Growth, optical transmission and X-ray photoemission studies of BaB2O4 single crystals

Beta barium borate (beta-BBO) crystals have been grown by the top seeded so lution growth technique (TSSG) using Na2O as a flux. The crystals exhibited high transparency and the absence of inclusions and found to have sodium c ontamination in the range 150 to 230 p.p.m. The effect of this contaminatio n on some crystal properties of interest has been investigated. The presenc e of impurities causes optical absorption below 550 nm in BBO crystals of b oth alpha and beta-phases. X-ray photo emission spectroscopy (XPS) measurem ents performed on these crystals show that sodium gives rise to a measurabl e shift in the binding energies of the constituent ions. Further, the resul ts show that Na+ ions enter into the lattice substitutionally and provide c harge trapping sites close to the band edge.