Electronic theory for impurity segregation at lattice defects in metals

A tight-binding type electronic theory is used to study the impurity segregation at lattice defects in metals. It is shown that the heat of segregation E_segr results from a simple physical origin: It is roughly proportional to the difference in the diagonal matrix elements (V_i-V₀) of impurity potentials, where V_i (V₀) is determined for atomic sites in the vicinity of lattice defects (for a perfect lattice site). Applications to impurity segregation at cleaved surfaces, screw dislocations and tilt grain boundaries are discussed.