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

Abstract

A new beryllium-free deep-ultraviolet (DUV) nonlinear optical (NLO) material, β-Rb Al B O (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 PO and 0.4×β-BaB O , respectively, and exhibits a short absorption edge below 200 nm. β-Rb Al B O has a three-dimensional structure of corner-shared Al(BO ) O polyhedra. The discovery of β-RABO shows that through careful synthesis and characterization, replacement of KBe BO F (KBBF) by a Be-free DUV NLO material is possible.

Deep‐Ultraviolet Nonlinear Optical Crystal Cs2Al2(B3O6)2O: A Benign Member of the Sr2Be2(BO3)2O Family with [Al2(B3O6)2O]2− Double Layers

“…However, as‐grown KBBF and RBBF crystals are plate‐like habits with a serious layer tendency, severely hindering their further applications. To overcome the layer habit, the Sr 2 Be 2 (BO 3 ) 2 O (SBBO) family of NLO crystals were found, including SBBO, K 2 Al 2 (BO 3 ) 2 O (KABO), NaCaBe 2 (BO 3 ) 2 F, Rb 3 Ba 3 Li 2 Al 4 B 6 O 20 F (RBLABF), β‐Rb 2 Al 2 (BO 3 )O (β‐RABO), etc. In the SBBO family, the basic structural unit is the [M 2 (BO 3 ) 2 (O/F)] (M=Be, Al) double layer, composed of MBO 3 single layers through corner‐sharing O/F atom connections, which is beneficial for growing large size crystals.…”

“…Consequently, it has been the anion of choice for almost all reported prominent DUV NLO crystals . For example, β‐RABO crystal exhibits a pretty large NLO response (2 × KDP) due to its bilayer SBBO‐type (BO 3 ) 3− groups . However, for the optimization of KBBF‐type and SBBO‐type crystals, it seems very difficult to find better DUV NLO crystals by just sticking to the (BO 3 ) 3− group .…”

“…[1] Up to now,K Be 2 BO 3 F 2 (KBBF) [2] and RbBe 2 BO 3 F 2 (RBBF) [3] crystals are the only two practical DUVN LO crystalst hat can produce DUV coherent light by the directs econd harmonic generation (SHG) technique. However,a s-grown KBBF and RBBF crystals are plate-like habits with as erious layer tendency,s everely hindering their further applications.T oo vercomet he layer habit, the Sr 2 Be 2 (BO 3 ) 2 O( SBBO) [4] family of NLO crystals were found, including SBBO, K 2 Al 2 (BO 3 ) 2 O( KABO), [5] NaCaBe 2 (BO 3 ) 2 F, [6] Rb 3 Ba 3 Li 2 Al 4 B 6 O 20 F( RBLABF), [7] b-Rb 2 Al 2 (BO 3 )O (b-RABO), [8] etc. In the SBBO family,t he basic structuralu nit is the 2 1 [M 2 (BO 3 ) 2 (O/F)] (M = Be, Al) double layer,c omposed of MBO 3 single layers through corner-sharing O/F atom connections, which is beneficialf or growing large size crystals.…”

“…[7a, 11,12] For example, b-RABO crystal exhibits ap retty large NLO response (2 KDP) due to its bilayer SBBO-type (BO 3 ) 3À groups. [8] However,f or the optimization of KBBF-type and SBBO-type crystals, it seems very difficult to find better DUV NLO crystals by just stickingt ot he (BO 3 ) 3À group. [13] In contrast, multiple boron groups [14] whichc ould be even better DUV NLO genes than the (BO 3 ) 3À group are still barely investigated.…”

Prediction of Fluorooxoborates with Colossal Second Harmonic Generation (SHG) Coefficients and Extremely Wide Band Gaps: Towards Modulating Properties by Tuning the BO3/BO3F Ratio in Layers

“…[10,11] More challenges are that some of these properties are contradictory.S pecifically,S HG coefficients are inversely proportional to the band gap as shown in the sum-over-states formula. [13][14][15][16][17][18][19] To address the challenge,KBe 2 BO 3 F 2 (KBBF) [20] and Sr 2 Be 2 B 2 O 7 (SBBO) [21] are two outstanding available DUV NLO crystal, but the high toxicity and difficult in growing crystals seriously hinder their commercialization. [13][14][15][16][17][18][19] To address the challenge,KBe 2 BO 3 F 2 (KBBF) [20] and Sr 2 Be 2 B 2 O 7 (SBBO) [21] are two outstanding available DUV NLO crystal, but the high toxicity and difficult in growing crystals seriously hinder their commercialization.…”