Coexistence of relaxor behavior and ferromagnetic order in multiferroic Pb(Fe0.5Nb0.5)O-3-BiFeO(3)solid solution

The coexistence of relaxor ferroelectric behaviour and ferromagnetic ordering in a single-phase material is of both fundamental interest and practical potential for applications. To study this rather unusual phenomenon, a series of multiferroic solid solutions of (1 -x)Pb(Fe0.5Nb0.5)O-3-xBiFeO(3)(PFN-BFO, with 0 <= x <= 0.6) were synthesized in the form of ceramics using the solid-state reaction technique and its relaxor and magnetic properties were systematically characterized in this work. Structural refinements based on X-ray diffraction data at room temperature reveal the phase evolution from a monoclinic phase withCmsymmetry to a pseudo-cubic phase withPm3msymmetry with increasing BFO content. The ferroelectric phase transition and relaxor behaviour were investigatedviavariable-temperature dielectric spectroscopy. A temperature-composition phase diagram was constructed in terms ofT(C),T-m, the Burns temperature (T-B) and freezing temperature (T-f), which delimits a ferroelectric phase (FE) forx< 0.025 atT= 0.25 atT <= T-N, and a paramagnetic phase (PM) for all the compositions atT >= T-N. The coexistence of relaxor behaviour and ferromagnetic ordering at room temperature makes the PFN-BFO solid solution a particularly interesting multiferroic material.