OPTICAL-PROPERTIES OF LEAD BARIUM NIOBATE (PB1-XBAXNB2O6) CRYSTALS

PBN (Pb1-xBaxNb2O6) polycrystals have been grown by the vertical Bridg man method. Transparent, stoichiometric, striation-free single-crystal specimens of millimeter size were obtained. The ordinary and extraord inary 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 contra st to the case of SBN (Sr1-xBaxNb2O6), in which n(e) is strongly depen dent on composition. Optical transmission spectra showed PBN to be tra nsparent 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- absorpti on intensity on polarization showed that all of the O-H bonds lie eith er 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 Insti tute of Physics.