Magnetodielectric effect in Co3O4 nanoparticles grown within a silica glass

► Co3O4 nanoparticles grown within a silica glass. ► The nanoparticles exhibit ferromagnetic hysteresis at temperature less than 15 K and superparamagnetism above this temperature. ► Thermal expansion mismatch causes tensile strain at glass-crystal interface. ► The above-mentioned strain causes a loss of center of symmetry of Co3O4 phase resulting in ferroelectric behaviour. ► The nanocomposites exhibit reasonably high magnetodielectric effect.