Noncentrosymmetric cubic RbBSi2O6 polymorph with deep ultraviolet cut-off edge

By the introduction of Rb + with large ionic radius and rigid SiO 4 unit into borate , a noncentrosymmetric crystal, RbBSi 2 O 6 polymorph has been obtained. Its structure was determined by single crystal X-ray diffraction technique , and it can be described as a three dimensional (3D) framework constructed by the Si/BO 4 tetrahedra via corner-sharing O atoms, the Rb atoms reside in the tunnels and large cavities of the 3D framework. In addition, the optical properties of RbBSi 2 O 6 and CsBSi 2 O 6 , including IR spectra , UV–Vis–NIR diffuse reflectance spectra, have been reported in this work. Both RbBSi 2 O 6 and CsBSi 2 O 6 reveal short deep ultraviolet (UV) cutoff edges (below 180 nm and 185 nm, respectively), so they may have potential application in deep UV fields. Furthermore, the first-principle theoretical studies on band structure and density of states have also been performed for RbBSi 2 O 6 .