Cd₄SiQ₆ (Q = S, Se): Ternary Infrared Nonlinear Optical Materials with Mixed Functional Building Motifs

Abstract

Two ternary infrared nonlinear optical materials Cd4SiS6 (1) and Cd4SiSe6 (2) with polar space group Cc were obtained by mixing d10 configurations-central tetrahedra motifs and nonlinear optical (NLO)-active distorted MIVQ4 tetrahedra motifs in a non-alkaline earth metals-containing system. They exhibited an interesting three-dimensional (3D) framework structure, and millimeter-level single crystals were successfully grown by a chemical transport reaction. Comprehensive optical measurements indicated that they achieve coexistence of good second-harmonic generation (SHG) responses (1.3 and 1.9 × AgGaS2 at 74–106 μm particle size) and high laser-induced damage thresholds (8.6 and 7.1 × AgGaS2 at 1064 nm laser) and wide infrared (IR) transparent regions (0.45–17.6 μm for 1, 0.64–20.3 μm for 2). Furthermore, theoretical studies revealed that their SHG effects originate from two functional building motifs (FBMs) CdQ4 and SiQ4 tetrahedra, shedding light on the exploration of new IR NLO materials with mixed FBMs.

α-Ca2CdP2 and β-Ca2CdP2: Two Polymorphic Phosphide-Based Infrared Nonlinear Crystals with Distorted NLO-Active Tetrahedral Motifs Realizing Large Second Harmonic Generation Effects and Suitable Band Gaps

“…Besides, α-Ca 2 CdP 2 and β-Ca 2 CdP 2 exhibited stronger SHG intensities than AgGaS 2 (∼1.41 and 3.28× that of AgGaS 2 , respectively, among particle sizes of 150–200 μm at 2050 nm laser) and could be potential IR NLO materials. As a contrast, the title compounds had comparable or even larger SHG intensities than some Cd-based IR NLO materials, such as Cd 4 GeS 6 (1.1× that of AgGaS 2 ), Cd 4 SiS 6 (1.3× that of AgGaS 2 ), LiCd 3 PS 6 (0.8× that of AgGaS 2 ), Li 2 CdGeS 4 (0.4× that of AgGaS 2 ), Li 2 CdSnS 4 (0.6× that of AgGaS 2 ), and Na 2 CdGe 2 S 6 (0.8× that of AgGaS 2 ) . As illustrated in Table , α-Ca 2 CdP 2 and β-Ca 2 CdP 2 performed well in regard to both their SHG effects and band gaps compared to some known IR NLO materials, thus achieving a relative balance between the SHG effects and band gaps.…”

“…), and d 10 transition metals (Zn 2+ , Ag + , Cd 2+ , etc. ) − have been considered to be introduced to IR NLO phosphides. Because these cations benefit from the second-order Jahn–Teller (SOJT) effect or a large polar displacement, they easily form asymmetrical polyhedra and are thus favorable for generating larger SHG responses.…”

Li2Mg2Si2S6 and Li2Mg2Ge2S6: Two nonlinear optical sulfides featuring a unique, polar trigonal structure incorporating ethane‐like anions

“…[2] Na 2 Hg 3 Si 2 S 8 and Na 2 Hg 3 Ge 2 S 8 feature tetrahedral (TS 4 ) 4À anions and present strong phasematching (PM) SHG responses of 2.3 and 2.2 × AGS and elevated LIDTs of 4.5 and 3 × AGS, respectively. [3] Distorted (TS 4 ) 4À units are found in Cd 4 SiS 6 [4] and Cd 4 GeS 6 , [5] which give rise to PM SHG signals of 1.5 and 1.1 × AGS and impressive LIDTs of 8.6 and 3.6 × AGS, respectively. Ba 2 Ga 8 GeS 16 , which contains mixed (Ga/ Ge)S 4 and GaS 4 tetrahedra exhibits a decent PM SHG response, with a χ (2) of 6.6 pm/V and a remarkable LIDT of 22 × AGS.…”

“…Metal thiosilicates and thiogermanates are attractive classes of solid-state materials with a rich structural diversity. In these compounds, various tetrel-sulfur anionic building units can be stabilized, including (TS 4 ) 4À , [1][2][3][4][5][6][7][8][9] (T 2 S 6 ) 4À , [10,11] (T 2 S 6 ) 6À , [12][13][14] (T 2 S 7 ) 6À , [15,16] and (T 4 S 10 ) 4À , [17,18] where T = Si or Ge. The tetrahedral (TS 4 ) 4À unit is the most prevalent of these anions in condensed inorganic phases.…”

LaBS3 revisited: a promising mid-infrared nonlinear optical material

“…The thermogravimetric analysis (TGA) and the differential scanning calorimetry (DSC) curve (Figure S4, ESI †) show that LBS is stable up to at least 700 1C. Its melting point is about 713 1C, which is higher than those of ASb 5 S 8 (A = K, Rb; 400 1C), Cd 4 SiQ 6 (Q = S, Se; 710 1C, 362 1C), and Zn 3 P 2 S 8 (594 1C), [33][34][35] but much lower compared to that of AGS (998 1C). 36 According to the IR spectrum (Fig.…”