A proposal for a transition mechanism from the diamond to the lonsdaleite type

A phase transition between the diamond (Fd (3) over barm) and the lonsdaleite types (P6(3)/mmc) may be described as a deformation of a homogeneous sphere packing with three contacts per sphere (type 3/10/o1) in the common subgroup Pnna of Fd (3) over barm and P6(3)/mmc. The frequently observed transition between the zinc-blende (F (4) over bar 3m) and the wurtzite types (P6(3)/mc) may be described in an analogous way as a deformation of a heterogeneous sphere packing in the subgroup Pna2(1). The proposed model guarantees the three-dimensional connection during the whole transformation process. By this property it is distinguished from other models.