Electrical and Magnetic Properties of Nanosized Mg0.2Mn0.5Ni0.3AlyFe2-yO4 Ferrites

Electrical and magnetic behavior of Mg(0.2)Mn(0.5)Ni(0.3)AlyFe(2-y)O(4)(y=0.0-0.3) spinel ferrites synthesized by citrate precursor method sintered at 1200 degrees C are reported. Samples were characterized by X-ray diffraction technique at room temperature. Lattice parameter 'a', saturation magnetization M-s, retentivity M-r, Bohr magneton n(B) and remnant ratio R=M-r/M-s are seen to decrease whereas coercivity H-c shows increasing trend with increasing Al3+ content. Anisotropy field H-K(A) increases with aluminium content, which along with M-s enable calculation of magneto-crystalline anisotopy constant K-1, which increases with increasing Al3+ content. The compositional variations of hysteresis parameters like M-s, H-c, M-r and R reveals that grains in composition studied are of multidomain type. A significant reduction in value of initial permeability and relative loss factor (RLF) was observed with increase of Al3+ ions. DC electrical resistivity decreases with increase in temperature exhibiting semiconductor like behavior. Activation energy is determined from dc electrical resistivity measurements. High dc resistivity and very low RLF makes these ferrites suitable particularly for high-frequency applications where eddy current losses are required to be low.