NaZnCO₃(OH): A High-Performance Carbonate Ultraviolet Nonlinear Optical Crystal Derived from KBe₂BO₃F₂

Currently, to obtain new ultraviolet (UV) nonlinear optical (NLO) materials with large second-harmonic generation (SHG) response and short SHG phase-matching cutoff wavelength (λ_PM) is still very challenging. Herein, through evolving the KBe₂BO₃F₂ (KBBF) structure to a carbonate system, a novel hydroxycarbonate UV NLO crystal, NaZnCO₃(OH), was successfully synthesized. It not only possessed the typical structural characteristics of KBBF but also enhanced the bonding force between functional layers. Remarkably, in this crystal, the rare coexistence of a very large SHG response of 5.2 × KH₂PO₄ (KDP, @1064 nm) and short type-I SHG λ_PM of 201 nm had been achieved, indicating that it was a promising UV NLO crystal. This work showed the great significance of KBBF structure evolution and provided new opportunity to design UV NLO materials with good performance.