HgCuPS₄: An Exceptional Infrared Nonlinear Optical Material with Defect Diamond-like Structure

Abstract

Infrared nonlinear optical (IR-NLO) crystals possessing excellent comprehensive performance are highly desirable, yet their preparation remains extremely challenging. Particularly, inorganic chalcogenides with diamond-like (DL) structures provide a tunable material platform for their structural design and functional control. In this work, a strategy involving the construction of chalcogenides with DL structures using the strong polarizability of metal cations has been put forward; thus, a quaternary Hg-containing metal sulfide HgCuPS 4 has been successfully discovered by the high-temperature solid-state technology. A remarkable structural characteristic of HgCuPS 4 is the three-dimensional (3D) defect DL framework constructed by vertex-sharing alignments of asymmetric building motifs (ABMs). The combination of the unique defect DL structure and the strong polarizability of the Hg 2+ cations enables such compound to achieve phase matchability in the IR range with a high laser-induced damage threshold (4.2 × AgGaS 2 ) and a strong second harmonic generation response (d ij = 6.5 × AgGaS 2 ), the best among the quaternary DL chalcogenides reported so far. Moreover, the detailed local dipole moment calculations and the theoretical results based on the length-gauge formalism elucidate that the very high d ij value of HgCuPS 4 originates from the combined effects of distorted [HgS 4 ], [CuS 4 ], and [PS 4 ] ABMs, that is, the 3D defect DL structure. This discovery can effectively help understand and design other promising defect DL metal chalcogenides toward future high-performing IR-NLO applications.

Mg2In3Si2P7: A Quaternary Diamond-like Phosphide Infrared Nonlinear Optical Material Derived from ZnGeP2

“…As Figure b shows, the 0-level IR transparent range of MISP was 0.56–16.4 μm, which was significantly broader than that of state-of-the-art ZnGeP 2 (0.7–12.5 μm), AgGaS 2 (0.5–13 μm), CdSiP 2 (0.58–10 μm), BaGa 4 S 7 (0.35–13.7 μm), BaGa 2 GeS 6 (0.41–11.8 μm), LiGaS 2 (0.32–11.6), LiGaSe 2 (0.37–13.2), LiInS 2 (0.41–12.0), and LiInSe 2 (0.47–13.3). ,,− Remarkably, in the 0.7–10 μm region, MISP had good optical transparency (>50%) without absorption, which indicated that it could be effectively pumped using the mature commercial 1.064, 2.090, and 9.6 μm laser source. Two obvious phonon absorption peaks at 10.5 and 11.9 μm were observed, which are common phenomena in chalcogenide and pnictide IR NLO crystals. − Significantly, the phonon absorption band was longer that those of ZnGeP 2 (∼9.0 μm), CdSiP 2 (6.7 μm), BaGa 4 S 7 (∼9.0 μm), and BaGa 2 GeS 6 (∼8.0 μm). The phonon spectrum of MISP, determined by Raman scattering on powder samples, are presented in Figure S6a.…”

AXHg3P2S8 (A = Rb, Cs; X = Cl, Br): New Excellent Infrared Nonlinear Optical Materials with Mixed‐Anion Chalcohalide Groups of Trigonal Planar [HgS2X]3− and Tetrahedral [HgS3X]5−

“…Among the various IR NLO‐active anionic groups, Hg‐based BBUs are very competitive due to several advantages: 1) Hg 2+ cation possesses highly polarizable and deformable electron cloud, which would significantly increase the second harmonic generation (SHG) effect and birefringence; [ 12 ] 2) multiple coordination modes of Hg exist including linear, trigonal‐planar, and tetrahedral geometries, which provide opportunities to construct novel structures. Many Hg‐based IR NLO crystals have been discovered recently in both halides and chalcogenides systems with strong SHG responses and wide bandgaps ( E g ), such as Na 2 Hg 3 Ge 2 S 8 (2.2 × AGS; 2.68 eV), [ 13 ] BaHgSe 2 (1.5 × AGS; 1.56 eV), [ 14 ] SrHgGeSe 4 (4.8 × AGS; 2.42 eV), [ 15 ] CuHgPS 4 (6.5 × AGS; 2.03 eV), [ 16 ] AgHgPS 4 (5.06 × AGS, 2.63 eV), [ 17 ] Cs 2 HgI 2 Cl 2 (1 × KDP; 3.15 eV), [ 18 ] and RbHgI 3 (7 × KDP; 2.56 eV). [ 19 ] Thereby, mixed‐anion [HgQ m X n ] BBUs are expected to exist and perform well.…”

HgBrI: a possible tecton for NLO molecular materials?

“…12 At the beginning of the new century, mercury halogenides and chalcogenides received renewed attention as possible infrared nonlinear optic (NLO) materials suitable for use in the MIR spectral region because: (i) they crystallise in noncentrosymmetric space groups; (ii) show a wide IR transparency; and (iii) possess a large band gap, which can improve the laser-induced damage thresholds. 13 Three different compounds have been reported (HgBrI, Hg 2 BrI 3 and Hg 2 Br 3 I) 14 and the structural parameters of the obtained phases are quite similar. HgBrI crystallises in the noncentrosymmetric Cmc 2 1 space group, and the experimental intensity of Second Harmonic Generation (SHG) of the powder samples was 1.4 times stronger than that of potassium titanyl phosphate (KTiOPO 4 ), a common standard material in NLO devices.…”