AAl3P6O20 (A = Rb, Cs): Two deep-ultraviolet transparent nonlinear optical materials designed by aliovalent substitution

● AAl 3 P 6 O 20 (A = Rb, Cs) were designed from Ba 5 P 6 O 20 by aliovalent substitution. ● They exhibit the shortest cutoff edges (<190 nm) among Al-based phosphates. ● Flexible P 3 O 10 groups are favorable for designing NCS crystal structures. We obtained two Al-based triphosphates AAl 3 P 6 O 20 (A = Rb, Cs) by aliovalent substitution and they have the shortest cutoff edges (<190 nm) among Al-based phosphates. Two deep-ultraviolet (DUV) transparent nonlinear optical (NLO) materials, AAl 3 P 6 O 20 (A = Rb, Cs) ( I, II ), have been elaborately designed from Ba 5 P 6 O 20 by aliovalent substitution strategy. Both of compounds crystallize in noncentrosymmetric (NCS) C222 1 (No. 20) space group with three-dimensional (3D) ∞ 3 Al 3 P 6 O 20 skeleton. The cutoff edges of I and II are lower than 190 nm, which are the shortest ones among the reported Al-based phosphates. In addition, their syntheses, thermal properties, NLO performances are discussed and the first-principles calculation elucidates the origin of the optical properties. This study shows that aliovalent substitution is an effective synthetic route for designing DUV transparent Al-based phosphates NLO materials.