The effect of cobalt substitution in crystal structure and vibrational modes of CuFe2O4 powders obtained by polymeric precursor method

•We synthesized mixed spinels by polymeric precursor method.•We investigated the structural and vibrational properties of the mixed.•We investigated the synthesis condition effects in these properties.•We proposed a complete phonon description for CuFe2O4 and CoFe2O4 spinels. In this work Co–Cu mixed spinel Co1−xCuxFe2O4 powders were obtained by polymeric precursors method at several annealing temperatures between 700 and 1200°C. The samples were characterized by means of X-ray powder diffraction, confirming the ideal inverse spinel structure for CoFe2O4 sample and the tetragonal distorted inverse spinel structure for CuFe2O4 sample. Based on FWHM evaluation, we estimated that crystallite sizes varies between 27 and 37nm for the non-substituted samples. The optical-active modes were determined by infrared and Raman spectroscopies. The phonon spectra showed a local tetragonal distortion for mixed samples.