Additive‐Triggered Polar Polymorph Formation: β‐Sc(IO3)3, a Promising Next‐Generation Mid‐Infrared Nonlinear Optical Material. (27th July 2022) - Wu, Chao
Abstract: Noncentrosymmetric (NCS) solids have attracted interest for their potential in ferroelectric, piezoelectric, and nonlinear optical (NLO) devices, but their synthesis remains a major challenge. In this study, the additive Li2 CO3 triggers formation of an NCS precursor at an early nucleation stage, and plays a crucial role in the successful polymorphism transformation. The resultant metastable β‐Sc(IO3 )3 is a promising mid‐infrared NLO crystal, with the strongest second‐harmonic generation responses (2.2×KTiOPO4 @ 2100 nm, 16×KH2 PO4 @ 1064 nm) and the largest optical band gap (4.52 eV) for a rare‐earth iodate, as well as sufficient birefringence (Δ n =0.219 @ 546 nm) for type I phase‐matching, and wide optical transparency, which are induced by optimal alignment of the iodate anions. This study reveals the key role of additives in the growth of polar NCS solids, a discovery with implications for the strategic design of new NCS polymorphism materials with exceptional NLO properties. Abstract : The key mechanism of additives in the formation of noncentrosymmetric solids has been clarified for the first time based on a new metastable β‐Sc(IO3 )3, which exhibits excellent mid‐IR NLO properties including the strongest SHG responses and the largest band gap for a rare‐earth iodate, a sufficient birefringence, and a wide optical transparency window.