A Lanthanum Ammonium Sulfate Double Salt with a Strong SHG Response and Wide Deep-UV Transparency

The targeted synthesis of deep-ultraviolet (deep-UV) nonlinear optical (NLO) materials, especially those with non-pi-conjugated sulfates, has experienced considerable difficulties due to the need to reconcile the oft-competing requirements for deep-UV transparency and strong second-harmonic generation (SHG). We report herein the designed synthesis of the first rare-earth metal-based deep-UV sulfate La(NH4)(SO4)(2) by a double-salt strategy involving introduction of complementary cations, together with optical studies that reveal a short-wavelength deep-UV absorption edge (below 190 nm) and the strongest SHG response among deep-UV NLO sulfates (2.4xKDP). Theoretical calculations and crystal structure analysis suggest that the excellent balance between SHG response and deep-UV transparency can be attributed to a synergistic interaction of the hetero-cations La3+ and [NH4](+), which optimize alignment of the [SO4] tetrahedra and highly polarizable [LaO8] polyhedra.

Automated summary

This study reports the targeted synthesis of deep-UV non-linear optical material La(NH4)(SO4)(2) using a double-salt strategy. Optical studies show that this material exhibits a short-wavelength deep-UV absorption edge and the strongest SHG response among deep-UV NLO sulfates, attributed to the synergistic interaction of La3+ and [NH4]+.