Evidence of screw dislocations in graphite

Abstract

Spiral etch pits are produced by etching natural graphite cleavage flakes in sodium peroxide. By etching matched cleavage faces, a correspondence has been found between the number, nature and position of the spiral etch pits on these faces. Similar correspondence has been found in the etch patterns produced on the two sides of a thin flake of graphite, 95 ?m thick, from which it is inferred that the spiral pits indicate the sites of screw dislocations on the cleavage face and that they run right through the body of the crystal.