Topology-Guided Discovery of BaIn 2 Si 7 P 12 : A Quaternary Diamond-like Framework Phosphide with Giant Second-Harmonic Generation and High Laser-Induced Damage Threshold

Achieving both a large second-order nonlinear optical (NLO) coefficient and high laser-induced damage threshold (LIDT) is a vital but addressable challenge in advanced infrared (IR) NLO material design. Herein, we report the rational design and synthesis of the first quaternary diamond-like framework (DLF) phosphide, BaIn2Si7P12, through a topological modification and mathematical modeling combined strategy. The compound crystallizes in the non-centrosymmetric R3 space group and inherits the structural advantages of DLFs (oriented tetrahedral units) and phosphides (inherent high LIDT), exhibiting a strong NLO response (6 × AGS, surpassing most reported DLF compounds) and a high LIDT (8.3 × AGS). Density functional theory calculations reveal that the enhanced NLO response stems from the synergistic effects of high hyperpolarizability in SiP4 and InP4 tetrahedra and their orientated arrangement within the DLF. The results demonstrate that DLF phosphides represent a promising system for developing high-performance IR NLO materials and illustrating the effectiveness of this strategy.