Theory of the high-pressure structural phase transitions in Si, Ge, Sn, and Pb

Displacive mechanisms are proposed for the high-pressure structural transitions which take place in Si, Ge, Sn, and Pb. The mechanisms are analyzed in the framework of the Landau theory of phase transitions. It reveals a number of unifying features which are discussed in connection with the electronic structures of these elements, leading to a more precise understanding of the diversity of phase diagrams found for the elements of Group IVa.