This study investigates how transition metal selection influences the multifunctional properties of
T0.40Mn0.60Fe2O3 nanocomposites (NCs), where T represents Cu, Sn, Co, or Ni. Using hydrothermal method, we
prepared four NC variants and systematically characterized their structural, mechanical, magnetic, and dielectric
properties through XRD, FTIR, VSM, and BDS. X-ray diffraction revealed distinct phase compositions: Cu and Co
NCs contained monoclinic T2Mn3O8, rhombohedral Fe2O3, and cubic Fe3O4 phases, while Sn and Ni NCs formed
cubic TMn2O4 instead of the monoclinic phase. Mechanical properties varied significantly, with Cu/Sn NCs
showing larger crystallites but lower porosity compared to Co/Ni NCs. All compositions exhibited roomtemperature
ferromagnetism, with Co/Ni NCs demonstrating superior saturation magnetization (47.13 and
39.27 emu/g versus 7.45 and 30.54 emu/g for Cu/Sn) but lower coercivity (372–13.2-G versus 1.33×
103–55.99 G). Dielectric measurements showed frequency-dependent behavior, with relaxation peaks appearing
only in Sn/Co/Ni NCs. The AC conductivity followed the order Cd > Sn > Cu > Ni > Co, while impedance
analysis revealed grain boundary effects dominating in Ni/Co NCs. These property variations stem from the
interplay between magnetic moments (Co/Ni) and non-magnetic ions (Cu/Sn), enabling tailored applications:
high-Ms Co/Ni NCs for spintronics, and high-Hc Cu NCs for permanent magnets, while Sn NCs show promise for
high-frequency dielectric applications.