INHOMOGENEITIES AND SEGREGATION BEHAVIOR IN STRONTIUM-BARIUM NIOBATE FIBERS GROWN BY LASER-HEATED PEDESTAL GROWTH TECHNIQUE .1.

In order to study these inhomogeneities, Ce-doped and undoped strontiu m-barium niobate (SBN) fibers were grown by a laser-heated pedestal gr owth (LHPG) technique in various Ce:SrxBa1-xNb2O6 compositions along b oth c [001] and a [100] crystallographic axes. Specific optical inhomo geneities distributed in a radial manner (core effects) are observed i n such crystals. Two-dimensional scanning electron microprobe analysis (SEPMA) indicated Ba enrichment and Sr decrease in the cores. An appr oximate control segregation coefficient ('k(oA)) was introduced to cha racterize the segregation in the fibers. For different cations 'k(oSR) = 0.98, 'k(oBa) = 1.04 and 'k(oNb) = 0.99 were obtained which both de termine and demonstrate the complexity of the inhomogeneities in the c ore in the radial direction.