  A systematic review of main physical effects generated by ion exchange in
silicate glasses is presented. Ion concentration distributions, residual stress
profiles, and refractive index effects are discussed with particular attention
on the physical and mathematical underpinnings of the ion exchange process. The
study has the purpose of presenting a scientific foundation to enable future
developments in the field. In this respect, the objective of this article is
more educational than to present new research results. Appendixes are included
to consider the detail of some specific topics without disrupting the
continuity of the overall discussion. Despite the review approach of this
study, some original topics are included, such as the concentration
distribution with variable boundary conditions and residual stress profile with
anomalies due to different relaxation mechanisms, viz., either isochoric and
non-isochoric and stress driven or free energy driven. The time scale of the
different relaxation mechanisms results, for some specific glass chemical
compositions, in the appearance of a subsurface compression maximum
progressively moving apart from glass surface and eventually turning in a
reversal from compression into tensile state upon prolonged ion exchange
processes. Finally, a broad discussion on optical effects induced by ion
exchange is presented, paying particular attention to the possibility of
experimental determination of residual stress profile.
