Highly Birefringent d⁰ Transition Metal Fluoroantimonite in the Mid Infrared Band: Order–Disorder Regulation by Cationic Size

Abstract

An unusual O/F ordered d 0 transition metal fluoroantimonite, namely, K 2 SbMoO 2 F 7 , has been created by the cationic size effect of alkali metals. It features the largest birefringence of 0.220@550 nm among inorganic antimonites with a halogen element, which is an order of magnitude larger than the disordered A 2 SbMoO 2 F 7 (A = Rb, Cs). These three new compounds exhibit two different structures, although all of the structures were made of [SbMoO 2 F 7 ] 2− chains formed by SbF 5 square pyramids and MoO 2 F 4 octahedrons. A transparent single crystal of K 2 SbMoO 2 F 7 with dimensions of 7.0 × 5.0 × 1.0 mm 3 has been successfully grown by the aqueous solution volatilization method. The UV−vis−MIR transmission spectrum showed that K 2 SbMoO 2 F 7 can display excellent transmittance in the range of 0.5−5.0 μm and 6.0−9.8 μm, indicating its application potential as a birefringent material in the mid infrared band. This work offers a fresh approach to the design and synthesis of mid infrared birefringent materials.

Hg3Se(SeO3)(SO4): A Mixed-Valent Selenium Compound with Mid-Infrared Transmittance Obtained by In Situ Reaction

“…Exploring new material systems is of great importance, because it contributes to expand the chemical space and discovery novel materials with unique properties and potential applications. − By investigating new inorganic compound systems, researchers can uncover unprecedented structural motifs, understand the relationships between structures and properties, and potentially develop advanced materials for various technological applications. − Selenites have garnered the attention of scientists due to their unique physical and chemical properties. − They possess stereochemically active lone-electron pairs, making them promising candidates of nonlinear optical (NLO) and birefringent materials . Over the past few decades, research on selenite compounds has identified over a thousand different chemical entities.…”

Hg4(Te2O5)(SO4): A Giant Birefringent Sulfate Crystal Triggered by a Highly Selective Cation

“…The first is the large anisotropy of the TeO 3 triangular pyramids and the linear O–Hg–Hg–O groups. It is reported that the lone pair electrons of tellurite groups point to the minimum refractive index direction and the maximum refractive index direction is perpendicular to the lone pair electrons. , For the linear groups, the maximum refractive index direction parallels the line. These two groups can display strong anisotropy in the refractive indices.…”

Dual-Anion Strategy Induces Dual Enhancement Toward Ultrashort Phase-Matching Wavelength in Deep-UV Transparent d0 Transition Metal Oxyfluorides

“…The anionic groups containing d 0 transition metals with second-order Jahn–Teller (SOJT) distortions are one of the most commonly used NLO-active groups in visible light region, as the out-of-center distortions (e.g., NbO 6 in LN and TiO 6 in KTP) arising from metal dπ–oxygen pπ orbital interactions have the potential to induce noncentrosymmetric (NCS) structures and generate strong SHG intensities. − The SOJT distortion also leads to increased polarization anisotropy, making birefringence capable of better PM ability . Extensive attempts including Nb 2 O 3 (IO 3 ) 2 (SO 4 ) (6 × KDP, Δ n = 0.22), LiZrTeO 6 (2.5 × KDP, Δ n = 0.06), BaTeMo 2 O 9 (15 × KDP), BaTeW 2 O 9 (12.5 × KDP), K­(VO) 2 O 2 (IO 3 ) 3 (20 × KDP), BaNbO­(IO 3 ) 5 (14 × KDP), and Cs 3 Nb 5 GeO 16 (Δ n = 0.19) demonstrate success in the visible to IR light regions.…”

“…41−44 The SOJT distortion also leads to increased polarization anisotropy, making birefringence capable of better PM ability. 45 × KDP, Δn = 0.22), 46 LiZrTeO 6 (2.5 × KDP, Δn = 0.06), 47 BaTeMo 2 O 9 (15 × KDP), 48 BaTeW 2 O 9 (12.5 × KDP), K(VO) 2 O 2 (IO 3 ) 3 (20 × KDP), 49 BaNbO(IO 3 ) 5 (14 × KDP), 50 and Cs 3 Nb 5 GeO 16 (Δn = 0.19) 51 demonstrate success in the visible to IR light regions. However, the high distortion usually corresponds to limited band gaps, which seriously influences transparency in short wavelength regions.…”