Low temperature ferromagnetic ordering and dielectric properties of Bi1-xDyxFeO3 ceramics

Polycrystalline Bi1−xDyxFeO3 (x=0.03, 0.05, 0.07, 0.10, and 0.12) ceramics were synthesized by solid state reaction method. Rietveld refinement reveals that all the samples crystallize in the rhombohedral structure with non-centrosymmetric R3c space group. Substitution induced suppression of the spiral spin structure and Dy3+-Fe3+ interaction enhanced the room temperature magnetization. Temperature dependent magnetization curves suggest that the magnetic coupling between Dy3+-Fe3+ and Dy3+-Dy3+ ions enhanced at low temperatures range for x=0.07–0.12 samples. ESR study indicated enhanced magnetic properties due to change in magnetic behavior of Fe3+ ions. The change in the Fe-O-Fe bond angle corresponds to the increase in Neel transition temperature with increasing Dy concentration. The dielectric properties are improved with increasing Dy content in BiFeO3. The grain and grain boundary contributions decrease with increase in temperature for all samples, indicating a negative temperature coefficient of resistance.