Sintering behavior and properties of lithium stabilized sodium β'' - alumina ceramics with YSZ addition

In this study, investigations of sintering behavior and properties were performed on lithium-stabilized Na-β''-alumina (LiSBA) ceramics with and without 15?wt% 8?mol% Y₂O₃ stabilized ZrO₂ (8YSZ) addition synthesized by solid phase reaction. Changes of phase composition, relative density, and grain size in the ceramics sintered at different temperature were analyzed. It was shown that phase transformation in sintering ceramics was controlled by relationship between the Na₂O evaporation and Li⁺ ions stabilization, while microstructure evolution was controlled by pore-boundary interaction. LiSBA with YSZ addition (Zr-LiSBA) showed more significant variation of β'' phase fractions, slower grain growth and faster densification with increasing sintering temperature, which were caused by enhanced Na₂O evaporation and gas transport by oxygen ion conductor ZrO₂ as well as the drag effect by second phase particles of YSZ in Zr-LiSBA ceramics. Zr-LiSBA specimens sintered at optimized condition achieved higher Vickers microhardness and intermediate Na⁺ ion conductivity.