Beryllium‐Free β‐Rb₂Al₂B₂O₇ as a Possible Deep‐Ultraviolet Nonlinear Optical Material Replacement for KBe₂BO₃F₂

A new beryllium‐free deep‐ultraviolet (DUV) nonlinear optical (NLO) material, β‐Rb 2 Al 2 B 2 O 7 (β‐RABO), has been synthesized and characterized. The chiral nonpolar acentric material shows second‐harmonic generation (SHG) activity at both 1064 and 532 nm with efficiencies of 2×KH 2 PO 4 and 0.4×β‐BaB 2 O 4 , respectively, and exhibits a short absorption edge below 200 nm. β‐Rb 2 Al 2 B 2 O 7 has a three‐dimensional structure of corner‐shared Al(BO 3 ) 3 O polyhedra. The discovery of β‐RABO shows that through careful synthesis and characterization, replacement of KBe 2 BO 3 F 2 (KBBF) by a Be‐free DUV NLO material is possible.