Molecular dynamics study on thermal conductivity of KH2PO4 with vacancy defects

Abstract

Potassium dihydrogen phosphate (KDP) crystals are crucial components in high-power laser systems, where thermal transport significantly affects their performance and reliability. This study investigates the thermal conductivity of KDP crystals, both with and without vacancy defects, using molecular dynamics simulations. The simulations reveal a pronounced anisotropy in thermal conductivity (κₐ ≈ κb > κc). The introduced vacancy defects suppress thermal conductivity to varying degrees by enhancing phonon scattering, with their potency ranking as VO > VK > VH. Oxygen vacancies (VO) are identified as the most detrimental, causing up to a ~86% reduction at 5% concentration, as they severely compromise the structural integrity of the [PO4]3- framework and hydrogen-bond network. This hierarchy of defect impacts provides direct guidance for defect control strategies, offering a complementary thermal perspective to existing optical studies and highlighting the importance of maintaining the stability of KDP in high-power multipulse laser systems.