A XANES investigation of the network-modifier cations environment before and after the Na+/K+ ion-exchange in silicate glasses

μ-XANES is used to study the modifications in the alkali and alkaline-earth environments induced by the Na+/K+ ion-exchange process in various Na –silicate glasses. The results indicate that the ion-exchange process induces a shortening of the NaO, CaO and MgO bond distances. The contraction of the NaO, CaO and MgO coordination shell allows a better accommodation of the K+ cations in the glass network and thereby leads to partial relaxation of the stress developed by the Na+/K+ ion-exchange. Nevertheless, despite the stress relaxation process, the K+ environment in the ion-exchanged glass is not equivalent to the one in Na,K–silicate as-melted glasses. Hence, this study clearly shows that the ion swapping forced K+ cations to occupy smaller sites which are not achievable via the melt quench route for glasses with the same K amount. •μ-XANES is used to study stress/structural relaxation in silicate glass upon Na+/K+ ion-exchange•The ion-exchange process induces a shortening of the Na-O, Ca-O and Mg-O bond distances•These shortenings allow a better accommodation of the K+ cations in the glass and lead to partial relaxation of the stress