Stepwise Li Substitution Induced Structure Evolution and Improved Nonlinear Optical Performance for Diamond-like Sulfides

Abstract

One of the key scientific issues for exploration of novel infrared nonlinear optical (NLO) crystals is to obtain ones with good hybrid NLO behaviors. Herein, we report four diamond-like Ag-based sulfides via stepwise Li substitution of Ag in Ag 2 ZnSnS 4 , including Ag 2 ZnSnS 4 (1), (Li 1.22 Ag 0.78 )ZnSnS 4 (2), (Li 1.58 Ag 0.42 )ZnSnS 4 (3), and Li 2 ZnSnS 4 (4). With the increase of Li content, the sulfide's noncentrosymmetric crystal structure changes from tetragonal I42m for 1, to orthorhombic Pmn2 1 for 2 and 3, and to monoclinic Pn for 4. Accordingly, their NLO responses are improved along with the increase of Li content, viz. from non-NLO-active for 1, to non-phase-matchable for 2 and 3, and to phase-matchable for 4. Their optical band gaps also increase regularly. The relationship between their chemical compositions, crystal structures, and NLO activities is investigated by means of chemical structural analysis and theoretical calculation. This work offers a new systematic case for designing promising NLO-active compounds via rarely adopted cation's stepwise partial substitution and understanding the chemical composition−structure−NLO property relationship.

(Na0.74Ag1.26)BaSnS4: A New AgGaS2‐Type Nonlinear Optical Sulfide with a Wide Band Gap and High Laser Induced Damage Threshold

“…Moreover, the NLO data of A I 2 B II C IV D VI 4 family (A = Ag, Cu, Li, Na,; B = Sr, Ba, Zn, Cd, Hg; C = Si, Ge, Sn; D = S, Se) are summarized in Table S1. The NLO response of (Na 0.74 Ag 1.26 )BaSnS 4 is comparable to those of Ag 2 BaSnSe 4 (0.1–0.2 × AGS), [30] Na 2 BaGeS 4 (0.3 × AGS), [26] and Li 2 ZnSnS 4 (0.3 × AGS) [31] . However, it is better to further improve the NLO response via some strategies.…”

Alkali metal partial substitution-induced improved second-harmonic generation and enhanced laser-induced damage threshold for Ag-based sulfides

“…The optical property calculation details can be referred to in our previous studies. 40,41 In addition, the calculation for crystal orbital Hamilton population (COHP) was implemented on tight-binding linear muffin-tin orbital atomic sphere approximation (TB-LMTO-ASA) software to judge the type of Na-S bonds. 42…”

“…24 The enhanced NLO responses from 0 to 1 and 2 illustrate that alkali metal partial substitution of Ag-based sulfides can induce improved NLO properties effectively. 40,41 The specific reasons for the improved NLO behavior will be discussed in detail in the following Theoretical calculation section.…”

Cubic Crystal Structure Formation and Optical Properties within the Ag–BII–MIV–X (BII = Sr, Pb; MIV = Si, Ge, Sn; X = S, Se) Family of Semiconductors

“…Quaternary chalcogenide semiconductors represent a rich source of promising materials for applications such as photovoltaics (PV), − photoelectrochemical cells, , thermoelectric (TE) generators, − and infrared (IR) nonlinear-optical (NLO) crystals. ,− This broad materials set has attracted interest connected to a variety of applicationse.g., wide-band gap compounds such as Li 2 CdGeS 4 and Na 2 ZnGe 2 S 6 may find use in optics and electronics, while narrower band gap Ag 2 BaSnSe 4 and Cu 2 ZnSnSe 4 can be employed for TE systems . The multinary nature of these chalcogenides allows for broad tunability of the pertinent properties (e.g., band gap, defect properties, and carrier concentration) by changing the elemental components. ,− Beyond the specific composition, the crystal structure of any individual compound can determine or limit the tunability and range of the optical, electronic, and thermal properties. For example, various crystal structures of quaternary chalcogenides can be amenable to property tuning by element substitution, as was seen in recent alloying studies of Cu 2 BaSn­(S,Se) 4 and Cu 2 Ba­(Ge,Sn)­Se 4 by some of the current authors. , …”