Unconventional high permittivity and relaxor like anomaly in (Sr, Ce, Pr)TiO_3 solid solution

摘要

In this study, non-stoichiometric solid solution, Sr_(1-1.5(x+y)Ce_xPryTiO_3 abbreviated as (Sr, Ce, Pr)TiO_3 (with 0.05 ≤x≤0.35 and y = 0.05, sintered in N_2/H_2 with 99% N_2 and 1% H_2) were prepared via a conventional solid-state method. By introducing (Ce_(0.25)Pr_(0.05))~(3+/4+) on the A-site, the structure symmetry of the ceramic could be reduced, confirming cubic to tetragonal phase transition. Using Rietveld refinement and electron diffraction (TEM), the tetragonal phase was assigned to P4/mmm space group which posses a center of symmetry (centrosymmetric tetragonal unit cell). A small opening of hysteresis loop at higher Ce doping is assumed to be a caused by defect dipoles and conductivity. The dielectric anomalies were observed in all compositions, therefore, we assume that they are not related to structural phase transition but rather to some conductivity processes.