Dielectric properties and relaxation behavior of Sm substituted SrTiO_3 ceramics

摘要

Sr_(1-1.5x)Sm_xTiO_3 (x = 0-0.025) ceramics were fabricated by the conventional solid-state reaction method. Experimental results show that all ceramics are pure cubic perovskite structure, and the lattice parameters and average grain sizes of the ceramics decrease with the Sm concentration increasing. Compared with the pure SrTiO_3 ceramics, the relative dielectric constant could be enhanced to 3,681 (at 1 kHz and room temperature)with dielectric loss less than 0.02 when x = 0.02. The good stability of ε_r under 0-20 kV/cm is beneficial to applying in high voltage conditions. Two sets of relaxation peaks of Sm doped SrTiO_3 ceramics are observed which are all related to the oxygen vacancies. The medium-temperature relaxation is ascribed to the coupling of oxygen vacancies with strontium vacancies and the origin of high-temperature relaxation is the motion of oxygen vacancies.