Qiu, Jing; (1994) The influence of formation conditions on the properties of lithium titanate. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Lithium titanate (Li2TiO3) has been prepared by heating the mixture of lithium carbonate powder and titanium dioxide powder at molar ratio 1:1 at four different formation temperatures (680, 720, 820 and 920°C) for 24 hours. The samples produced were evaluated and characterized by determining the density, loss of weight on heating, particle size and surface area, etc., and by employing IR spectroscopy, X-ray diffraction, dielectric spectroscopy and solid NMR. In addition, the in-vitro release of lithium and the release mechanism of powders produced have been studied. The formation temperatures were found to affect the crystal growth on the surface of lithium titanate particles and to give three different slow release profiles of lithium in vitro (slow, intermediate and fast). An increase in the temperatures resulted in a great decrease in the release rate of lithium, especially for the first hour. No differences were found in density, loss of weight on heating and particle size of the samples made at 720°C or higher. The chemical reaction at 680°C was incomplete. The surface areas of these powders differed greatly. Factors such as heating time, particle size of lithium carbonate and the quantity of the mixture were also investigated. These factors were found to affect mainly the in-vitro release of lithium from the powder, but did not affect the properties of the powder, since the factors influenced primarily the crystallization of lithium titanate. Different tablet formulations were prepared by wet granulation, using different binders and channelling agents. The in-vitro release of lithium and the effects of the tablet weight and size were studied. A zero order of release was obtained from erodible/non-disintegrating tablets and a first order release from disintegrating tablets. The release rates of lithium from the tablets produced, however, did not exceed the release rate of lithium titanate powder. From the study of the properties of the lithium titanate samples, general and additional specifications were proposed.

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