Remarkable microwave absorption efficiency of low loading ratio of Ni0.25Co0.25Ti0.5Fe2O4/SrCoTiFe10O19/Cu composite coated with polyprrole within polyurethane matrix

NiCoTi spinel ferrite, SrCoTi hexagonal ferrite and copper microparticles were coated with polypyrrole (PPY) using in situ chemical oxidative method. The resulted microwave absorbing material was introduced into polyurethane matrix. XRD patterns indicated the successful preparation of spinel and hexagonal ferrites. SEM micrographs showed the semi-spherical morphology of the prepared composite. The magnetic properties have been investigated using VSM. The microwave absorber with 20%w/w loading percentage exhibits the best microwave absorption performance (bandwidth under -10 dB of 3 GHz and reflection loss of -24 dB at the matching frequency 9.75 GHz and thickness of 1.8 mm). The measurements of permittivity and permeability reveal that the dielectric loss mechanism is the predominant in the current absorber. The measured reflection loss using free space method also indicates the superior performance of the sample with 20%w/w loading percentage.