Modified structure and optical properties of multiferroic Pb(Zr_0.53Ti_0.47)_x(Fe_0.5Nb_0.5)_(1−x)O₃ ceramics

The Pb(Zr_0.53Ti_0.47)_x(Fe_0.5Nb_0.5)_(1−x)O₃ (xPZTFN) multiferroic ceramics synthesized by a solid state reaction method have been investigated by means of structural characterizations and optical measurement. All the samples show polycrystalline perovskite structures with dense microstructures, but exhibit a gradual transition behavior from cubic to tetragonal structure with increasing x. The xPZTFN (0≤x≤0.2) ceramics have an average crystal structure described as the centrosymmetric cubic perovskite, whereas x≥0.4 ceramics are consistent with a non-centrosymmetric tetragonal structure. Coexistence of both cubic and tetragonal symmetries is observed for x=0.3. Raman spectroscopy analysis corroborates the change in average structure with the x but also show the local crystal symmetry for 0≤x≤0.2 ceramics to deviate from the idealized cubic perovskite. Optical absorption spectra indicate that Pb(Zr_0.53Ti_0.47)O₃ (PZT) doping has an effect on the energy band structure. The band gap (E_g) of xPZTFN (0≤x≤0.7) ceramics is in the range of 2.08–2.33 eV, much smaller than the 3.21 eV E_g of the PZT material. This result shows that the modification of optical property can be achieved by manipulating the composition in xPZTFN materials.