The mechanism of radiation-induced compaction in vitreous silica

We describe vitreous silica as a two-phase system. Low-temperature phase A and high-temperature phase B are connected by a solid-state phase transitio n and the phase transition temperature should be higher than the glass tran sition temperature. This model is based on the observed volume change induc ed by hydrostatic pressure, fast neutron, ion, electron and photon radiatio n, etc. Compaction induced by knock-on radiation in vitreous silica is diff erent from compaction induced by ionizing radiation. For the latter, the ob served stretched power dependence of compaction on deposited energy for ion ization damage can be explained by applying a simple relaxation model. (C) 2000 Elsevier Science B.V. All rights reserved.