Fe2Cd1-xMnxO4 (x= 0, 0.25, 0.5, 0.75, 1) spinel ferrite nanoparticle samples were synthesized using a flash auto-combustion technique and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The inspection of dielectric and magnetic properties of the prepared ferrites was carried out by using broadband dielectric spectroscopy (BDS) and vibration sample magnetometer (VSM) measurements, respectively. X-ray diffraction analysis verified the formation of the main cubic phase with space group Fd3m and a decrease in lattice constants with the increase in Mn-content. FTIR study revealed the two characteristic absorption bands of spinel ferrites and their dependence on Mn-content was investigated and explained. Elastic moduli such as Longitudinal, transverse and mean elastic wave velocities (𝑉𝑙 , 𝑉𝑡 𝑉𝑚), bulk modulus (𝐵), rigidity modulus (𝐺), Young modulus (𝐸) and calculated Debye temperature (θD) have been studied and found to decrease with the increase in Mn-content. SEM analysis revealed nanoparticles agglomeration of uniform grains with increasing in the average grain size as Mn-content increased. The VSM measurements showed an increase in saturation magnetization (Ms) accompanied by a decrease in coercivity (Hc) as Mn-content increased. Dielectric investigations showed very high values of permittivity and dielectric loss at lower frequencies reflecting the combination of exchange of electrons between ferrous and ferric ions and ions’ transport. The ac-conductivity showed a plateau that yields the dc-conductivity (σdc) at lower frequencies followed by a characteristic frequency (νc) at which it tends out to follow a power law. The relation between these two parameters confirms the empirical BNN-relation.
