~ Symmetry Splitting of Equivalent Sites in Oxide Crystals and Related Mechanical Effects

Changes in the sy mmetry of a crystal caused by an appl ied strain have bee n uscd to show in what ci rcumstances an in tern a l friction pea k can res ult from the motion of isolated point defects. General rules are given to make the pred iction, and these are applied to several structures of common oxides. The prediction for rutile is compared with experi-mental results which are in terpre ted by the movement of t itanium io ns between interst itia l pos ition ~ in the structure. 1