Balanced IR Nonlinear Optical Performance Achieved by Cation–Anion Module Cosubstitution in V-Based Salt-Inclusion Oxychalcogenides

High Resolution Image Download MS PowerPoint Slide Oxychalcogenides have become notable contenders for infrared nonlinear optical (IR NLO) applications because of their diverse heteroanionic functional motifs. However, while the main group elements are well-explored for these motifs, transition elements have been less studied and lack high-performance materials. To address this gap, we investigated a series of noncentrosymmetric [Ba 4 (Ba 6 S)][(VO x S 4– x ) 6 ] (space group: P 6 3 ), the first V-based salt-inclusion oxychalcogenides demonstrating phase-matched IR-NLO properties. We achieved this by cation–anion module cosubstitution in the centrosymmetric structure of [Ba 4 (Ba 6 Cl 2 )][(VO 4 ) 6 ] (space group: P 6 3 / m ). The novel [Ba 4 (Ba 6 S)][(VO x S 4– x ) 6 ] features isolated heteroanionic [VO x S 4– x ] 3– units, charge-balanced Ba 2+ cations, and a one-dimensional cationic chain of [Ba 6 S] 10+ octahedral units. Moreover, [Ba 4 (Ba 6 S)][(VO 3 S) 6 ] exhibits notable properties including a high second-harmonic-generation intensity (1.33 × AgGaS 2 @2900 nm), a substantial laser-induced damage threshold (7.65 × AgGaS 2 ), a broad IR cutoff edge (up to 11.2 μm), and significant birefringence for phase matching (Δ n = 0.073@2900 nm). Structural analysis and DFT calculations demonstrate that the configuration of the [VO 3 S] 3– units enhances NLO properties and increases structural anisotropy. Our findings suggest that V-based salt-inclusion oxychalcogenides are a promising class for IR-NLO applications and highlight cation–anion module cosubstitution as an effective approach for creating high-performance heteroanionic NLO crystals.