ew compositions for perovskite-type oxides (RE, Sr)(Al, Ta)O-3 (RE = La, Nd) were investigated from solid-state reactions and grown by Czochralski method as substrates for GaN epitaxial growth. These compounds crystallize in a cubic system. The lattice mismatch with GaN is in the range of 1.24-1.70%. The linear expansion coefficients are around 10 x 10(-6) K-1. Hydride vapor phase epitaxy growth of GaN was performed on (La, Sr)(Al, Ta)O-3 substrates. Free-standing GaN wafers similar to300 mum thick were obtained. (C) 2002 Elsevier Science B.V. All rights reserved.