ION-BEAM-INDUCED AMORPHIZATION IN MGO-AL2O3-SIO2 - I - EXPERIMENTAL AND THEORETICAL BASIS

Ion beam-induced, crystalline-to-amorphous transition was studied for crystalline MgO (periclase), alpha-Al2O3, (corundum), SiO2 (quartz), M gSiO3 (enstatite), Al2SiO5 (sillimanite, andalusite, kyanite), 3Al(2)O (3). 2SiO(2) (mullite), Mg3Al2Si3O12 (pyrope), and Mg(2)A(4)Si(5)O(18) (cordierite). Samples were irradiated with 1.5 MeV Xe+ at temperature s from 15 to 1023 K, and the dose required for amorphization was deter mined by in situ transmission electron microscopy. Results suggest a p arallel between the susceptibility to ion beam irradiation-induced amo rphization and the ease of glass formation. The critical amorphization doses of ion irradiation for the crystalline phases are related to th e viscosities of melts of equivalent compositions through the activati on energies of both processes. Doses required for amorphization have a negative correlation with viscosities at melting temperatures. (C) 19 98 Elsevier Science B.V. All rights reserved.