Li3B8O13X (X = Cl and Br): Two New Noncentrosymmetric Crystals with Large Birefringence Induced by BO3 Units

Enthusiasm for the exploration of nonlinear alkali metal borates remains high. Focusing on the Li-B-O-X (X = Cl and Br) system, two examples of noncentrosymmetric borates, Li3B8O13Cl and Li3B8O13Br, were obtained using a high -temperature solution method under vacuum conditions. Structurally, the Li3B8O13X crystals exhibit two independent alternately arranged three-dimensional B-O network structures formed by the basic building block unit B8O16. The performance measurements demonstrate their short ultraviolet cutoff edges. The theoretical calculation indicates that the BO3 units dominate the contribution to their large optical anisotropy with the birefringence, 0.094 and 0.088@1064 nm for Li3B8O13Cl and Li3B8O13Br, respectively.

Automated summary

Enthusiasm for the exploration of nonlinear alkali metal borates remains high. In this study, two noncentrosymmetric borates, Li3B8O13Cl and Li3B8O13Br, were successfully obtained using a high-temperature solution method under vacuum conditions. The crystal structures of Li3B8O13X exhibit two independent alternately arranged three-dimensional B-O network structures. Performance measurements show that both materials have short ultraviolet cutoff edges. Theoretical calculation reveals that the BO3 units contribute to their large optical anisotropy with specific birefringence values at 1064 nm.