Cation self-diffusion in single crystal MgO

Abstract

Measurements of the self-diffusion of Mg²⁺ in single crystal MgO of two different purities have been made over the temperature range 1100°C to 1750°C. Above approximately 1300°C the results show direct evidence of the operation of both intrinsic and extrinsic diffusion. Below this temperature precipitation of the non-active impurities present appears to take place. Using the earlier similar but apparently purely intrinisic measurements of Lindner and Parfitt (1957) it is possible to evaluate both the enthalpy of motion for the cation vacancy, H _m, and the enthalpy of formation of the complete Schottky defect, H _f. The results obtained are: H _m = 1·7±0·1 ev; H _f = 3·4±0·2 ev.