Effect of titanium and aluminum ion implantation on the microhardness of silica glass

The effect of ion implantation on the microhardness of silica glass was investigated. Silica glass was irradiated with 50-keV Ti+ and Al+ ions to doses from 1 x 10(16) to 3 x 10(17) cm(-2) and then annealed in air at 1070 K. Ion implantation causes an almost twofold increase (from 6.5 to 11.6 GPa) in microhardness. Heat treatment reduces microhardness of the ion-implanted silica glass, although not to the initial level. The increase in microhardness is attributed to radiation compaction associated with formation of radiation-induced defects, filling of microvoids, and oxygen loss in the implanted layer.