The characteristics of reduced-twin crystals that had been grown by using a high-pressure melting method were studied. The crystals were grown by using the seeded vertical Bridgman method, and gradient freezing. Monocrystals (2.54cm) with twin-reduced portions, and an average etch-pit density of 2 x 105/cm2, were successfully grown by using the seeded Bridgman method. Multi-twin patterns, that were typical of melt-grown boules, were not revealed by optical microscopy, using crossed polaroids, or transmission X-ray topography. The crystallinity of the as-grown crystals was characterized by means of X-ray rocking curve analysis, using a double-crystal arrangement. A full-width at half-maximum of 24arcsec was detected.

T.Fukuda, K.Umetsu, P.Rudolph, H.J.Koh, S.Iida, H.Uchiki, N.Tsuboi: Journal of Crystal Growth, 1996, 161, 45-50