Phase composition or material morphology, which one plays the pioneering role in promoting microwave absorption and hyperthermia

Morphology and phase control have enabled better tuning of microwave absorbing, hyperthermia, and optical characteristics. The phase and morphology of materials determine fundamental factors, including permeability, permittivity, impedance matching, magnetic properties, and optical performance. The nature of each phase individually determines microwave absorption performance based on its permeability and permittivity. Meanwhile, nucleated phases and their modification, based on intrinsic characteristics, as well as size and morphology properties, by improving polarization-relaxation loss, magnetic properties, impedance matching, metamaterial characteristics, multiple reflections and scatterings, microcurrents, and conductive networks, pave the way for microwave attenuation. In the hyperthermia scenario, the crystalline phase offers pioneering magnetic performances such as saturation magnetization and coercivity; on the other hand, the morphology based on the Snoek limit and regulated spin pinning, crystal defect, and unsaturated coordinate states suggests the magnetic characteristics and optimizes the hyperthermia performance. Optimizing these features can significantly improve microwave absorption and hyperthermia performance. Here, the morphology of the CuFe₂O₄ structure was manipulated, and various crystalline phases, including Cu, CuO, Fe₂O₃, and Fe₃O₄, were loaded into the structure using innovative precursors and synthetic routes. To fabricate the final composite, polyethersulfone (PES) was used as a polarizable microwave-absorbing medium, thereby regulating the microwave absorption and shielding performance. The phase-modified sample (Fe₂O₃/CuO/PES) demonstrated the highest reflection loss (RL) of -95.43 dB at 25.35 GHz and an effective bandwidth of 3.24 GHz, with a thickness of 1.95 mm. Particularly, morphology-modified CuFe₂O₄/PES covered the k-band with a thickness ranging from 0.35 to 0.75 mm. The radar cross sections (RCS) results demonstrated that the phase and morphology modification promoted the cloaking capability of the samples. An impressive RCS reduction of 37.61 dBm² was achieved at an angle of 33 degrees. More importantly, the architected samples demonstrated considerable electromagnetic interference shielding effectiveness (EMI SE) and specific absorption rate in hyperthermia therapy.