Magnetic and microwave absorption properties of SrZnCoFe16O27 powders synthesized by solution combustion method

ZnCo-substituted strontium W-type hexaferrite (SrZnCoFe16O27) has been prepared by solution combustion synthesis method. The effects of fuel content (ϕ = 0.75, 1 and 1.5) on phase evolution, microstructure and magnetic properties were characterized by X-ray diffractometry, infrared spectroscopy, electron microscopy and vibrating sample magnetometry techniques. Fourier transform infrared analysis and theoretical calculations were conducted to determine and control the concentration of metal citrates in solution precursors. Single phase SrZnCoFe16O27 powders with the large platelet-like particles were achieved at ϕ = 1.5 following calcination at 1200 °C, while the M-type hexaferrite and spinel ferrite phases were formed at ϕ < 1.5. With the increase of fuel content, the saturation magnetization increased from 64.8 to 76.8 emu/g and coercivity firstly increased from 355 to 585 Oe and then decreased up to 34.1 Oe. The microwave absorption measurements in X-band (8-12 GHz) exhibited the maximum absorption of −33.6 dB at 10.4 GHz with an absorption bandwidth of more than 2.5 GHz at −20 dB for the powders synthesized at ϕ = 1.5.