Lattice instability approach to the problem of high-pressure solid-state amorphization

Abstract

We consider solid-state amorphization during compression and decompression. A short review of the experiments and the theoretical models of this phenomenon shows the main drawbacks of former concepts. The advantages of the lattice instability approach were combined with the classical theory of nucleation and growth. In our concept the disordering of the crystalline phase is assumed to be connected with activationless nucleation of critical and subcritical nuclei near the “mechanical” lattice instability threshold. The reasons for lattice instability on heating, expansion, decompression and compression are considered. We show using simple “mechanical” models of the lattice that crystals with open-packed structures should become unstable at compression and we estimate the pressure of lattice instability for some substances with the diamond-like structure. The lattice instability approach gives the explanation of most features of the amorphization phenomenon.