Pressure-Induced Amorphization

Pressure-induced amorphization has been examined using a variety of experimental techniques. It has been observed that a large number of crystals will undergo pressure -induced amorphization. Covalently bonded crystals as well as molecular crystals have been found to transform to glasses upon the application of sufficient pressure. Ca(OH) _2, a crystal with weak hydrogen bonds, has been shown to be the first octahedrally coordinated crystal to undergo pressure-induced amorphization. AlPO _4 and GeI_4 are both found to undergo an increase in coordination at the amorphization pressure. For both materials, the high pressure crystalline equilibrium phase cannot be accessed due to limited atomic diffusion. Thus with the application of pressure these materials amorphize. The amorphous structure produced through pressure-induced amorphization is found to be topologically similar to the starting material. This has been shown most clearly for the case of pressure-amorphized Fe _2SiO_4, which like its crystalline counterpart, displays antiferromagnetism.