Mn doped 0.95Na(0.5)Bi(0.5)TiO(3)-0.05BaTiO(3) (NBBT5) single crystal was grown by the top-seed solution growth (TSSG) method. After different annealing processes, the temperature dependence of conductivity and Arrhenius relation were used to calculate the conduction activation energies and analyze the defect structure in Mn:NBBT5 crystal. Two different activation energies in different temperature regions were observed, corresponding to different conduction mechanisms. It should be noted that a large electrostrain up to 1% was obtained after being annealed in oxygen atmosphere, due to the "aged effect". (C) 2010 Elsevier B.V. All rights reserved.