Synthesis, morphological and electromagnetic evaluations of Ca doped Mn spinel nanoferrites for GHz regime applications

Calcium (Ca) doped manganese (Mn) spinel nanoferrites with the composition of Ca1-xMnxFe2O4 where x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 are synthesized by sol-gel self-ignition route. XRD, FESEM and FTIR are employed to investigate the cubic crystallite structure, phase, morphology, grain size and vibrational bands respectively. Functional bands and phase of the Ca-doped Mn nanoferrites were evaluated using FTIR. The values of the force constants were increased with Ca substitution in Mn ferrites. The systematic effects of Ca on the microstructure and morphology were also examined using FESEM. The electromagnetic analysis including complex permittivity, permeability, conductivity and loss tangent of the Ca doped Mn nanoferrites in the frequency ranges of 1 GHz-6 GHz are studied using VNA with coaxial probe. Conductivity varies by increasing the Ca substitution in Mn spinel ferrites. This may be due to the electron and polaron hopping between Fe3+ and Fe2+ ions. The quality factor shows highest values after 2.3 GHz frequency region for all the Ca doped nanoferrites. The reasonable conduction mechanism into the higher frequency region may be suited for Mn-Ca nanoparticles as a commercially industrial material for microwave high frequency GHz regime applications.