Abstract
Nonlinear-optical (NLO) metal aluminium phosphate crystal materials with deep-ultraviolet (DUV) transparent ability remain greatly unexplored. Herein, mixed alkali/alkaline-earth metal aluminium phosphate DUV NLO crystal Na_2Ca_(17)Al_2(PO_4)_(14) was successfully synthesized through the high-temperature molten technology. Na_2Ca_(17)Al_2(PO_4)_(14) features a 3D Ca-cluster-constructed framework by the stacking of Ca_6O_(36) and (Ca/Na)_3O_(19) clusters, which is filled by isolated A1(PO_4)_6 clusters and isolated PO_4 tetrahedra. Na_2Ca_(17)Al_2(PO_4)_(14) exhibits a short UV absorption edge below 190 nm, phase-matching behavior with strong NLO effect of 0.9 × KDP, high thermal stability. First-principles calculations indicate that the optical properties of Na_2Ca_(17)Al_2(PO_4)_(14) derive primarily from the Ca-O groups, rather than Al-O and P-O traditional groups. The work may further promote the exploration of new DUV NLO aluminium phosphate crystal materials.