LiGaF2(IO3)2: A mixed-metal gallium iodate-fluoride with large birefringence and wide band gap

Abstract

The first mixed alkali-metal gallium iodatefluoride, namely, LiGaF 2 (IO 3 ) 2 , was successfully obtained under hydrothermal conditions. The structure of LiGaF 2 (IO 3 ) 2 features a novel two-dimensional (2D) [GaF 2 (IO 3 ) 2 ] − layer composed of [Ga 2 F 4 (IO 3 ) 6 ] 4− dimers further bridged by (IO 3 ) − groups. LiGaF 2 (IO 3 ) 2 exhibits a wide band gap of 4.33 eV, corresponding to the ultraviolet (UV) absorption edge of 230 nm. Calculations of linear optical property revealed that LiGaF 2 (IO 3 ) 2 has a remarkably large birefringence of 0.181 @1064 nm and 0.206@532 nm, indicating that it is a potential birefringent material that could be used from visible to UV region. This study provides a new method for the future discovery of promising optical crystals.

K3V2O3F4(IO3)3: a high-performance SHG crystal containing both five and six-coordinated V5+ cations

“…Of great importance are metal iodates which can exhibit high SHG response (d ij > 10 × KDP) or/and large birefringence (Δn > 0.15 @1064 nm). [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Recently, two new effective routes to high performance metal iodate SHG crystals have been developed. One is using the 2D [Bi 2 O 2 ] 2+ layer and 3D [BiF 2 ] + cationic network for confined the iodate anions to be arranged in a favorable addictive fashion, which has successfully led to the discovery of BiO(IO 3 ) (12.5 × KDP) 20 and Bi(IO 3 )F 2 (11.5 × KDP, 0.22 @1064 nm) 21 .…”

Mg(H2O)6[(IO2(OH))2(IO3)]2: a new iodate with a very large band gap and optical anisotropy

“…Thus, to broaden the band gaps, iodates containing main group metal cations such as Ba 2 [GaF 4 (IO 3 ) 2 ]IO 3 , LiGaF 2 (IO 3 ) 2 , and Ba[InF 3 (IO 3 ) 2 ] have been prepared, where the combination of iodates and distorted octahedra groups was proven to be an effective way to design interesting birefringent materials with large band gaps. [39][40][41] In this paper, we have explored the Mg 2+ cation containing iodate system to discover new birefringent materials. By doing so, a new magnesium iodate, Mg(H 2 O) 6 [(IO 2 (OH)) 2 (IO 3 )] 2 , has been successfully obtained via the facile aqua-solution method at room temperature.…”

ZrF2(IO3)2 and RbGaF3(IO3): Two Promising Birefringent Crystals Featuring 1D Metal-Fluoride Cationic Chains and Wide Bandgaps

“…Notably, the contribution from the orbitals of Rb and Ga atoms is negligible, which also can be verified in other reported alkali/alkaline-earth Ga-centered iodate-fluorides (α-and β-Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 ), LiGaF 2 (IO 3 ) 2 , NaGaI 3 O 9 F, etc.). 36,38,58 Both ZrF 2 (IO 3 ) 2 (C2/c) and RbGaF 3 (IO 3 ) (Pnma) belong to the biaxial crystal containing three principal axes with refractive indices of n x , n y , and n z (Figure 6). For ZrF 2 (IO 3 ) 2 , its refractive index features n x ≈ n z ≫ n y .…”

“…For RbGaF 3 (IO 3 ), in Figure 6b, its birefringence at 1064 nm is 0.174, which is comparable with that of LiGaF 2 (IO 3 ) 2 (0.181 @1064 nm) but is larger than those of α/β-Ba 2 [GaF 4 (IO 3 ) 2 ](IO 3 ) (0.126 and 0.135 @1064 nm) and its parent compound, 3D RbMoO 3 (IO 3 ) (0.083 @1064 nm). 36,38,52 To investigate the birefringence origin of ZrF 2 (IO 3 ) 2 and RbGaF 3 (IO 3 ), calculations of the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) have been performed as shown in Figures S5 and S6. For ZrF 2 (IO 3 ) 2 , the HOMO and LUMO exhibit clear anisotropy of electron densities, which are mostly contributed by the I−O bonds from the highly distorted IO 3 groups (Figure S5).…”