Detailed investigation of Mn-substituted Zn ferrites for microwave applications up to 6 GHz

Mn-substituted Zn ferrites with chemical formula Zn 1−x Mn x Fe 2 O 4 (0.0, 0.1, 0.2, 0.3) were synthesised via sol-gel auto-combustion. The structural analysis reveals that tetrahedral lengths decrease while octahedral lengths increase due to strong affinity of large ionic radii Mn for octahedral sites as compared to Zn. Scanning electron microscopy reveals that the grain size of all the ferrites lies in the range 200–250 nm. Hysteresis loops of all samples show the coercivity to be several hundred Oersted, indicating the soft magnetic nature of spinel ferrites. High-frequency parameters like complex permittivity and permeability, direct conductivity and loss tangent were measured against varying frequencies (∼ 6 GHz) for a selected sample.