Close packing and pressure-induced amorphization

Abstract

Recently a large number of crystalline compounds have been discovered to amorphize at high pressures. However, 1 the molecular origin of this transformation is not under- ' stood. In this article, we show that this is a : consequence of a competition between the close-packing i and long range order — a principle well known in organic 1 crystallography. We show that the tendency of these i systems to acquire higher coordination under compression is ; sterically hindered at some pressure due to the strong , nature of inter-molecular bonding of building blocks.This hindrance drives the system to sacrifice the transitional order to achieve better packing. The application of principle is shown through the examples of Ca(OH)₂, SiO₂, ice, LiKSO₄, etc.