Effect of BiFeO3 Doping and Annealing Temperature on the High-Temperature Dielectric Relaxation Properties in BaTiO3-SrTiO3 Lead-Free Ceramics

Lead-free xBiFeO(3)-(1-x)BaTiO3-SrTiO3 solid-solution ceramics are synthesized and their structure and dielectric and ferroelectric properties are studied. It is observed that the dielectric relaxation process (marked as Region I) triggered by polar nanoregions (PNRs) related to Fe2+/Fe3+ valences may cover the relaxation process induced by oxygen vacancies (OVs, marked as Region II) at 1150 and 1200 degrees C. The changes in relaxation peak heights show that with the increase of annealing temperature and BiFeO3 content, the PNR concentration increases while OV concentration decreases. Cole-Cole diagram analysis indicates that dielectric relaxations are likely based on changes in grain interior, grain boundary, and the increased electrode/ceramic interface as the doping content increases. The possible causes of relaxation behavior dependence are analyzed in detail.