Microwave absorption and magnetic properties of LiZnMn ferrites doped with Mg

Ferrite has been extensively studied due to its wide range of applications. In present work, Li_0.4-0.5xZn_0.2Mn_0.1Mg_x-0.1Fe_2.4-0.5xO₄ (x = 0.1, 0.15, 0.2, 0.25, 0.3) were synthesized by sol-gel auto-combustion method. X-ray diffraction and infrared spectroscopy confirmed the formation of a cubic spinel structure. The lattice constant was found to increase with higher x values, while density, grain size and microstrain decreased correspondingly. The saturation magnetization and coercivity showed slight decreases after Mg doping, whereas the initial permeability slightly increased. The Curie temperature declined from 433 °C at x = 0.1 to 395 °C at x = 0.3. Mg doping also reduced the optimal matching thickness of microwave-absorbing materials to 3 mm. Mg-LiZnMn absorber is lighter in weight than LiZnMn. Notably, the sample with x = 0.15 exhibited excellent absorption characteristics from 8.2 GHz to 13.1 GHz, with a reflection loss (RL) of −32 dB. These findings suggest that an appropriate concentration of Mg doping can enhance the impedance matching of the materials, thereby improving their microwave absorption performance.