Diffusion of oxygen in molten vanadium pentoxide

• Main Author: Balakrishnan, Ramachandran
• Format: Dissertation
• Language: English
• Published: University of London 1971

Self diffusion coefficients of oxygen in molten vanadium pentoxide have been measured using the capillary reservoir method with the stable isotope 0 18 as the Tracer. The non radioactive tracer necessitates incorporation in the procedure of an analytical method for the quantitative evolution of oxygen from the oxide for the mass spectrometric analyses of the isotopic contents. An apparatus has been described for each analyses, using bromine pentafluoride for quantitative fluorination of the oxide and subsequent mass analysis of the evolved oxygen. Diffusion coefficients have been measured as a function of temperature and of composition (stoichiometry) of the melt. The results are discussed in terms of the current theories of diffusion in liquid state. It is concluded that molten vanadium pentoxide does not possess 1 network 1 characteristics to any great extent in its mass transport behaviour and that anionic diffusion is unlikely to be free volume controlled but rather energy controlled. The relationship between the transport properties Viscosity and diffusion, are discussed and it is suggested that different mechanisms are operative in the two processes. Using coulometric titrations in conjunction with the solid oxide electrolyte Zr 02.yz03 and Fe0 evidence for the presence of an univariant equilibrium involving the molten pentoxide and a second condensed phase at comparatively high oxygen partial pressures have been obtained.