Magnetic and structural studies of trivalent Co-substituted Cd–Mn ferrites

•Co3+-substituted Cd–Mn ferrites were prepared by the solid state reaction.•The lattice constant, grain size, specific surface area and strain were x dependent.•IR frequencies, force constants and Debye temperature showed x dependence.•x was affected the threshold frequency and magnetic properties.•The bond length showed effect on the site frequency and force constant.

Series of polycrystalline Cd0.4Mn0.6CoxFe2−xO4 ferrites, 0≤x≤1, were prepared by solid state reaction method. The samples were characterized by inductive coupling plasma, X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectra and vibrating sample magnetometry. This study proved that all samples have single-phase cubic spinel structure. The true lattice constant, saturation magnetization, magnetic moment and trend of grain size and IR band νA showed decrease against x, whereas the trend of crystallite size, threshold frequency, Debye temperature, IR bands ν1 and ν2 and force constants F1 and F2, coercivity, anisotropy constant and residual magnetization showed increase. The IR analysis proved existence of Fe2+, Co2+, Fe4+, Co4+ and/or Mn4+ ions amongst the crystal sublattices. The characteristic bands ν1 and ν2 and force constants F1 and F2 showed decrease versus the tetrahedral- and octahedral-site bond length, respectively. The strain, specific surface area, refractive index, velocity, jump rate and remnant magnetization proved dependence on Co3+ ion content x.