Novel antimony-based mixed halides exhibiting an excellent SHG response and a broad transmission range

Abstract

In this study, we successfully synthesized two novel non-centrosymmetric (NCS) antimony halide compounds, RbSbF₃Cl and Rb₃Sb₄F₁₄Cl. These compounds were formed by combining Sb³⁺ cations, which possess stereochemically active lone pairs (SCALP), with halogen atoms (fluorine and chlorine). The introduction of mixed halogen atoms enables Sb atoms to adopt multiple coordination modes, which in turn promotes the development of both compounds towards NCS structures. Notably, Rb₃Sb₄F₁₄Cl demonstrated a large second harmonic generation (SHG) response, approximately three times greater than that of KH₂PO₄ (KDP), along with a wide transparency range from 0.27 to 13.3 μm and a high laser damage threshold (LDT) of 223 MW cm⁻². These exceptional properties indicate that Rb₃Sb₄F₁₄Cl is a highly promising nonlinear optical (NLO) crystal with excellent overall performance, making it suitable for potential applications spanning the short-wave ultraviolet (UV) to mid-infrared (IR) spectral regions. In contrast, RbSbF₃Cl exhibits a large birefringence of 0.31 at 546 nm as a uniaxial crystal, suggesting its practicability as a birefringent material.