Na₂Hg₃M₂S₈ (M = Si, Ge, and Sn): New Infrared Nonlinear Optical Materials with Strong Second Harmonic Generation Effects and High Laser-Damage Thresholds

Abstract

A new family of noncentrosymmetric isostructural compounds, Na2Hg3M2S8 (M = Si, Ge, and Sn), was successfully synthesized. They crystallize in the tetragonal space group P4̅c2 with Z = 2. Their major structures are composed of infinite cross-connected ∞ (HgS3) n chains and isolated [MS4] ligands and show the interesting tunnel features. Interestingly, compared with the structures of A2Hg3M2S8 (A = alkali metal, Na–Cs), it can be found that the structural symmetries show a gradually rising tendency from Cs to Na analogues as a result of cation size effect, which rarely exists in quaternary alkali metal chalcogenides. Property measurements show that title compounds exhibit strong second harmonic generation (SHG) effects with a phase-matching behavior at 2.09 μm, wide transparency range in the infrared (IR) region, and large laser-damage thresholds (LDTs). Remarkably, Na2Hg3Si2S8 and Na2Hg3Ge2S8 achieve the suitable balance between large SHG effects (1.3 and 2.2 × benchmark AgGaS2) and high LDTs (4.5 and 3 × AgGaS2), respectively, and can be expected to be potential nonlinear optical (NLO) candidates in the IR region. Moreover, band structures and NLO properties of title compounds are also theoretically studied, and the calculated NLO coefficients are consistent with the experimental observations.

Li2HgMS4 (M = Si, Ge, Sn): New Quaternary Diamond-Like Semiconductors for Infrared Laser Frequency Conversion

“…The results show that all of them exhibit the wide IR transmission regions, such as 2.5-19 µm (530 cm −1 ) for Li 2 HgSiS 4 , 2.5-22 µm (450 cm −1 ) for Li 2 HgGeS 4 , and 2.5-23.5 µm (425 cm −1 ) for Li 2 HgSnS 4 , which cover the two important atmospheric windows (3-5 and 8-12 µm) that can be used in telecommunications, laser guidance, and explosives detection. Note that the IR absorption edges gradually get longer from the Si to Sn compounds, which are consistent with the IR data for other related mental chalcogenides [61]. Although the measured IR absorption data on powder samples have some deviations with the results on single-crystals, they can give the preliminary assessment for the transmission region of IR materials.…”

“…From this table, it can be found that the title compounds have great LDTs, such as 91.6 for Li2HgSiS4, 70.6 for Li2HgGeS4, and 30.5 MW/cm 2 for Li2HgSnS4, and are about 3.0, 2.3, and ~1 times that of powdered AgGaS2 (29.6 MW/cm 2 ), respectively. Moreover, Li2HgSiS4 and Li2HgGeS4 are comparable to those of PbGa2GeSe6 (3.7 × AgGaS2) [51], Na2In2GeS6 (4.0 × AgGaS2) [56], Na2Hg3Ge2S8 (3 × AgGaS2) [61], and SnGa4Se7 (4.6 × AgGaS2) [52]. Therefore, Li2HgSiS4 and Li2HgGeS4 can be expected to have application with high-power lasers, compared with the commercial IR NLO materials.…”

A High Laser Damage Threshold and a Good Second-Harmonic Generation Response in a New Infrared NLO Material: LiSm3SiS7

“…IR and Raman spectra ( Figure 2) show that LiSm 3 SiS 7 has a wide transmission range in the IR region (up to 21 µm) that covers two critical atmospheric windows (3-5 and 8-12 µm), which is comparable to those reported for powdered BaGa 4 Se 7 (~18 µm) [35], AgGaS 2 (~23 µm) [30], Li 2 CdGeS 4 (~22 µm) [70], and Na 2 Hg 3 Si 2 S 8 (~20 µm) [47]. Moreover, the bandgap (2.83 eV) of LiSm 3 SiS 7 is larger than that of commercial AgGaS 2 crystal (2.56 eV) [30]; thus, LiSm 3 SiS 7 may have a higher laser damage resistance since the LDT is generally proportional to the bandgap for one material.…”

Coexistence of Strong Second Harmonic Generation Response and Wide Band Gap in AZn4Ga5S12 (A=K, Rb, Cs) with 3D Diamond‐like Frameworks

“…[29][30][31][32][33] The powder SHG properties were estimated on polycrystalline samples by using a2 050 nm Q-switch laser based on the Kurtz and Perry method. Moreover,t he relative LIDTsd ata of these polycrystallinec ompounds are about 36 AGS at the range of 150-210 mmp article size (Figure4b), which are larger than those of Na 2 Hg 3 Si 2 S 8 (4.5 AGS), [41] Na 2 ZnGe 2 S 6 (6.0 AGS), [22] Na 2 BaGeS 4 (8.0 AGS), [15] Pb 7 O 8 Cl 18 (12.8 AGS), [37] Ba 4 ZnGa 4 Se 10 Cl 2 (17.0 AGS), [42] and [Rb 3 Br][Ga 3 PS 8 ]( 29.0 AGS). Moreover,t he relative LIDTsd ata of these polycrystallinec ompounds are about 36 AGS at the range of 150-210 mmp article size (Figure4b), which are larger than those of Na 2 Hg 3 Si 2 S 8 (4.5 AGS), [41] Na 2 ZnGe 2 S 6 (6.0 AGS), [22] Na 2 BaGeS 4 (8.0 AGS), [15] Pb 7 O 8 Cl 18 (12.8 AGS), [37] Ba 4 ZnGa 4 Se 10 Cl 2 (17.0 AGS), [42] and [Rb 3 Br][Ga 3 PS 8 ]( 29.0 AGS).…”