Structure and crystallization behavior of mixed potassium-lithium niobiosilicate glasses

Potassium-lithium niobiosilicate (KLiNS) glasses with a composition of (27 − x)K2O · xLi2O · 27Nb2O5 · 46SiO2 (x = 0, 3, 12 and 20) have been synthesized by a melt-quenching method. The glass structure and devitrification behavior have been studied by Raman spectroscopy, DTA, and XRD. By increasing the lithium content, less distorted niobium octahedra increase, indicating a niobium clustering. This change strongly affects the crystallization behavior. In the glasses x = 0 and x = 3, just above Tg, only nanocrystals of an unidentified phase are formed, while for x = 12 and x = 20 potassium lithium niobate (KLN) solid solutions with tetragonal tungsten–bronze structure crystallize by bulk nucleation. In these glasses, LiNbO3 crystallizes at higher temperature by surface nuclei. Ultimately, it is possible to produce nanostructured glasses based on KLN nanocrystals, by partial replacement of K by Li.