Run Ye,Bin-Wen Liu,Xiao-Ming Jiang,Jian Lu,Hui-Yi Zeng,Guo-Cong Guo
Exploration of a new nonlinear optical (NLO)-active functional motif is important in the rational design of promising infrared (IR) NLO materials. Compared with typical tetrahedral MQ4 (M = IIB, III, IV metals; Q = S, Se) motifs, MQ3 (M = As, Sb) pyramids favor high second-harmonic generation (SHG) efficiency while frequently hindering phase matching (PM) because of excessively large optical anisotropy. The surfactant–thermal method was first adopted to achieve PM in MQ3-containing systems and synthesize mixed covalent–ionic IR NLO materials. Two new thioarsenates of AMnAs3S6 (A = Cs, Rb) exhibiting strong PM SHG efficiencies comparable to commercial AGS and laser-induced damage thresholds of one order higher than AGS were obtained. The [As3S6]3– unit in their structures is an unprecedented NLO-active functional motif, which can be useful in designing new IR NLO compounds with large SHG efficiency. In addition, the surfactant–thermal method provides a new general strategy for synthesizing new IR NLO materials.
Infrared (IR) nonlinear optical (NLO) material with a concurrently wide band gap and significant NLO coefficient in a single crystal is an incompatible but addressable challenge. Hence, for the first time, the AgGaS 2 structure evolved into an Ag-based sulfide system integrating dual s -block elements, guiding the discovery of two NLO crystals named AMgAgGa 6 S 11 (A = K, 1 ; Rb, 2 ). Structurally, title phases possess a novel NLO functional motif [AgGa 6 S 17 ] assembled by two C 2 -type supertetrahedra through a shared [AgS 4 ] tetrahedron, in which the electropositive cations A + and Mg 2+ are embedded. Thus, compounds 1 and 2 display emulative band gaps (3.15 and 3.25 eV, exceeding that of 2.65 eV in AgGaS 2 ) toward optimizing the laser-induced damage thresholds (3.1 and 3.2 × AgGaS 2 @1064 nm). Remarkably, the noncentrosymmetric phases 1 and 2 exhibit moderate second-harmonic generation (SHG) responses (0.6 and 0.7 × AgGaS 2 @1910 nm), the greater-than-commercial half of the AgGaS 2 . To the best of our current knowledge, an experimental birefringence of 1 and 2 (0.029 and 0.027, @546 nm) is first observed in quinary ordered chalcogenides , indicating that samples 1 and 2 meet phase-matching conditions at the incident laser of 1910 nm. All these observations demonstrate that crystals 1 and 2 can become prospective NLO materials. This research will pave the way for discovering excellent IR NLO crystals with wide band gaps and impressive NLO coefficients by incorporating multiple strong electropositive elements into chalcogenides .
A growing need for high-energy-density lithium metal batteries appeal for utilize ultrathin (≤50 μm) free-standing Li metal anodes . However, challenges such as the formation of an unstable solid electrolyte interphase and the lithium dendrites growth have led to poor cycling performance and safety concerns, limiting the commercial viability of thin lithium metal anodes. This work introduces a facile approach by designing and fabricating an ultrathin Li-In alloy anode through in-situ vacuum melting and codirectional continuous rolling. The rolled ultrathin Li-In anode achieves the induction of uniform epitaxial electrodeposition of Li(110), which is attributed to the lithiophility of the densely distributed In₃Li₁₃ alloy phase and the coherent heterogeneous relationship between textured In₃Li₁₃(311) and Li(110).The symmetrical cell assembled by 50 μm Li-In alloy anode exhibits a prolonged lifespan for 1800 h under the conditions of 1 mA cm -2 and 3 mAh cm -2 . Meanwhile, the LiFePO 4 ||Li-In (50 μm) full cell achieves sTable 450 cycles with a retention of 90.3 % at 2 C (1 C = 170 mA g -1 ). This work paves the path for the practical ultrathin Li anode for commercializing the lithium metal batteries .
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