Structural and electrical properties of 0.56Pb(Ni1/3Nb2/3)O3-0.10Pb(Zn1/3Nb2/3)O3-0.34PbTiO3 ceramics prepared by different ceramic processings

The ternary system of 0.56Pb(Ni1/3Nb2/3)O3-0.10Pb(Zn1/3Nb2/3)O3-0.34PbTiO3 (0.56PNN-0.10PZN-0.34PT) ceramics were prepared by conventional solid-state reaction method via straight mixed oxide method, columbite precursor method and B-site oxide mixing route. X-ray diffraction (XRD) measurement demonstrated that both the tetragonal and rhombohedral phases coexist in the B-site oxide mixing route prepared ceramics accompanied by the largest content of perovskite phase of 95.18%. The 0.56PNN-0.10PZN-0.34PT ceramics prepared by the straight mixed oxide method and the B-site oxide mixing route exhibit rather homogeneous microstructure. As a comparison, in the columbite precursor method prepared ceramics nebulous granules and octahedral or other polyhedral morphology grains are observed. All the sintered ceramics exhibit diffused ferroelectric phase transition where the dielectric response peaks are broad, diffused and strongly frequency dependent. However, the temperature of dielectric maximum (Tm) increases greatly from 398.0 K of the 0.56PNN-0.10PZN-0.34PT ceramics prepared by the B-site oxide mixing route to 423.3 K of the ones prepared by the straight mixed oxide method. Saturated and symmetric P-E hysteresis loops are observed in all the sintered ceramics, where the B-site oxide mixing route prepared ceramics exhibit large value of remanent polarization (Pr) of 17.13 μC/cm2 and the least value of coercive field (Ec) of 11.99 kV/cm. Piezoelectric constant (d33) exhibits the largest value of 449 pC/N for the ceramics prepared by the B-site oxide mixing route. Such results are related to the phase composition, density and porosity of the ceramics.