Designing A New Infrared Nonlinear Optical Material, β‐BaGa₂Se₄ Inspired by the Phase Transition of the BaB₂O₄ (BBO) Crystal

Abstract

Infrared nonlinear optical (IR NLO) crystals play as ignificant role in the development of IR laser technology. But rationally designing anew IR NLO crystal remains ahuge challenge because of the unpredictability of inorganic structures.H erein, inspired by phase transformation of the famous BaB 2 O 4 (BBO) crystal, atemperature-induced centrosymmetric (CS) to noncentrosymmetric (NCS) transformation approach is employed in CS BaGa 2 Se 4 to uncover an ew NCS ternary chalcogenide, b-BaGa 2 Se 4 whichc an exhibit the wellbalanced NLO properties,including moderate phase-matching SHG response ( % 0.6 AgGaS 2 ), high LDT (10 AgGaS 2 ), and large birefringence (Dn = 0.18 in the visible region). Therefore, b-BaGa 2 Se 4 will be ap romising IR NLO crystal. The analysis for the structure-property relationship shows that the excellent NLO properties of b-BaGa 2 Se 4 mainly originate from edge-sharing GaSe 4 tetrahedral chains,w hicha re different from B 3 O 6 groups in b-BBO and respect an ew direction for the design of IR NLO crystals.S o, we believe that the current researchp rovides not only an ew IR NLO crystal but also some insights for the design of new IR NLO crystals.

An Unprecedented Crystalline La(II)-Chalcogenide LaMg6Ga6S16 with Multifunctional Properties

“…4d and Table S4). 43,44,45 The birefringence of LaMg 6 Ga 6 S 16 was also measured on a plate-shaped crystal. It indicates that the birefringence of LaMg 6 Ga 6 S 16 at visible light is 0.041 (Figure S6 and Figure S7).…”

“…Based on the Michal-Levy chart, its retardation (R value) is about 920 nm. According to the equation R = Δn×d (where R, Δn, and d represent retardation, birefringence, and thickness, respectively), 45,47 the birefringence of LaMg 6 Ga 6 S 16 can be calculated.…”

Wide band gap selenide infrared nonlinear optical materials AIIMg6Ga6Se16 with strong SHG responses and high laser-induced damage thresholds

“…23,24 However, for most selenides, their band gaps are narrow due to the presence of outer electrons on the 3d, 4s, 4p orbits in the Se atom. 25,26…”

New ultraviolet transparent rare-earth borates with enhanced birefringence induced by cation chemical substitution

“…26,27 Generally, introducing strongly distorted basic building units (BBUs) into the structure is conducive to increase the birefringence of materials. 28–30 These BBUs typically consist of the polyhedra with cations susceptible to second-order Jahn–taller (SOJT) effects, including d 0 transition metals (Nb 5+ , Mo 6+ , W 6+ , etc .) and stereochemically active lone pair (SCALP) cations (Pb 2+ , Sn 2+ , Sb 3+ , etc .).…”