Deep-Ultraviolet Mixed-Alkali-Metal Borates with Induced Enlarged Birefringence Derived from the Structure Rearrangement of the LiB₃O₅

Abstract

By introduction of K + , Rb + , and Cs + cations into the classical commercial nonlinear optical crystal LiB 3 O 5 (LBO), the series of novel mixed-alkali-metal borates Li 2 . 6 K 0 . 4 [B 5 O 8 (OH) 2 ] (K-LBO), Li 2.85 Rb 0.15 [B 5 O 8 (OH) 2 ] (Rb-LBO), and Li 2.9 Cs 0.1 [B 5 O 8 (OH) 2 ] (Cs-LBO) have been obtained under hydrothermal conditions. The steric hindrance effect generated by the introduction of large alkali-metal cations and partial substitution of small Li + cations broke the three-dimensional (3-D) framework of [B 3 O 7 ] 5− borate−oxygen clusters in LBO and resulted in a structure rearrangement to produce infrequent [B 10 O 26 ] 22− 2-D layers. The unique layered structure induced an increase in birefringence in A-LBOs (A = K, Rb, Cs), which is favorable for phase matching during second-harmonic generation. All three compounds are potential deep-ultraviolet nonlinear optical materials, which was proved by UV−vis−NIR diffuse reflectance spectroscopy and second-harmonic-generation measurements.

Cd4InO(BO3)3: A New Nonlinear Optical Crystal Exhibiting Strong Second Harmonic Generation Effect and Moderate Birefringence

“…The Infrared Spectrum of CIBO is shown in Figure S2. The peaks at 1174 cm −1 and 933 cm −1 can be assigned to the asymmetric stretching vibrations of the BO 3 group [60,61]. The peaks located at 707 cm −1 and 583 cm −1 were assigned as the bending vibrations of BO 3 groups.…”

“…As shown in Table S5, the total net dipole moment of BO 3 groups in the unit cell yield 1.025 Debey (D), which is approximately 54.45% of its optimal value. Meanwhile, the Cd−O polyhedra also contributes to the dipole moment of 0.878 D. Therefore, the synergistic effects of the NLO-active BO 3 groups and the d 10 Cd 2+ cations in CIBO endowed the material with a large SHG effect, which is comparable with LiB 3 O 5 [60] and Cd 5 (BO 3 ) 3 F [73].…”

Syntheses, structures and optical properties of two B3O7 cluster-based borates

“…Meanwhile, alkali and alkaline earth metals have no d–d or f–f electron transitions in the UV and DUV regions, offering wide UV and DUV transparency ranges. 38,39 Additionally, the spherical coordination of alkali and alkaline earth metals can increase the possibility of acentric structures by reducing the symmetrical influences from centrosymmetric guest templates to acentric host frameworks. 11 Up to date, most of the UV/DUV NLO borates are alkali and alkaline earth metal borates, including the typical β-BaB 2 O 4 (BBO), LiB 3 O 5 (LBO) and CsLiB 6 O 10 (CLBO), 40–42 and the newly reported LiBa 3 (OH)[B 9 O 16 ][B(OH) 4 ], 2 Li 2 CsB 7 O 10 (OH) 4 (ref.…”

Tin Chloride Sulfates A3Sn2(SO4)3–xCl1+2x (A = K, Rb, Cs; x = 0, 1) as Multifunctional Optical Materials

“…Functional materials containing a noncentrosymmetric (NCS) crystal framework, namely, being short of a center of symmetry, have drawn tremendous attention due to their fascinating functional properties: for instance, second-harmonic generation (SHG) properties, piezoelectricity, pyroelectricity, and ferroelectricity. − An effective approach that has been proved to produce NCS compounds is the employment of asymmetric SHG-active building units in the initial synthesis. These asymmetric units include anion groups with a planar π-conjugated structure and a highly anisotropic shape (BO 3 3– , − CO 3 2– , − NO 3 – , , C 3 N 3 O 3 3– , − etc. ), d 0 transition-metal-centered polyhedra with strong structural distortions, such as WO 6 , NbO 6 and VO 6 , , d 10 cation (Zn 2+ , Cd 2+ ) centered polyhedra with highly polar displacement, − and especially cations with stereochemically active lone pairs (Pb 2+ , , Bi 3+ , , etc.).…”