The dielectric properties and phase transition of Sm3+-doped BaZr0.2Ti0.8O3 (BZT20) ceramics were investigated. Room temperature X-ray diffraction study suggested that the compositions had single-phase cubic symmetry. Microstructure studies showed that the grain size decreased and that the Sm2O3 amount markedly affected the dielectric properties of BZT20. A dielectric constant of 5700 at 0.2 mol% Sm2O3 and a dissipation factor of only 0.0011 at 2 mol% Sm2O3 were observed, indicating that BZT20 had significant potential applications. Moreover, the dielectric constant, dissipation factor, phase-transition temperature, and maximum dielectric constant increased with increased Sm2O3 amount at <= 0.2 mol% Sm2O3 but decreased with increased Sm2O3 amount at >0.2 mol% Sm2O3. (C) 2013 Elsevier Ltd. All rights reserved.