Crack-free and transparent Zn2TiO4 single crystals of 4-6 mm in diameter and 30 mm in length have been grown by the optical floating zone method The powder X-ray diffraction (XRD) results show that the as-grown crystals have the spmel-type Zn2TiO4 structure XRD2 measurements on Zn2TiO4 waters cut perpendicular to the growth direction display only one peak at 42 7 which indicates that the Zn2TiO4 single crystals grow along the < 4 0 0 > direction (a-axis) The formation of bubble inclusions was effectively suppressed by lowering rotation rate Transmission polarized-light microscopy results showed that as-grown crystals were free of low angle grain boundaries (C) 2010 Elsevier B V All rights reserved