ABSTRACT
An unusual O/F ordered d0 transition metal fluoroantimonite, namely, K2SbMoO2F7, 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 A2SbMoO2F7 (A = Rb, Cs). These three new compounds exhibit two different structures, although all of the structures were made of [SbMoO2F7]2- chains formed by SbF5 square pyramids and MoO2F4 octahedrons. A transparent single crystal of K2SbMoO2F7 with dimensions of 7.0 × 5.0 × 1.0 mm3 has been successfully grown by the aqueous solution volatilization method. The UV-vis-MIR transmission spectrum showed that K2SbMoO2F7 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.
ABSTRACT
The first examples of zirconium fluoroantimonites, namely, K3ZrF4(SbF4)(SbF5) and K8(ZrF6)(Sb2Zr2F20), have been successfully synthesized by facial hydrothermal reactions. K3ZrF4(SbF4)(SbF5) features a unique 1D (ZrSb2F13)3- double-chain structure, while K8(ZrF6)(Sb2Zr2F20) displays a special 0D construction composed of Zr2Sb2F20 tetranuclear clusters and isolated ZrF6 octahedra. The two fluorides can exhibit a broad transparency range with almost no absorption peaks from ultraviolet to near-IR. For K8(ZrF6)(Sb2Zr2F20), a phase transformation was found before decomposition. The band structures, density of states, and linear-optical properties for the title compounds were also obtained.
ABSTRACT
Two new indium iodate-nitrates, In(IO3)2(NO3) (1) and [In(IO3)(OH)(H2O)](NO3) (2), were rationally designed through the integration of hybrid anionic functional units. They exhibit large birefringences (1, 0.269; 2, 0.188, at 532 nm) and wide band gaps (1, 4.08 eV; 2, 4.39 eV), which is attributed to the synergistic effect of two types of birefringence-active units, namely, lone-pair IO3 and π-conjugated NO3 anionic groups. Through the substitution of OH and H2O of 2 with IO3, the hydrogen bonds of 2 are eliminated and the birefringence of 1 is greatly enhanced, highlighting the intriguing role of isovalent substitution in the discovery of fascinating optical materials.
ABSTRACT
Fluorine, as the most electronegative element, can replace the oxygen ligands of functional groups under given conditions. These fluoride groups are more or less different from the pure oxide groups in composition, symmetry, polarizability, transmittancy, etc. The rational use of these differences is expected to improve the probability of noncentrosymmetric structures and the comprehensive performance of second-harmonic-generation (SHG) materials. In this feature article, we introduce the recent developments in fluoride selenite and tellurite SHG materials together with highlighting our contributions, including Se(IV) and Te(IV) compounds with (i) d0 transition metal oxyfluoride octahedron, (ii) IIIA metal oxyfluoride octahedron, (iii) fluoride lone pair cation polyhedron, and (iv) other fluoride polyhedron. The future perspectives of fluoride selenite and tellurite SHG materials are also discussed.
