Explorations of New SHG Materials in Mercury Iodate Sulfate System**

Abstract

Through systematic experiments, two novel mercury iodate sulfates, namely, Hg 2 (IO 3 ) 2 (SO 4 )(H 2 O) and Hg 2 (IO 3 ) 2 (SO 4 ) were obtained. They crystallize in monoclinic space group C2 and C2/c, respectively. Hg 2 (IO 3 ) 2 (SO 4 )(H 2 O) exhibits the [Hg(IO 3 )] + polar cationic layer inherited from Hg(IO 3 ) 2 and the three-dimensional (3D) framework inherited from HgSO 4 . This enables Hg 2 (IO 3 ) 2 (SO 4 )(H 2 O) to generate a strong second harmonic generation (SHG) response of 6 times that of KH 2 PO 4 (KDP). The structure of Hg 2 (IO 3 ) 2 (SO 4 ) is very similar to that of Hg 2 (IO 3 ) 2 (SO 4 )(H 2 O), and they can be transformed into each other. Hg 2 (IO 3 ) 2 (SO 4 )(H 2 O) shows a large optical band gap of 3.98 eV and a high dehydration temperature of 250 °C. This study indicates that by reasonable design, the introduction of multiple functional groups into a compound may combine their advantages to achieve good overall optical performance.

Ba2Ga2F6(IO3)(PO4): the first fluoride-containing iodate-phosphate with a 1D [Ga2F6(IO3)(PO4)]4− helix chain

“…On the other hand, recent research results indicate that introducing oxyanions with wide HOMO–LUMO gaps, such as BO 3 3− , NO 3 − , SO 4 2− , PO 4 3− , etc ., into the iodates can yield novel mixed-anion iodates. 34–44 These crystals not only exhibit wide bandgaps but also strong SHG effects or large birefringence, such as Sc(IO 3 ) 2 (NO 3 ) (4 × KDP; 0.348@546 nm; 4.15 eV), 38 Be 2 (BO 3 )(IO 3 ) (7.2 × KDP; 0.172@1064 nm; 4.32 eV), 39 Na 7 (IO 3 )(SO 4 ) 3 (0.5 × KDP; 0.075@1064 nm; 4.83 eV) 41 and Cd 2 (IO 3 )(PO 4 ) (4 × KDP; 4.04 eV). 36 However, to date, there have been no reports of fluorinated mixed-anion iodates.…”

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

“…However, metal iodates usually exhibit narrow bandgaps (<4.0 eV), which might not be beneficial to effectively apply in the UV region. Recently, many studies put forward the view that the combination of an iodate group with another polar anion, such as BO 3 3– , NO 3 – , and F – , can significantly enlarge the bandgap and structural polarization of metal iodates. − Besides, the low dimensional (D) frameworks, including two-dimensional (2D) layers and 1D chains, are conducive to maximizing the birefringence. ,− For example, 2D Sc­(IO 3 ) 2 (NO 3 ) displays a wide bandgap (4.15 eV) and giant birefringence (0.366 @546 nm)…”