Ba4(BO3)3(SiO4)•Ba3X(X = Cl, Br): new salt-inclusion borosilicate halides as potential deep UV nonlinear optical materials

Based on the combination of two different anionic groups (SiO4 and BO3) and the utility of a XBa6 (X = Cl, Br) polar template, two new salt-inclusion compounds, Ba-4(BO3)(3)(SiO4)center dot Ba3X (X = Cl, Br) have been successfully synthesized by the high-temperature solution method for the first time. They are isostructural and their structures feature the (infinity) (3)[Ba-4(BO3)(3)(SiO4)] framework with 1D channels along the c axis, in which resided the polar (infinity) (1)[Ba3X] chains. It is worth noting that they are the first alkaline-earth metal borosilicate halides to be used as nonlinear optical (NLO) materials. The second harmonic generation (SHG) measurements show that they have SHG responses similar to that of KH2PO4 (KDP) and are type-I phase-matchable. In addition, they melt congruently and exhibit a wide transparent region with the UV cut-off edge below 190 nm. These properties make Ba-4(BO3)(3)(SiO4)center dot Ba3X potential deep UV NLO materials.