Characterization and criteria of phase transformations and lattice slipping in potassium dihydrogen phosphate crystals

Being an important nonlinear optical material, potassium dihydrogen phosphate (KDP) has been widely used in many technological fields such as laser frequency conversion and high-speed Q-switching. Nevertheless, KDP is one of the most difficult-to-handle materials because it is prone to phase transformations under mechanical loading during component fabrication. This study investigated the mechanisms of phase transformations and microstructural lattice slipping in KDP with the aid of molecular dynamics (MD) analysis. A fundamental structural characterization method was established to identify the structural changes, enabling the determination of the corresponding trigger criteria. The results showed that various phase transformations can be initiated under a range of mechanical loading conditions. Microstructural lattice slipping can be nucleated via different mechanisms. These findings provide insights for developing damage-free manufacturing processes of ultraprecision KDP components.