Designing Silicates as Deep-UV Nonlinear Optical (NLO) Materials using Edge-Sharing Tetrahedra.

Discovering new deep-ultraviolet (DUV) nonlinear optical (NLO) materials is currently a great challenge. The reported DUV NLO materials are almost exclusively borates or phosphates. Silicates-the largest constituent of the earth's crust-are excluded owing to their weak second harmonic generation (SHG) response. We report a silicate, Li2 BaSiO4 , with edge-sharing LiO4 -SiO4 tetrahedra that achieves the balance between a short UV absorption edge, below 190 nm, and a large SHG response, 2.8×KDP. The SHG intensity is the largest for silicates without second-order Jahn-Teller cations, and exceeds that of non-isomorphic Li2 SrSiO4 by more than an order of magnitude. As such Li2 BaSiO4 may be seen as a promising DUV-UV NLO material. This research indicates that edge-sharing tetrahedra is a new design parameter for discovering new DUV NLO materials.