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

Abstract

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.

Real-Time Examination of Atomistic Mechanisms during Shock-Induced Structural Transformation in Silicon

“…For example, it has been suggested that the β-Sn structure can be obtained through continuous deformation with a large compression along a <100> cd direction and with isotropic expansion in the orthogonal plane [31][32][33][34]. Assuming this transformation pathway from the cd to β-Sn structure along with the commonly accepted transformation pathway from the β-Sn to sh structure [12,14,15,18,30,33], results in orientation relations between the cd and sh phases that are not compatible with our experimental findings. Because of the new results, past assumptions regarding atomic transformation pathways and orientation relations for structural changes in silicon need to be reexamined.…”

“…To our knowledge, the atomic transformation mechanism and orientation relations between different polymorphs of silicon have neither been predicted directly by theory nor have they been determined previously from experiments. Instead, transformation mechanisms/orientation relations for structural changes in silicon have often been implicitly assumed [12,14,15,18,[30][31][32][33][34][35]. For example, it has been suggested that the β-Sn structure can be obtained through continuous deformation with a large compression along a <100> cd direction and with isotropic expansion in the orthogonal plane [31][32][33][34].…”

“…Instead, transformation mechanisms/orientation relations for structural changes in silicon have often been implicitly assumed [12,14,15,18,[30][31][32][33][34][35]. For example, it has been suggested that the β-Sn structure can be obtained through continuous deformation with a large compression along a <100> cd direction and with isotropic expansion in the orthogonal plane [31][32][33][34]. Assuming this transformation pathway from the cd to β-Sn structure along with the commonly accepted transformation pathway from the β-Sn to sh structure [12,14,15,18,30,33], results in orientation relations between the cd and sh phases that are not compatible with our experimental findings.…”

“…Recent molecular dynamics (MD) simulations for germanium [36] and silicon [2,23,37] shocked along [100] cd have suggested that the transformation mechanisms for structural changes between the cd silicon and the β-Sn, Imma and sh structures are more complex than commonly assumed [12,14,15,18,[30][31][32][33][34][35]. An interesting finding of the MD simulations was that the transformations occurred along shear bands [2,36,37] which were attributed to planar stacking faults [36,37].…”

Electronic properties and phase transitions in Si, ZnSe, and GaAs under pressure cycling up to 20–30 GPa in a high‐pressure cell

“…This means that the effects of applied pressure on the electronic and atomic subsystems of Si do not coincide, and consequently they can result in different P t . Both the possibilities evidence the complicated nature of the S-M transition in Si [21,22].…”