Large tetragonal phase (La,Sr)(Al,Ta)O-3 (LSAT) crystals used as substrates for growing functional thin-film materials were successfully grown by the Czochralski method using [0 0 1] LaAlO3 rod as seed. The crystal phase was determined by the method of powder X-ray diffraction analysis and the transmission spectrum indicates that the absorption edge of the crystal is at 270 nm while no apparent absorption peaks were found. Through the technique of environmental scanning electron microscopy and synchrotron radiation white-beam topography, the surface topography and defects were characterized, and clear and stable images of twins, micro-cracks, inclusions, grain boundaries, dislocation etch pits, and growth striations in the as-grown LSAT crystals were obtained. (C) 2002 Elsevier Science B.V. All rights reserved.