Effects of sintering temperature on structural, magnetic and microwave absorption properties of Ni0.5Zn0.5Fe2O4 ferrites

• Ni 0.5 Zn 0.5 Fe 2 O 4 ferrites were synthesized by the sol-gel auto-combustion method. • The microwave absorption properties can be adjusted by changing the sintering temperature. • The maximum absorption bandwidth reached 9.55 GHz at a thickness of 2.5mm. • Possible mechanisms of microwave absorption properties have been analyzed. Ni 0.5 Zn 0.5 Fe 2 O 4 ferrites were prepared by the sol-gel auto-combustion method and sintered at 1150°C, 1250°C, 1350°C and 1450°C. Structural, magnetic, and microwave absorption properties were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectra, Vibrating sample magnetometer and vector network analyzer, respectively. Sintering temperature has a remarkable effect on the concentration of both Fe 2+ and oxygen vacancies and further influence the permittivity and permeability. The excellent microwave absorption properties are obtained at the sintering temperature of 1350°C, and its effective absorption bandwidth reaches 9.55 GHz from 3.67 to 13.22 GHz at a thin thickness of 2.5 mm. It is notable that the two reflection loss peaks of Ni 0.5 Zn 0.5 Fe 2 O 4 ferrites appeared at both low and high frequency regions. The peak at low frequency is associated with the great magnetic loss tangent (>1) and the peak at high frequency satisfies the quarter-wavelength matching model. The microwave absorption performance of Ni 0.5 Zn 0.5 Fe 2 O 4 ferrites was attributed to both dielectric and magnetic mechanisms while the magnetic part dominates.