Tunable Microwave Absorption Properties in Ni–Zn-Substituted BaCoTiFe₁₀O₁₉

Ni–Zn-substituted BaCoTiFe₁₀O₁₉ were successfully prepared by a sol-gel combustion method. The grain size of samples is about 150–800 nm ,and the grains first increase and then decrease with increasing x. Through XRD analysis, all diffraction peaks correspond to the BaTiCoFe₁₀O₁₉ and no other phase signal is detected. With x = 0.3, the saturation magnetization (M_s) is biggest (66.7 emu/g) and its coercivity (H_c) is 172.3 Oe. The curves μ^″ − μ^′ have distorted semicircles, and each semicircle has an extremum. Each extremum of μ^″ − μ^′ curve corresponds to a peak of μ^″ curve and has response to reflection loss (RL), which is further illuminated. When x = 0.3, the widest bandwidth of RL ≤−10 dB is 6.13 GHz (9.68–15.81 GHz) at d = 2.6 mm. The RL curve closely relates to distorted semicircle of μ^″ − μ^′ curve, and the relation is also deeply illuminated, which is beneficial to study absorption materials.