KNa₂La₂(BO₃)₃: a shortite-type lanthanide borate exhibiting strong nonlinear optical activity induced by isolated [BO₃] triangles and distorted [LaO₉] polyhedra

Abstract

The targeted synthesis of ultraviolet (UV) nonlinear optical (NLO) materials with strong second-harmonic generation (SHG) activity and wide transparency window remains a formidable challenge. Herein, a prospective rare-earth borate UV...

Li13YGe4O16: A Mid-infrared Rare-Earth Germanate Nonlinear Optical Crystal Featuring a Broad Transmission Range and an Enlarged Band Gap

“…Previous studies have demonstrated that rare-earth cations bound to oxygen display flexible polyhedral configurations and are susceptible to local environmental distortion, which can be advantageous in the formation of compounds with noncentrosymmetric structures. In particular, those (Sc 3+ , Y 3+ , La 3+ , Gd 3+ , and Lu 3+ ) with closed-shell electronic configurations or half-occupied 4f orbitals − can effectively impede the d–d or f–f electronic transitions, thereby expanding the ultraviolet transmission range and widening the band gap. It is speculated that the combination of diverse building blocks with distinct functional attributes contributes to the rational design of NLO materials with overall properties.…”

Na3K6(CO3)3(NO3)2X·6H2O (X = NO3, Cl, Br): Exploring High-Performance UV Birefringent Crystals Induced by Coplanar π-Conjugated CO3 and NO3 Groups

“…Over the past decades, the BO 3 anionic group with π-conjugated molecular orbitals has long been regarded as an optimal structural unit for designing ultraviolet (UV) or deep-UV birefringent materials because of its higher anisotropic polarizability, wide band gap, and high UV transmittance, including α-BBO (0.122 at 532 nm; 189 nm), KNa 2 La 2 (BO 3 ) 3 (0.019 at 1 μm; 212 nm), CaZn 2 (BO 3 ) 2 (0.081 at 545 nm; < 190 nm), PbBe 2 B 2 O 6 (0.146 at 590 nm; 249 nm), Cd 8 (BO 3 ) 4 SiO 4 (0.053 at 546 nm; 254 nm), Na 3 AEZn 2 B 3 O 9 (AE = Mg, Ca) (0.045 at 1064 nm; 260 nm), etc. , As is well known, CO 3 and NO 3 groups are considered other two alternative anionic groups because they have similar π-conjugated planar triangular geometry configurations . Meanwhile, the anisotropic polarization of CO 3 and NO 3 is superior to that of BO 3 , and they can be also able to penetrate the UV or even deep-UV region; so CO 3 and NO 3 are more suitable for the construction of birefringent materials. − This motivates our interest in finding new UV birefringent crystals in the carbonate nitrate family.…”

Discovery of a new bimetallic borate with strong optical anisotropy activated by π-conjugated [B2O5] units

“…Researchers have discovered that birefringence can be effectively improved by introducing π-conjugated units placed in parallel. 25,39,40,43–45 Simultaneously, the UV cut-offs of borates containing alkali/alkaline-earth metals without d–d and f–f electron transitions are typically attained in the UV band range with significant transmittances and broad band gaps, such as LiB 3 O 5 (LBO), 46 KBe 2 BO 3 F 2 (KBBF), 47–49 and Ba 2 B 2 O 4 (BBO). 50,51 In addition, it has been demonstrated that the fluorination technique is a practical plan to change the nearly anisotropic tetrahedron's optical anisotropy.…”