potassium-ammonia solutions, the potassium is found to be octahedrally coordinated with ammonia molecules. The Li+ is a structure making ion and K+ is a structure breaking ion in alkali metal-ammonia solutions [37, 38]. 

The temperature dependence of the resistivity of Li WOs is shown in Figure 4. For x = 0.28, the anomalous peak was very large and occurred at about 600° K. for x = 0.34 the peak was much smaller and occurred at about 300° K. With increasing lithium concentration, therefore, the peak diminished in size and shifted to lower temperatures. The peak was completely reproducible and x-ray diffraction patterns showed that the cubic crystal structure existed both below and above the temperature at which the peak occurred. However, preliminary thermal analysis measurements indicated some sort of phase change. Mackintosh (6) has suggested the possibility of ordering of the lithium atoms, and neutron diffraction studies of these cubic Lia.WOs crystals should be made below and above the transition temperature. 

KUppers H, Kvick A, Olovsson I (1981) Hydrogen bond studies CXLII. Neutron diffraction study of the two very short hydrogen bonds in lithium hydrogen phthalate-methanol. Acta Cryst B37 1203-1207... 

Orman H.J. and Wiseman P.J. Cobalt lithium oxide, CoLiOj structure refinement by powder neutron diffraction. Acta Crystallogr. C. 1984 40 12-14. 

Gummow R.J., Liles D.C., Thackeray M.M. and David W.I.F. A reinvestigation of the stmctures of lithium-cobalt-oxides with neutron-diffraction data. Mat. Res. Bull. 1993 28 1177-84. 

A variety of other y-type phases with high Li+ conductivity are derived from the Li3X04 phases with X = P, As, or V. The substitution mechanisms are of the type X (Si, Ge, Ti) - - Li, and lead to the creation of interstitial Li+ ions which are responsible for the high ionic conductivity. The highest conductivity at room temperature, 4 x 10 S cm , is found in the series Li3+j (Gej Vi j )04. Neutron diffraction has been nsed to locate the interstitial lithium ions, to determine their site occnpancy, and correlate the high ionic conductivity with the connectivity of the interstitial sites ... 

The determination of stacking faults, which can lead to diffraction line broadening (i.e. twinning) and peak shifts as well. Recent examples using X-rays are the examination of stacking faults in Ni(OH)2, which can be related to the electrochemical behavior of this material and neutron diffraction work by Berliner and Werner on the 9R structure of lithium below 20 K. 

The structure of LiIn(CH3)4 (56) (76) is a three-dimensional network. Each lithium atom is surrounded by a tetrahedral array of carbon atoms. The structure of LiB(CH3)4 (57) (79) consists of planar sheets of lithium atoms bridged by tetramethylboron groups. A unique feature is the presence of both linear and bent Li—C—B units. A neutron diffraction study of LiB(CH3)4 (79) illustrates the Li—H—C interactions present in... 

Kiippers, H., Takusagawa, T., and Koetzle, T. E, Neutron diffraction study of lithium hydrogen phthalate monohydrate A material with two very short intramolecular O H O hydrogen bonds, J. Chem. Phys. 82, 5636-5647 (1985). 

The structural information at an atomic level is essential for understanding the various properties of supercooled and glassy solutions. X-ray and neutron diffraction enables us to obtain direct structure information (bond distance and coordination number) of ionic solutions in terms of the radial distribution function. In the case of aqueous lithium halide solutions. X-ray diffraction data are dominated by halide-oxygen, halide-oxygen, and oxygen-oxygen interactions. On the contrary, neutron isotopic substitution... 

In the present study, we have made X-ray diffraction, neutron diffraction with isotopic substitution, and quasi-elastic neutron scattering measurements on highly concentrated aqueous solutions of lithium halides in a wide temperature range from room temperature to below glass transition temperature, from which the microscopic behaviors of the static structure and dynamic properties of the solutions are revealed with lowering temperature. The results obtained are discussed in connection with ice nucleation, anisotropic motion of water, crystallization, and the partial recovery of hydrogen bonds. 

The ability of neutron diffraction to probe the location of light atoms in the presence of heavier ones is particularly important in the study of lithium batteries, where the synthesis of new cathode materials in an important aspect of the development of high power density, lightweight cells for laptop... 

Lithium also forms an imide, Li2(NH) as well as a beige nitride-hydride. Li4NH [39], It was assumed that the nitride- hydride formed with an antifluorite superstructure in a large tetragonal cell however, our neutron diffraction studies [40] have not confirmed this behavior. It is formed from the nitride and hydride directly at 500 C or the decomposition of the amide under vacuum. The imide also forms from decomposition of the amide and has the antifluorite structure [41] with a rotationally disordered NH2 group. 

The structure of LiaAIDe as seen by X-ray diffraction and neutron diffraction. The size of the spheres illustrates the contribution from the different elements to the scattering. With X-rays, scattering from lithium and deuterium is nearly invisible, and X-ray diffraction gives only the position of the aluminium atoms. With neutrons, the strongest scattering is from deuterium, with both aluminium and in particular lithium weaker. This illustrates clearly the importance of combined X-ray and neutron diffraction experiments. 

The first substantial evidence for hydrogen inclusion in lithium nitride itself came at the end of the 1970s from both diffraction and spectroscopy. X-Ray diffraction (XRD) demonstrated that the lithium position within the [Li2N] planes is underoccupied by 1-2 %. [19, 20] and similar levels of lithium vacancies were confirmed later by powder neutron diffraction (PND)... 

Skipper NT, Smalley MV, Williams GD, Soper AK, Thompson CH (1995) Direct measurement of the electric double-layer structure in hydrated lithium vermiculite clays by neutron diffraction. J Phys Chem 99 14201-14204... 

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