Structure and dielectric property of (1 - x)Pb(Fe1/4 Sc1/4Nb1/2)O3-xPbTiO3 ceramics prepared via a B-site oxide mixing route

Phase pure perovskite (1 - x)Pb(Fe1/4Sc1/4Nb1/2)O3-xPbTiO3 (PFSN-PT) ferroelectric ceramics were prepared by conventional ceramic processing via a B-site oxide mixing route. The PFSN-PT ceramics sintered at 1180 0C for 2 h exhibit rather homogeneous microstructure and improved dielectric properties as compared with those synthesized by the wolframite precursor method accompanied by large relative density except 0.5PFSN-0.5PT and 0.4PFSN-0.6PT. With the increase in the content of PbTiO3 (PT), the crystal structure of PFSN-PT changes from a rhombohedral perovskite structure with some distortion to a tetragonal one accompanied by an increase in tetragonality (defined as the ratio of cell parameter c/a) from 1.0256 of 0.6PFSN-0.4PT to 1.0534 of 0.2PFSN-0.8PT. Furthermore, the ferroelectric phase transition of PFSN-PT changes from a diffused phase transition of relaxor ferroelectrics to a nearly first-order phase transition of normal ferroelectrics with the increase in PT content. The value of the dielectric constant maximum (εm) and the temperature of the dielectric maximum (Tm) also increases almost linearly.