Structural, magnetic and dielectric properties of lanthanum substituted Mn0.5 Zn0.5Fe2O4

Mn0.5Zn0.5LaxFe2-xO4 (x = 0.0, 0.025, 0.050, 0.075 and 0.10) ferrites have been synthesized using coprecipitation method. Effect of substitution of La3+ on structural, magnetic and dielectric properties of Mn0.5Zn0.5LaxFe2-xO4 was studied. Structural properties have been investigated using X-ray diffraction (XRD) and morphological by transmission electron microscopy (TEM). XRD analysis revealed the formation of cubic spinel structure. Different structural parameters like lattice parameter, crystallite size, interionic distances, average cationic radii, bond angles and bond lengths have been calculated and compared with various theoretically predicted parameter TEM images confirmed that particle size decreases with La content. Magnetic behavior of synthesized sample was studied employing vibrating sample magnetometer (VSM). It was noted that as x increased from 0 to 0. maximum magnetization showed decreasing trend from 34.57 emu/gm to 15.34 emu/gm (noted at 15000 and Curie temperature from 193 degrees C to 147 degrees C at constant field of 500 G. Real (epsilon') and imaginary part (epsilon '') dielectric constant, dielectric loss (tan delta), ac conductivity (sigma(ac)), real (Z') and imaginary part (Z '') of impedance were studied with frequency (0.1 Hz-1 MHz) and composition. epsilon', epsilon '', tan delta and sigma(ac) were observed to decrease wit substitution of La3+ ions. This variation can be attributed to the hopping of electrons between Fe2+ ions an Fe3+ ions at octahedral sites. Cole-cole plot showed a single semicircular arc for Mn0.5Zn0.5LaxFe2-xO4 clear indicating the dominant effect of grain boundary in conduction.