Temperature-dependent electromagnetic properties of rare-earth Gd3+ ion-doped bismuth ferrite ceramics

Microwave absorption materials play a critical role in stealth technology and electromagnetic protection. Bismuth ferrite (BiFeO3, BFO) as a multiferroic material with spontaneous polarization and a high curie temperature shows great potential in the field of microwave absorption. However, its single intrinsic relaxation mechanism limits its ability to meet the requirements in both excellent microwave absorption performance and temperature stability. In this work, Gd3+ doped Bi1-xGdxFeO3 (BGxFO, x = 0, 0.05, 0.15) ceramics were synthesized for achieving high-efficiency microwave responses. The Gd3+ incorporation drives a rhombohedral-to-pseudo-cubic phase transition, reduces both grain and domain sizes, and introduces lattice defects. These effects collectively modulate dielectric and magnetic losses. As a results, the BG15FO sample achieves a minimum reflection loss (RLmin) of -19.5 dB at a thickness of 1 mm, which is maintained at 200 °C. Impedance-matching analysis confirms that Gd3+ doping significantly enhances the high-temperature microwave absorption stability. This work systematically elucidates how Gd3+ doping controls the absorption stability of BFO ceramics over a wide temperature range (room temperature to 200 °C). It establishes a rare-earth doping strategy for optimizing ferroelectric-based electromagnetic absorbers, and provides a design guideline for high-performance microwave-absorbing materials.