Bulk single crystals were grown by using a modified Czochralski method, using Na2O and NaF as solvents. It was found that the formation of twins (electric type) or cellular sub-structures at various scales were typical growth features. It was suggested that their formation was governed by changes in the composition and structure of the double-electric layer at the growing interface. In the case of Z-axis crystals, only micro-twin structures were revealed. Their number and location were governed by the composition of the solvent. Cellular growth of these crystals at certain stages was the result of the impossibility of formation of an antipolar structure (macro-twin) under conditions of increasing charge density in the double-electric layer. In the case of Y- and X-axis crystals, the conditions of formation of 1, 3, 5 etc. macro-twin boundaries and therefore non-cellular growth were always satisfied.

Some Concepts Concerning Twinning and Cellular Growth of Bulk Barium Metaborate Crystals. V.I.Tyurikov, E.G.Tsvetkov, V.D.Antsygin, G.G.Khranenko, E.G.Samoilova: Optical Materials, 2000, 14[4], 313-20