Relationship between ζ-potential and dislocation mobility

A study has been made of the environment sensitivity of edge and screw dislocation motion around hardness impressions on (100) surfaces of monocrystels of MgO immersed in buffered aqueous Nad, and of LiF immersed in water, toluene and dimethyl formamide. It is shown that for MgO edge and screw dislocation mobilities are least, and hardness greatest, when ζ ≈ 0, thus providing a further example of the correlation between ζ-potential and hardness established in recent studies of a variety of inorganic non-metals, both crystalline and non-crystalline. This study shows specifically, however, that the 'ζ-correlation' extends also to dislocation mobility. For LiF, it is established that both near-surface edge and screw dislocation mobilities are environment-sensitive, thus resolving a controversy in the literature on this point.