Abstract:

(1-x)Sr(Fe_1／2Nb1_／2)O_3-xPbTiO₃(SFN-PT) ferroelectric ceramics were prepared by the conventional solidstate reaction method via the columbite precursor technique. XRD measurement confirmed that the synthesized SFN-PT ceramics are of pure perovskite structure. With the increase of themole fraction  ofPbTiO₃ (PT), the crystal structure of the synthesized SFN-PT ceramics changes from  a rhombohedral structure to a tetragonal one. Dielectric response also changes from diffused and broad dielectric peaks to relatively sharp and almost frequency independent ones accompanied by an  increase of the temperature of dielectric maximum (Tm). A small content of MnO2 or Li2CO3 doping can greatly decrease the dielectric loss of the SFN-PT ceramics. Furthermore, the abnormal increase of dielectric constant and loss tangent in the paraelectric region is accordingly suppressed. Typical P-E hysteresis loops are observed in the SFNPT ceramics although the remanent polarization (Pr) is small. MnO2 and Li2CO3 doping can greatly decrease coercive field (Ec) of the SFN-PT ceramics accompaniedby large increase of Pr. The piezoelectric constant d₃₃ of the SFN-PT ceramics is small which changes from 10 pC/N to 22 pC/N.

Key words: strontium iron niobate-lead titanate; ferroelectrics; perovskite; electrical property