Phase transition enhanced electromagnetic wave absorption in Cs(Pb,Fe,Co,Ni,Mn)Br3‐based high‐entropy compounds.

To address challenges such as signal interference and crosstalk, the development of novel materials with the ability of electromagnetic absorption (EMA) is imperative. In this study, the composition of the B‐site of CsPbBr3 was fixed for all samples Pb0.2Fe0.2Co0.2Ni0.2Mn0.2 with varying A/B ratios of 1:1, 1:2, and 1:3. We achieved good EMA properties for the Cs1(Pb0.2Fe0.2Co0.2Ni0.2Mn0.2)3O3, including a minimum reflection loss of 75 dB at 10.2 GHz and a 2.5 mm thickness, accompanied by an exceptionally wide effective bandwidth of 8.8 GHz. X‐ray diffraction, transmittance electron microscopy, and X‐ray photoelectron spectroscopy, etc. were used to characterize the structure, morphology, and EMA‐associated properties of CsMBr3. The presence of high entropy was validated through meticulous analysis using Rietveld and grazing‐incidence wide‐angle scattering patterns. The magnetic permeability, dielectric constant, polarization, and attenuation loss were improved with a high‐entropy ratio of 3 within the 30–50 nm crystals. Notable lattice distortion within PbBr6 and phase transition within high‐entropy alloying are the driving forces behind these enhanced EMA characteristics. [ABSTRACT FROM AUTHOR]