Synthesis and Characterization of Mixed Carbonate and Bicarbonate Materials as Candidates for Deep-UV Applications

Abstract

The exploration of deep-ultraviolet (DUV) nonlinear optical materials remains challenging. Herein, we report three novel compounds, NaK₃Rb₂[(CO₃)(HCO₃)]₂·2H₂O (I), NaK_3.6Rb_1.4[(CO₃)(HCO₃)]₂·2H₂O (II), and NaK₅[(CO₃)(HCO₃)]₂ (III), all exhibiting cutoff edges below 200 nm. Notably, I and II represent the first non-centrosymmetric examples in this system, showing moderate SHG responses (0.2–0.3 × KDP), and encouraging further exploration of carbonate–bicarbonate DUV materials.