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Title: Electron microscope studies of colloidal metal oxides
Author: Gildawie, Anne M.
ISNI:       0000 0001 3498 7825
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1977
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The Electron Microscope was used to study metal salt hydrolyses and a survey of several systems was carried out. The iron and vanadium systems were chosen for more detailed examination. The self hydrolysis of 0.01M VOSO4 solution at various temperatures produced Bariandite and the stages in the hydrolysis were studied using the electron microscope. It is suggested that the final long 'needle' shaped crystals were formed by the rolling up of a thin film precursor. The self hydrolysis of Fe(NO3)3, Fe(2SO4)3 and Fe(ClO4)3 solutions at various temperatures gave alpha-FeOOH or alpha-Fe2O3 depending upon the temperature of the hydrolysis, while FeCl3 gave beta-FeOOH. The anion not only affected the structure of the product but also the morphology; sulphate and chloride anions caused the oxide hydroxide precipitates to have a pod-like morphology, and this is explained in terms of a rolling up of the thin film precursors. An overall mechanism is proposed for the precipitation of the iron oxide hydroxides and vanadium oxide in terms of a two-dimensional film which is formed by condensation of polynuclear species, and which then thickens in various ways (depending on the anion) to give the final crystalline product. This mechanism was formulated from the electron microscope evidence but is corroborated by ultracentrifuge studies in the iron system where stages corresponding to the thin films and the final product are also observed. Of the other systems surveyed it seems probable that the oxide of Al and the hydroxides of Pr, Nd and Sm are also formed by this type of mechanism.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available