Multifunctional behavior of acceptor-cation substitution at higher doping concentration in PZT ceramics

The Fe-doped PZT, Pb (Zr, Ti)_1-xFe_xO₃, ceramics have gathered plenty of attention because of the interplay of ferroelectric and ferromagnetic properties. In the present study, we report the properties of Pb(Zr_0.52Ti_0.48)_1-xFe_xO₃, x = 0, 0.05, 0.10, 0.15 and 0.20, prepared by conventional solid state reaction route with varying Fe³⁺ doping concentrations. Study of X- ray diffraction patterns confirmed the tetragonal crystal structure with reduction in tetragonality and unit cell size with doping. It also showed formation of secondary magneto-plumbite phase at higher doping concentrations. The SEM micrographs exhibited decrease in grain size with increase in doping concentration (for x > 0.05). The increase in oxygen vacancies and the formation of secondary magneto-plumbite phase and Fe³⁺–VO²⁻–Fe³⁺ defect dipole complexes introduced with the acceptor (Fe³⁺) doping, caused clamping of the domain walls and hence reduced the room temperature dielectric constant as the doping concentration was increased. The coexistence of electrical polarization and magnetic moment at room temperature in all PFZT compositions confirmed the multiferroic characteristic in the ceramic samples. Electric polarization (P_r) and coercive fields (E_c) decreased with increase in Fe³⁺ concentration in PFZT sample. However, magnetization (M) and magnetic coercive fields (E_c) increased with the increasing Fe³⁺ concentration due to the dominant effect of F-center exchange mechanism in Fe³⁺–VO²⁻–Fe³⁺ and formation of ferromagnetic secondary magneto-plumbite phase.