LAUSR

Abstract Iron deficient Mn-Zn ferrite was prepared by doping the microwave induced pyrolysis char of wastewater sludge. The effects of doping with different dosages of pyrolysis char on the crystallization phase, micromorphology, crystal microstructures, electromagnetic parameters and microwave absorbing properties were investigated. The iron deficient ferrite samples with microwave sintering at a temperature of 900 °C had a spinal structure, and the main crystallization phase was Zn 0.75 Mn 0.75 Fe 1.5 O 4 . The crystal grains with the dopants of 20 wt% were homogeneous, and the average grain size was about 36.80 nm. The crystal of ferrite with dopants of 20 wt% had a clear grain boundary, and the crystallinity degree reached 94.76%. Moreover, the electromagnetic parameters (permittivity and permeability) of Zn 0.75 Mn 0.75 Fe 1.5 O 4 ferrites were changed due to the dopants improving the electromagnetic wave absorbing properties. The electromagnetic wave reflection loss of the Zn 0.75 Mn 0.75 Fe 1.5 O 4 ferrite samples with the dopants of 20 wt% increased to −4.2 dB.