A mixed alkali-metal nonlinear optical (NLO) dihydro-cyanurate crystal Rb3Na(H2C3N3O3)4·3H2O has been synthesized via the hydrothermal method. Its calculated birefringence is about 0.368, which is very large, its ultraviolet (UV) cutoff edge is down to 230 nm, and the powder second harmonic generation (SHG) intensity is about 0.2 × KDP. In addition, a first-principles investigation of the electronic properties on Rb3Na(H2C3N3O3)4·3H2O was carried out. The calculated band gap and SHG coefficient values agree well with the experimental ones. These results suggest that it could be applied as a UV birefringent material.

The material with a large birefringence is needed for the optical system, and borate is a good choice for excellent birefringent material. Herein, we report two borates BaMⅣ(BO3)2 (MⅣ =...

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