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

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.