Diffusion of Cobalt, Nickel, and Iron in Cobalt Oxide and Nickel Oxide

摘要

Self diffusion and impurity diffusion measurements of Co60, Ni63, and Fe55 radiotracers were made in single crystals of nickel oxide and cobalt oxide. The measurements were made by the technique of sectioning the crystals and determining the residual activity remaining in the sample. The diffusion coefficients were measured between 1100C and 1400C in oxygen partial pressures from one to 0.00005 atmospheres. An exact solution for the diffusion equation in the section-and-count experimental technique was derived and a computer program was prepared to plot the solution. Data analysis was accomplished by comparison of experimental profiles to those generated by the computer. A defect model based on total cation vacancy content of the host crystal was proposed to explain the variations of the diffusion coefficients with temperature, oxygen partial pressure and dopant concentrations. (Author)