Crystal and Electronic Structures and Linear Optics of Strontium Pyroborate

The compound Sr2B2O5has been synthesized by high temperature solution reaction. It crystallizes in the monoclinic space groupP21/cwith cell dimensionsa=7.719(4),b=5.341(1),c=11.873(2)?,=92.71(2)°,V=488.9(3) ?3, andZ=4,Dcalc=3.76 g/cm3. The structure comprises SrO7and SrO6polyhedra and B2O5groups. The electronic structure has been calculated by the INDO/S method for this compound, and the dynamic refractive indices have been obtained in terms of INDO/SCI following combination with the sum-over-states method. The calculated energy gap is 4.26 eV between the upper valence band and lower conduction band, and the calculated average refractive index is 1.791 at a wavelength of 1.065 m. The charge transfers from O2-anion orbitals to Sr2+cation orbitals make the significant contributions to linear polarizability in terms of analyses of atomic state density contributing to the valence and conduction bands.