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

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 $\mathrm{\infty }3\left[{\mathrm{Al}}_3{\mathrm{P}}_6{\mathrm{O}}_{20}\right]$ 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.