Effect of Lanthanum Doping on Microstructural, Dielectric and Magnetic Properties of Mn0.4Zn0.6Cd0.2LaxFe1.8-xO4 (0.0 ≤ x ≤ 0.4)

The effect of doping lanthanum (La) ions on the structural, morphological, dielectric and magnetic properties of Mn–Zn–Cd nanoferrites are reported in the present study. The samples with composition as Mn0.4Zn0.6Cd0.2LaxFe1.8-xO4 (0.0 ≤ x ≤ 0.4) were prepared using the conventional co-precipitation route. The analysis of XRD patterns revealed the formation of spinel structure along with the presence of a secondary LaFeO3 phase at the grain boundaries with increasing La content in the composition. The decrease in lattice parameter with doping of La ions supported the observed increase in the theoretical X-ray density of the samples. The SEM and TEM images revealed a slightly bigger crystallite size than obtained from XRD data analysis due to the intergranular diffusion stimulated by a higher sintering temperature of 1300 °C. FTIR analysis revealed the increase in band position from 574.05 to 590.20 cm−1 in the high-frequency band range with increasing La ion doping. The prepared nanoferrite samples were tested to obtain dielectric and magnetic properties over the frequency range of 7.5 × 104 Hz and 3.0 × 107 Hz. A significant increase in dielectric constant and dielectric loss tangent values was observed with increasing La content. On the contrary, the initial permeability and permeability loss values decreased with increasing La content due to the replacement of Fe3+ ions on the octahedral site by La3+ ions.