Melting as a dislocation-mediated phase transition

We present a theory of the melting of elements as a dislocation-mediated ph ase transition. We model dislocations near the melt as noninteracting close d loops on a lattice. In this framework we derive simple expressions for th e melting temperature and latent heat of fusion that depend on the dislocat ion density at melt. We use experimental data for more than half the elemen ts in the periodic table to determine the dislocation density from both rel ations. Melting temperatures yield a dislocation density of (0.61+/-0.20)b( -2), in good agreement with the density obtained from latent heats, (0.66+/ -0.11)b(-2), where b is the length of the smallest perfect-dislocation Burg ers vector. Melting corresponds to the situation where, on average, half of the atoms are within a dislocation core.