LAUSR

Abstract In this study, to effectively broaden the absorption bandwidth of M-type barium ferrite (BaM) in frequency range 2–18 GHz, Zr4+-Ni2+ ions gradient-substituted BaM samples were synthesized via secondary heating the mixtures of homogeneous-substituted Ba(ZrNi)0.6Fe10.8O19 and Ba(ZrNi)0.7Fe10.6O19. Effects of primary and secondary heat treatment on electromagnetic (EM) parameters of gradient-substituted BaM were investigated in detail. Permittivity values of samples are mainly controlled by primary heat treatment, enhancing with increasing temperature, whereas magnetic loss range is enlarged by improving primary and secondary heat treatment. As a result, the frequency range with μ" value > 0.3 reaches to 6.84 GHz for the sample “1400–1200 °C”. Enhanced dielectric and magnetic losses contribute high attenuation constant over wide frequency range, finally resulting in broad absorption bandwidth of 6.24 GHz at matching thickness of 2.8 mm. The bandwidth improved by 21% and 44% compared to that of original Ba(ZrNi)0.6Fe10.8O19 and Ba(ZrNi)0.7Fe10.6O19, respectively. This study sheds new light on the preparation of broadband absorbing materials.