An axial asymmetry about, the direction of motion of Li⁵ has been seen in the breakup of the ground state of this nucleus as an intermediate state in the reaction Li⁶(He³,pα)He⁴. The total cross section for this process was found to be a few hundred millibarns, an order of magnitude greater than predicted by a statistical model calculation, and the asymmetry amounts to a factor of 2.0 ± 0.3 in the double, differential cross section. It is shown that this asymmetry in the secondary decay of the sequential breakup process can arise from the memory retained by the intermediate state of its structure during the primary reaction, in which a neutron is transferred from Li⁶ to He³. It was found that the strength of the asymmetry is sharply dependent upon the duration of the final state interaction. This confirms the proposed interpretation and suggests that further data could lead to useful information regarding correlation of the p-shell nucleons in the Li⁶ ground state. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The reactions of lithium disks with dry and moist nitrogen and with water-vapour were investigated at temperatures from 22 to 70 degrees Centigrade with the use of a thermal balance. The reaction in nitrogen commenced with nucleation of lithium nitride at corners and edges of the sample and the reaction proceeded by lateral growth of these nuclei through the specimen. In moist gas, this reaction was accompanied by the simultaneous formation of lithium hydroxide at the plane surface of the specimen. Based on visual observations of the samples during the reaction, a model describing the geometry of nucleus formation was constructed and was used to calculate growth velocities from the reaction curves obtained with the thermal balance. The dependence of growth velocity on temperature, nitrogen partial pressure, and the moisture content of the reaction gas was investigated. The reaction with water-vapour was observed to proceed in three distinct stages. The results have been explained in terms of a model involving recrystallization and hydration of an initially coherent lithium hydroxide film. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

This thesis is concerned with the thermal decomposition of a series of alkyllithium compounds in the pure state in an attempt to determine the relative stability of alkyllithium compounds and to examine the mechanism of the elimination reaction.

No description available.

No description available.

No description available.

none

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2007. / Includes bibliographical references.

The effects of lithium alkoxides on the rates of reactions and on the structures of a series of tert-butyllithium/lithium alkoxide mixed aggregates were studied, where the alkoxides were iso-butoxide, tert-butoxide and menthoxide. It was found that their effects depend not only on their amount present, but also on their steric bulk. The tert-butyllithium/lithium alkoxide mixed aggregates were exposed to UV light or heat to form lithium hydride/lithium alkoxide mixed aggregates. The aggregation states were assigned from either 13C-6Li coupling or a new technique based on the relative intensity of NMR peaks using different nuclei. The compounds formed depend upon the method of formation and the alkoxide. The unique properties of the lithium hydride/lithium alkoxide mixed aggregates are their high solubility in hydrocarbon solutions, very reactive bases, showing 6Li-1H couplings, and having only one hydride ion per aggregate. Their formation, reactivity, solubility, and aggregation states were found to depend on the size of lithium alkoxides. X-ray crystal structures of lithium tert-butoxide and lithium menthoxide were also studied and found to be hexameric.

Lithium is one of the most strategically important minerals at the time of writing. The demand for lithium and lithium compounds to be used in lithium-ion batteries is increasing day by day. Zimbabwe possesses a considerable resource of lithium ore, estimated at 23 000 mt Li. Beneficiation of this lithium ore could indeed be a very promising business in the near future. This work focuses on processing of petalite concentrate from the Bikita deposit in Zimbabwe for production of Li2CO3, with subsequent preparation of LiF and LiCl. Analysis performed on the petalite showed that the average Li2O content is 4.10 %. The extraction method used involves roasting the pre-heated concentrate with concentrated H2SO4 followed by water leaching of the resulting Li2SO4, solution purification and precipitation of Li2CO3 with subsequent preparation of LiF and LiCl. Investigation of the roasting and leaching showed that the dissolution rates are significantly influenced by roasting temperature and stirring speed. 97.3 % optimum rate of extraction was attained at 320 rpm and roasting temperature of 300 C. Water-washed lithium carbonate with a purity of 99.21 %( metal basis) and an average particle size of 1.4 ìm was produced. Good quality LiF and LiCl can be produced with purity of 99.36 % and 99.02 % respectively. The pH, concentration and agitation have a great influence on the morphology of the precipitated LiF. Lower pH values and optimum concentration of the Li2CO3 solution results in smaller particle size. High recovery of 96.53 % LiF was realised. Anhydrous LiCl was found to absorb moisture when exposed to air at ambient temperature. The synthesised LiCl melts at 606.2 C with a corresponding enthalpy of fusion of 18.4 kJ mol-1, close to the values reported in the literature. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Chemical Engineering / unrestricted