Ba3Ca4(BO3)3(SiO4)Cl: a new non-centrosymmetric complex alkaline-earth metal borosilicate chloride with a deep-ultraviolet cut-off edge

Abstract

A new complex alkaline-earth metal borosilicate chloride Ba₃Ca₄(BO₃)₃(SiO₄)Cl has been successfully synthesized by the high-temperature solution method. It crystallizes in the space group P6₃mc (no. 186) of the hexagonal system. Its structure features a ³_∞[Ca₄(BO₃)₃(SiO₄)] framework formed by interconnected ¹_∞[Ca₄(BO₃)₃(SiO₄)O₉] chains with large octagonal star-like channels, in which the ¹_∞[Ba₃Cl] chains are located. The second harmonic generation (SHG) measurement shows that Ba₃Ca₄(BO₃)₃(SiO₄)Cl has an SHG of about 0.6 times that of KH₂PO₄ and it is phase matchable. In addition, it melts congruently and exhibits a wide transparent range with the UV cut-off edge below 190 nm. All the above indicates that Ba₃Ca₄(BO₃)₃(SiO₄)Cl could be regarded as a potential ultraviolet nonlinear optical material.