The microwave absorption properties of La0.8Sr0.2Mn1−yFeyO3 nanocrystalline powders in the frequency range 2–18 GHz

La1−xSrxMn1−yFeyO3 nanocrystalline powders were prepared by the sol–gel method as a microwave absorption material. The reflectance, the dielectric loss tan δe and the magnetic loss tan δm of the samples were calculated according to the data of electromagnetism parameters measured by a microwave vector network analyzer in the frequency range 2–18 GHz. The dielectric loss tan δe and the magnetic loss tan δm had a step-change at a certain frequency so that the superiority of dielectric loss change into the superiority of magnetic loss, which indicated that anti-ferromagnetic clusters in the material change into ferromagnetic clusters by absorbing quantum of microwave electromagnetic field when the frequency of incident microwave reaches a certain value. The effective absorption bandwidth higher than 10 dB reached 6.2 GHz. As a result, the La0.8Sr0.2Mn1−yFeyO3 has shown useful applications as a microwave absorption material.