Achieving strong microwave absorption capability and wide absorption bandwidth through a combination of high entropy rare earth silicide carbides/rare earth oxides

Developing electromagnetic（EM） wave absorbing materials with low reflection coefficient and optimal operating frequency band is urgently needed on account of the increasingly serious EM pollution. However, the applications of common EM absorbing materials are encumbered by poor high-temperature stability, poor oxidation resistance, narrow absorption bandwidth or high density. Herein, the strong EM absorption capability and wide efficient absorption bandwidth of high entropy ceramics are reported for the first time, which are designed by a combination of the novel high entropy（HE） rare earth silicide carbides/rare earth oxides（RE3 Si2 C2/RE2 O3）. Three HE powders, i.e., HERSC-1(HE(Tm0.2 Y0.2 Dy0.2 Gd0.2 Tb0.2)3 Si2 C2),HERSC-2 HE(Tm0.2 Y0.2 Dy0.2 Gd0.2 Tb0.2)3 Si2 C2/HE(Tm0.2 Y0.2 Dy0.2 Gd0.2 Tb0.2)2 O3) and HERSC-3(HE(Tm0.2 Y0.2 Dy0.2 Gd0.2 Tb0.2)3 Si2 C2/HE(Tm0.2 Y0.2 Dy0.2 Gd0.2 Tb0.2)2 O3), are synthesized. Although HERSC-1 exhibits a limited absorption effect(the minimum reflection loss（RLmin） is-11.6 d B at 3.4 mm) and a relatively narrow effective absorption bandwidth（EAB） of 1.7 GHz, the optimal absorption RLminvalue and EAB of HERSC-2 and HERSC-3 are-40.7 d B（at 2.9 mm）, 3.4 GHz and-50.9 d B（at 2.0 mm）, 4.5 GHz,respectively, demonstrating strong microwave absorption capability and wide absorption bandwidth.Considering the better stability, low density and strong EM absorption effect, HE ceramics are promising as a new type of EM absorbing materials.