Structural and magnetic characterization of Co2+ substituted Ni-Zn ferrite nanoparticles synthesized by refluxing co-precipitation and their potential application as gas sensors

•Ni0.3Zn0.7-xCoxFe2O4 nanoferrites were synthesized by refluxing co-precipitation method.•XRD and FTIR results confirmed the formation of cubic spinel structure.•VSM and Mössbauer results revealed enhancement of magnetic properties with increasing Co content.•Strong correlation between then inverse susceptibility and unit cell was observed.•Ni-Zn ferrites doped with Co revealed high sensitivity and real time response to propanol gas.