Exchange-coupled Ni_0.5Zn_0.5Fe₂O₄/SrFe₁₂O₁₉ composites with enhanced microwave absorption performance

Using sol-gel self-propagating combustion technique, Ni_0.5Zn_0.5Fe₂O₄/SrFe₁₂O₁₉ (NZFO/SFO) composites were successfully prepared at 1000 °C for 2 h and characterized by XRD, FTIR, SEM, TEM, VSM and VNA. It was observed that the grain size of NZFO was decreased with increase of SFO content. The magnetic properties and microwave absorption performance were closely related to the mass ratio of NZFO and SFO phase as well as thickness of sample. The sample with the mass ratio of 1:3 exhibited superior magnetic properties with Mr value of 30.5 emu·g⁻¹ and Hc value of 3300 Oe. Meanwhile, when the thickness of sample was 4 mm, RL_min of −47.0 dB was obtained at 6.2 GHz and the bandwidth (RL < −10 dB) reached 6.4 GHz from 2.9 GHz to 9.3 GHz, which confirmed excellent broadband absorption performance of NZFO/SFO composites.