Effects of O2 and N2 Sintering Atmospheres on Electric Properties of 0.9srtio3–0.1nife2o4 Composite Ceramics

The 0.9SrTiO(3)-0.1NiFe(2)O(4) (STO/NFO) composite ceramics sintered at O-2/N-2 atmospheres were investigated. The N-2-sintered STO/NFO (STO/NFON) had a larger microstrain (0.092(47)%) than the O-2-sintered STO/NFO (STO/NFOO) revealed by the Rietveld refinement and the Williamson-Hall analysis. The maximum polarization of STO/NFON increased to similar to 7.1 mu C/cm(2), but the larger leakage current in STO/NFOO resulted in a 20% larger false remanent polarization value. Moreover, STO/NFON presented a lower activation energy (E-a, 1.22 eV), which implied more oxygen vacancies (V-O(center dot center dot)). The amount of Ti3+ ions (60%) in STO/NFON increased as well, which formed defect dipoles [Ti4+center dot e-V-O(center dot center dot)-Ti4+center dot e] and fixed V-O(center dot center dot). The composite of STO/NFON also showed decreased V-O(center dot center dot) content (similar to 53%) owing to the fixing effect and presented low leakage current, increased impedances, and the improved ferroelectric hysteresis loop. The anomaly dielectric constants peaks indicated different conductivity mechanisms related to V-O(center dot center dot), and the STO/NFON ceramic possessed a low rate of dielectric loss.