The Diffusional Properties of Oxygen in Niobium Pentoxide Crystals and Scales Formed on Niobium

Single crystals of were grown by the Verneuil technique and machined into cylinders. Measurements of electrical conductivity of these specimens as a function of temperature and oxygen pressure were made and compared with similar work by previous investigators. By following the resistance change as a function of time on changing the environmental pressure, determinations of the diffusion coefficient of oxygen were made at varying degrees of nonstoichiometry. Oxygen diffusion coefficients were several hundredfold lower in oxide of large nonstoichiometry. Similar work was performed on scales stripped from niobium specimens after oxidation. Although absolute measurements could not be undertaken on these extensively cracked specimens, showed similar properties to . The relationship is considered of these conclusions to be oxidation behavior of niobium.