Effect of Ca2+ doping and annealing temperature on the structure, morphology and magnetic behavior of CaxCo1-xFe2O4/SiO2 nanocomposites

•Pure CaFe2O4 displays the smaller, while CoFe2O4 presents larger nanoparticles.•The particle diameter increases with the Co2+ content increase.•The tridymite content decrease with increasing Co2+ content.•CaFe2O4 exhibits ferromagnetic, CoFe2O4 shows superparamagnetic-like behavior.•Thermal treatments at 800 °C, higher magnetic coercivities are obtained than at 1200 °C.