Mossbauer and magnetic studies of multiferroic Mg0.95Mn0.05Fe2-2xTi2xO4 system

A series of polycrystalline multiferroic system Mg0.95Mn0.05Fe2-2xTi2xO4 is prepared by a solid-state reaction route. The effect of Ti+4 substitution in Mg0.95Mn0.05Fe2-2xTi2xO4 has been studied using x-ray diffraction (XRD), Mossbauer spectroscopy, isothermal magnetization hysteresis, temperature dependent dc susceptibility, and temperature dependent dielectric measurements. Structural transformation from cubic spinel to tetragonal has been revealed from the XRD analysis. From the analysis of Mossbauer spectra, the decrease in hyperfine field at both tetrahedral and octahedral sites has been observed as a function of the concentration of Ti+4 ions, which has been explained on the basis of a supertransferred hyperfine field. The appearance of the paramagnetic doublet within the sextet is due to the interaction of the electric field gradient (EFG) with the quadrupole moment of Fe-57 nucleus and the decrease in magnetic interaction between Fe ions with Ti dilution. The variation in the quadrupole splitting indicates that the EFG changes with the increase in the substitution of Ti+4 ions. Isothermal hysteresis loop shows the ferromagnetic behavior of Mg0.95Mn0.05Fe2-2xTi2xO4 and the saturation magnetization is decreased with the increase in the substitution of Ti+4, which is explained by the weakening of the exchange interaction in the system. The dielectric measurements of these samples exhibit ferroelectric transition depending upon the concentration of the Ti+4. (C) 2006 American Institute of Physics.