Praseodymium dysprosium co-doped M-type strontium ferrite: Intentionally manufacturing heterophase growth to improve microwave absorption performance

When excessive praseodymium and dysprosium ions are doped with M-type strontium ferrite, heterophases with different magnetic and electrical properties will be formed. We use this to intentionally induce different heterogeneous growth in the Pr-Dy co-doped strontium ferrite system. While maintaining the dielectric loss of the main phase, the produced heterogeneous phase acts as a companion for dielectric and magnetic losses. The synthesized SrFe12-2xPrxDyxO19 ferrite demonstrates its potential as a microwave absorbing material, exhibiting excellent absorption effects over a wide range of Pr-Dy doping (x = 0.05-1.5). The XRD results show that the synthesized materials include both pure M-phase and coexistence of M-phase and heterophases, and the generated heterophases are mainly perovskite type ferrite and garnet type ferrite. SEM and EDS results indicate that Pr-Dy co-doping can significantly refine the grain size, reduce the grain size of the main and heterophases, and lead to a decrease in oxygen content. The XPS analysis shows that some praseodymium ions are in the Pr4+ oxidation state, leading to the existence of Fe2+ ions and oxygen defects (Od). The VSM results indicate that at different calcination temperatures, the saturation magnetization decreases and the coercivity shows an increasing trend as the Pr-Dy doping amount increases. Pr-Dy doping not only increases the dielectric and magnetic losses of the M phase, but also generates heterophases that can enhance the dielectric and magnetic losses of the material, jointly improving the absorption effect. This results in excellent absorption performance of the material within a large range of praseodymium dysprosium doping contents (x = 0.05-1.5, RLmin = -52.51 dB, EABmax = 4.81 GHz).