Electronic and Optical Properties of Strontium Barium Niobate Single Crystals

Abstract

Abstract Electronic structure of Sr x Ba1- x Nb2O6 crystals in the energy range involving the valence and conduction bands has been studied theoretically and experimentally using the DFT-based ab initio VASP code and the spectroscopic ellipsometry method with synchrotron radiation. The Sr0.61Ba0.39Nb2O6 sample of the congruently melting composition is characterized by the greatest difference of the experimental dielectric function ϵ(E) compared to the non congruently melting compositions of Sr x Ba1- x Nb2O6 (x = 0.40, 0.55, 0.65, 0.75). Electronic band structures of Sr0.60Ba0.40Nb2O6 and LiNbO3 crystals in the energy range of 6–8 eV and the corresponding dielectric functions ϵ(E) in the photon energy range of 3–10 eV have been found to be similar, what is caused by similar octahedral NbO6 complexes in the crystals. Keywords: SBN crystalelectronic structureoptical properties Acknowledgment This work was supported by the European Community Research Infrastructure Action under FP7 (EC Grant Agreement no. 226716–ELISA) in the frame of the BESSY-projects 10.1.91004 and 10.2.100107. We also want to thank the Helmholtz-Zentrum Berlin (BESSY II) for help and support. Calculations of band structure and related properties of crystals were done partly at ICM of Warsaw University in frame of the project G26-3.