Theoretical Prediction of Cluster Configuration Transition and Electro-Optical Properties of YP Defects in KH2PO4

Abstract

The corrected defect formation energies, crystal structures, electronic behaviors, and optical properties of YP isolated defects and defect clusters YP+VO were studied using density functional theory. The results indicate that configuration transitions of point defects and cluster defects are encouraged under different oxygen partial pressures. Unlike Fe3+ or Cr3+, the defect formation energy of the YP defect center compensation by the nearest-neighbor VO is the lowest, suggesting that under oxygen-poor conditions, the defect cluster of YP defect composed of the nearest-neighbor O vacancy may be the main type of Yttrium-like trivalent rare earth metal atomic impurities in the crystal. Electronic behaviors show that the stronger coupling strength between the rare-earth metal Y and O and the bonding between H and O are the main reasons for the different ease of formation of different defect cluster structures. Thus, the interatomic interactions between the [YP+VO] cluster and isolated defect were analyzed, and an attempt was made to explain certain experimental phenomena. Finally, their optical properties were calculated, and the more pronounced defect levels and larger Stokes redshift indicate that cluster structures have a greater impact on the thermodynamic absorption of the crystal. New understanding has been given to the effects of laser pre-treatment on KDP crystals. This suggests that an oxygen-rich atmosphere may improve the LIDT of KDP crystals containing trivalent rare-earth metal impurities, providing a theoretical basis for enhancing the optical properties of the crystal.