Sr₆(Li₂Cd)A₄S₁₆ (A = Ge, Sn): How to Go beyond the Band Gap Limitation via Site-Specific Modification

Abstract

Band gap tuning is at the core of current optical and electronic device applications, the wide-band-gap chalcogenides are especially challenging and highly desired in many fields, such as nonlinear optical materials. On the basis of our in-depth investigation on the complicated cubic AII 6(BI 2CII)­DIV 4S16 family, we reveal that the structural complexity causes the band gap tuning to be determined by multiple factors, in which a “bucket effect” is uncovered. Guided by such a bucket effect strategy, we rationally synthesized two new members, Sr6(Li2Cd)­A4S16 (A = Ge (1; a = 13.916 Å), Sn (2; a = 14.237 Å), via a site-specific substitution. 1 exhibits the widest band gap (3.8 eV) in this family known to date. Benefiting from their wide band gaps, 1 and 2 exhibit excellent laser irradiation duration capability, with laser-induced damage thresholds (LIDTs) of 55.5 and 44.4 MW/cm2 at a 1.064 μm incident laser, which are 21 and 17 times higher than that of the benchmark AgGaS2 (2.69 MW/cm2). Especially, the LIDT of 1 is the highest known to date among the cubic AII 6BI 2CIIDIV 4S16 family. Our insight into the band gap tuning in a complex system should shed useful light on the future design of functional materials and band gap engineering.

SrZnGeS4: A Dual‐Waveband Nonlinear Optical Material with a Transparency Spanning UV/Vis and Far‐IR Spectral Regions

“…When there is a significant difference between the E g s of the binaries M II Q and M IV Q 2 (Δ E g >0.5 eV), the one carries the lower E g acts as the shortest board, and eventually determines the E g of the quaternary. A similar “bucket effect” is widely found for the complex cubic A II 6 (B I 2 C II )D IV 4 S 16 family [15] …”

EuHgGeSe4 and EuHgSnS4: Two Quaternary Eu-Based Infrared Nonlinear Optical Materials with Strong Second-Harmonic-Generation Responses

“…Nonlinear optical (NLO) crystals are one type of crucial materials in all-solid-state lasers with the properties of frequency conversion and broadening the output spectral range and hence have attracted broad attention in recent years. , Generally, researchers classify NLO materials into several subgroups, including infrared (IR), ultraviolet–visible (UV–vis), and deep ultraviolet (DUV), according to the serving regions. In terms of IR NLO materials, metal chalcogenides are the most promising candidates due to their advantages in diverse noncentrosymmetric (NCS) structures, wide IR transmittance ranges, strong NLO responses, and favorable single-crystal growth habits, − as shown by the commercial IR NLO materials AgGaS 2 (AGS) and AgGaSe 2 (AGSe). , Because of the increasing demands in laser technology and the disadvantages of the current commercial IR NLO materials (two-photon absorption of a 1 μm pumping laser for AGSe and low laser-induced damage threshold (LIDT) for AGS and AGSe), some metal chalcogenides with large band gaps, high SHG coefficients ( d ij ), large LIDT, phase matchability, and favorable single-crystal growth habits, such as BaGa 4 S 7 , BaGa 4 Se 7 , , BaGa 2 GeS 6 , and BaGa 2 GeSe 6 , have been regarded as new-generation IR NLO materials. However, the research involving these materials has been focused in laboratories, since they are usually obtained by small-scale reactions.…”

Ba6(CuxZy)Sn4S16 (Z = Mg, Mn, Zn, Cd, In, Bi, Sn): High Chemical Flexibility Resulting in Good Nonlinear-Optical Properties

“…15 The absence of attractors capping Sn atoms also confirmed that the oxidation state of Sn is 4+. 15 The 2.34 Å Sn−S interactions show the strongest 50 There are many factors contributing to the LDT of crystalline solids. The LDT has two parts: dielectric and thermal LDT.…”

“…), trivalent M 3+ (Al, In, Ga, etc. ), tetravalent M 4+ (Si, Ge, Sn), and pentavalent M 5+ (Sb); Ch = S, Se], which have demonstrated an excellent balance of NLO properties originating from their chemical flexibility. − Recently, another system, II 6 I 4 V 4 Ch 16 (II = Sr, Ba; I = Li, Cu, Ag; IV = Ge, Sn; Ch = S, Se), has been heavily studied because of their emerging NLO properties and the demonstration of their excellent chemical flexibility. − In this work, we discovered another seven compounds belonging to the II 6 I 4 V 4 Ch 16 (II = Sr, Ba; I = Li, Cu, Ag; IV = Ge, Sn; Ch = S, Se) family. The chemical flexibility of the II 6 I 4 V 4 Ch 16 (II = Sr, Ba; I = Li, Cu, Ag; IV = Ge, Sn; Ch = S, Se) family is further expanded on with the discovery of trivalent dopants for the first time.…”