Mixed-Anion Inorganic Compounds: A Favorable Candidate for Infrared Nonlinear Optical Materials

Abstract

Infrared nonlinear optical (IR-NLO) materials are the key components in solid-state lasers for military and civilian applications. The development of IR-NLO materials remains urgent because the existing commercial materials AgGaS2 (AGS), AgGaSe2, and ZnGeP2 are limited for their own intrinsic shortcomings, for example, the lower laser damage thresholds (LDTs), the non-phase-matchable feature, and the strong two-photon absorption, respectively, exhibited in AgGaSe2 and ZnGeP2 at a conventional laser of 1 μm. Chalcogenides, halides, and iodates are known to be common sources of potential IR-NLO materials with good properties, of which the most in-depth studied is usually constructed by single anions. Recently, mixed-anion inorganic compounds are thought to be promising IR-NLO materials which can optimize comprehensive performances, especially balance the incompatibility between a large NLO coefficient and a high LDT in one material. This review focuses on the syntheses and crystal structures of mixed-anion inorganic IR-NLO materials, as well as the relationships of structure–property. Examples include four kinds of such compounds, i.e., mixed-anion chalcogenides, mixed-anion halides, mixed-anion chalcohalides, and other miscellaneous mixed-anion compounds including adducts, oxychalcogenides, oxyhalides, iodate fluorides, selenite fluorides, and halide borates. This work gives some exploring directions for novel IR-NLO materials, including how to optimize the NLO performances of the existing materials, from the inferred structure–property relationships of the potential mixed-anion inorganic NLO compounds.

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−

“…Thereby, exploring promising candidates, which can meet the double requirements at the same time of large NLO efficiencies and LDTs, may come true in chalcohalides system. Recent cases also bear out this speculation, [ 5 ] such as Ba 3 KGa 5 Se 10 Cl 2 , [ 6 ] [Rb 3 Br][Ga 3 PS 8 ], [ 7 ] Li[LiCs 2 Cl][Ga 3 S 6 ], [ 8 ] [CsBa 2 Cl][Ga 4 S 8 ], [ 9 ] and [Ba 4 Cl 2 ][ZnGa 4 S 10 ]. [ 10 ] However, these compounds are usually in the form of salt‐inclusion chalcogenides, that is, all the halogen atoms just connect with the alkali or alkaline earth metals through ionic bonds.…”

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

“…Nevertheless, these IR-NLO materials still suffer from some disadvantages (e.g., strong two-photon absorption, non-phase-matching (NPM) feature, and low laser-induced damage thresholds (LIDT)), thereby hindering their further development. In principle, for a practical and available IR-NLO material, several key conditions such as noncentrosymmetric (NCS) space group (SG), suitable birefringence (Δ n ) for phase matching (PM), large second harmonic generation response ( d ij ), high LIDT, wide transparent window, and good physicochemical properties should be achieved. − For the above-mentioned prerequisites, a large number of IR-NLO candidates have been discovered and prepared through various strategies in the past few decades. − Among them, metal chalcogenides with diamond-like (DL) structure are supposed to be the most promising IR-NLO candidates, owing to the following advantages: (i) rich asymmetric building motifs (ABMs) constructed by covalent M–Q (Q = chalcogen) bonds, including [M I Q 4 ] (M I = Li, Cu, and Ag), [M II Q 4 ] (M II = Mg, Mn, Zn, Cd, and Hg), [M III Q 4 ] (M III = B, Al, Ga, and In), [M IV Q 4 ] (M IV = Si, Ge, and Sn), and [M V Q 4 ] (M V = P, As, and Sb); (ii) intrinsic NCS crystal structures derived from the alignment of the aforementioned ABMs; (iii) wide optical transparency windows in the IR range activated by the covalent M–Q bonds; and (iv) strong polarizabilities to realize the coexistence of a large d ij and suitable Δ n . On the basis of the valence electron concentration (VEC) rule, these materials can generally be divided into two types: normal and defect DL metal chalcogenides.…”

Cd3(PO4)(TePO6): A Novel Cadmium Tellurite‐Phosphate featuring a {[TePO6]3−}∞ Chain

“…[1][2][3][4][5] These multiple anionic materials possess more moieties undertaking different functions, therefore endowing the materials balanced or improved performances, and this point has been well verified by the recent development of second-order nonlinear optical (NLO) and magnetic materials. [6][7][8] For crystalline compounds, their crystal structures are decisive for their properties. So, it is interesting to discover multiple anionic compounds with new structures.…”