Interface analysis and diffusion behavior of YAG/Nd:LuAG heterojunction structure

YAG/Nd:LuAG heterojunction structure materials combined with crystals and ceramics were fabricated using a diffusion bonding method in which thermal bonding is applied before HIP treatment. The interface morphologies, microstructures, and optical properties of the samples were investigated. The results indicated that the YAG crystal was mixed and solid solutions were formed with the Nd:LuAG ceramic at the bonding interface for the existence of Si ions derived from the ceramic fabrication process. The diffusion process was investigated based on Fick's law. The diffusion coefficients of Lu and Y were fitted using theoretical calculations. In addition, Si and Nd ion segregation occurred at the grain boundaries. Finally, pore-free heterojunction structure materials were successfully fabricated with the transmittance of the sample reaching 83.26% at 1064 nm. This study reveals the migration and diffusion of ions in the crystal-ceramic heterojunction structure, which is an effective method for achieving low scattering loss and restraining active ion diffusion for the design of planar waveguides.