Radiation compaction of porous Vycor glass

A large fraction of the volume of Vycor glass consists of pores with diameters of about 4 nm. Irradiation of this porous material with 340-MeV-Xe ions at normal beam incidence at room temperature induces a gradual shrinkage of the ports until they disappear completely between 1 and 2 x 10(14) Xe/cm(2). About 10 ion impacts per pore induce about 90% volume reduction. When compaction is complete off-normal irradiation induces a lateral shift of the bombarded surface which increases linearly with ion fluence. Pore shrinkage and lateral shift are interpreted quantitatively as manifestations of pressure rt laxation and shear stress relaxation, respectively, in the hot and fluid ion track. (C) 2000 Elsevier Science B.V. All rights reserved.