The crystal structures of new forms of silicon and germanium

Abstract

The structures of new dense forms of silicon and germanium, recovered from high pressure experiments, have been determined from their Debye-Scherrer patterns. :For silicon, the space group is Ia3 (T~), a = 6.636 _+ 0.005 A, Z = 16, and there is one structural parameter corresponding to occupancy of 16(c) positions, with x = 0.1003 _+ 0"0008. The measured and calculated density is 2.55 g.cm -s.