Self‐Diffusion of 60Co in Co1‐xO Single Crystals of Controlled Stoichiometry

Abstract

Cobalt tracer self‐diffusion coefficients were determined in single crystals of Co1‐x O at 1037° to 1350°C and for x=0.002 to 0.00s. In crystals with x fixed at 0.005, the results wereThe activation energy in this constant‐stoichiometry case was identified as the enthalpy of motion for Co ions moving via a vacancy jump mechanism. Based on known stoichiometry rela‐ tions, a published activation energy for Co self‐diffusion mea‐ surements in air was corrected to yield an enthalpy of motion in excellent agreement with the number given above. At a constant temperature of 115O0°±2°C, the Po2 dependence of Co self‐ diffusion wasThe Po2 expynent suggests that the predominant mobile ion defects are singly ionized Co vacancies. Simple defect reactions with no modifications for defect clustering were adequate to explain all results obtained.