Effects of Co content and annealing temperature on the structure and optical properties of CoxMg1−xAl2O4 nanoparticles

► Effects of Co content and temperature on the cation distribution in CoxMg1−xAl2O4 nanoparticles are studied. ► Mg2+ and Co2+ ions occupy both tetrahedral and octahedral sites in the nanoparticles. ► The secondly octahedral Al3+ ions are observed besides the above two coordination sites. ► Inversion parameter of the samples decreases with the increase of annealing temperature and cobalt content. ► Optical properties of the nanoparticles are discussed on the basis of the structural results.