Glass hardness modification by means of ion implantation: Electronic doping versus surface composition effect

Abstract

Critical load measurements point to an improvement in the hardness of a soda–lime glass upon nitrogen implantation. In order to determine whether this improvement originates from electronic doping or surface composition changes induced by ion implantation, a theoretical approach using quantum-chemical and force-field methods combined with X-ray photoelectron spectroscopy is performed. The results indicate that neither an electronic effect nor a lattice distortion appear to be the primary cause of the hardness improvement. It is rather a change in the surface composition leading to a more densely cross-linked and stiffer silica network at the top surface of the glass which is at the origin of this improvement.