Characterization, structural and magnetic properties of the as-prepared Mg-substituted Cu-nanoferrites

Graphical abstract: RT Mössbauer spectra of the as-prepared Cu_1−xMg_xFe₂O₄ nanoparticles. - Highlights: • Cu_1−xMg_xFe₂O₄ nanoparticles were prepared by the co-precipitation method. • They behaved superparamagnetically and their crystallite size was decreased with x. • Sample patterns and spectra, results and parameters showed x dependence. • Saturation magnetization was dependent on x and R. • Strain, Debye temperature and stiffness constant were changed nonlinearly with x. - Abstract: The as-prepared Cu_1−xMg_xFe₂O₄ nanoferrites, 0 ⩽ x ⩽ 1, were synthesized using the co-precipitation method. The samples were characterized using the X-ray diffraction, transmission electron microscopy, infrared (IR) and Mössbauer spectroscopy and vibrating sample magnetometer. This study proved that the samples have single-phase cubic spinel structure, nanometric size and superparamagnetic behavior. The nanoparticle and crystallite size (R) showed a dependence on the Mg ion content x. The Mössbauer spectra were analyzed and assigned to two magnetic subpatterns and/or two quadrupole doublets due to Fe ions among the tetrahedral A-sites and octahedral B-sites. Six IR absorption bands were observed and assigned to the corresponding vibration modes. The saturation magnetization showed decrease against x and proved dependence on R. The lattice constant, hopping lengths, strain, site characteristic bands and B-site force constant showed x dependence, whereas oxygen parameter and A-site force constant did not. The site ionic radii and edges, density, porosity, Debye temperature, stiffness constant, hyperfine interaction and magnetic parameters were deduced and discussed as functions of x and the cation distributions were estimated