Dual‐stage regulation of sintering kinetics in Nd/Ce‐doped YAG nanocrystalline ceramics

Abstract As a pivotal optical material, the microstructure of YAG (yttrium aluminum garnet) nanocrystalline ceramics directly determines their laser and luminescent performance. This study demonstrates that rare‐earth doping at grain boundaries significantly improves sintering behavior through a dual‐stage regulation mechanism: during the initial stage (relative density 65%–90%), dopants (Nd/Ce) suppress mass diffusion by stabilizing grain boundary structures; whereas in the intermediate stage (75‐85% relative density), they enhance diffusion by modifying grain boundary energy states. This kinetic regulation enables Nd‐doped samples to achieve 99.3% relative density at 1200°C (50°C lower than pure YAG) while maintaining grain size at 57–64 nm. The doped systems achieved the requisite thermodynamic state for successful two‐step sintering at significantly lower T 1 temperatures (Nd‐YAG: 1175°C, Ce‐YAG: 1175°C) compared with pure YAG (1200°C). The study confirms that Nd/Ce doping achieves coordinated densification‐grain growth control through grain boundary segregation, providing critical theoretical guidance for fabricating high‐performance transparent ceramics, particularly for developing novel Nd/Ce:YAG laser and scintillation ceramics.