Sintering of lixiviated nano glass-ceramics: An original route to elaborate transparent ceramics

Abstract

We report the elaboration of translucent ZnGa2O4 ceramics by an innovative process, the sintering by Spark Plasma Sintering (SPS) of spinel ceramic powder obtained by the lixiviation of glass-ceramics. Indeed, a selective dissolution of the silica-rich glass matrix allows isolating ZnGa2O4 nanocrystals embedded in the silicate glass-ceramic. This glass-ceramic is elaborated from the parent glass of composition 55 SiO2 - 5 Na2O - 17 ZnO - 23 Ga2O3 (%mol) that undergoes a subsequent heat-treatment at 1100 °C under air leading to the crystallization of zinc gallate spinel nanocrystals with size in the 20–60 nm range. Lixiviated nanocrystals are collected and sintered by SPS to get a bulk ceramic. While the transmittance of this ceramic is only 60% at 4.5 µm, which is lower than the theoretical transmittance (82.5%), these first results are still promising and pave the way to new transparent ceramic processing route. Indeed, glass crystallization combined with selective lixiviation process is a powerful, non-conventional elaboration process that can further allow the stabilization and isolation of metastable crystalline phases with interesting functional properties.