Predicting Global Minimum in Complex Beryllium Borate System for Deep-ultraviolet Functional Optical Applications

Searching for high performance materials for optical communication and laser industry in deep-ultraviolet (DUV) region has been the subject of considerable interest. Such materials by design from scratching on multi-component complex crystal systems are challenging. Here, we predict, through density function calculations and unbiased structure searching techniques, the formation of quaternary NaBeBO(3) compounds at ambient pressure. Among the four low-energy phases, the P6(3)/m structure exhibits a DUV cutoff edge of 20 nm shorter than α-BaB(2)O(4) (189 nm) – the best-known DUV birefringent material. While the P-6 structure exhibits one time second-harmonic generation efficiency of KH(2)PO(4) and possesses excellent crystal growth habit without showing any layer habit as observed in the only available DUV nonlinear optical material KBe(2)BO(3)F(2), whose layer habit limits its wide industrial applications. These NaBeBO(3) structures are promising candidates for the next generation of DUV optical materials, and the structure prediction technique will shed light on future optical materials design.