Optical properties of lead barium niobate (Pb1-xBaxNb2O6) crystals

PBN (Pb1-xBaxNb2O6) polycrystals have been grown by the vertical Bridgman method. Transparent, stoichiometric, striation-free single-crystal specimens of millimeter size were obtained. The ordinary and extraordinary refractive indices, n(o) and n(e), of crystals with compositions Pb0.50Ba0.50Nb2O6 and Pb0.57Ba0.43Nb2O6 were measured by the minimum deviation method using optically polished prisms. Neither n(o) nor n(e) was found to be strongly dependent on crystal composition, in contrast to the case of SBN (Sr1-xBaxNb2O6), in which n(e) is strongly dependent on composition. Optical transmission spectra showed PBN to be transparent in the range from 0.4 to 5 mu m except for the OH- absorption bands around 2.87 mu m. The dependence of the integrated OH- absorption intensity on polarization showed that all of the O-H bonds lie either in the a-b plane or along the c axis, with a greater density of O-H bonds in the a-b plane than along the c axis. (C) 1997 American Institute of Physics.