关键词: 吸波材料, LaMnO₃掺杂, 复介电常数, 复磁导率

Abstract:

La0.8Sr0.2Mn0.86Fe0.14-xCoxO3（ X = O. 01, 0. 02, 0. 03 ） crystal powders were synthesized via the sol-gel method, and the crystal structure of the product was characterized by means of XRD. Then, the complex permittivity and permeability of the product in the frequency range of 2 - 18 GHz were measured using a microwave vector network analyzer. Moreover, the curves describing the relationship between the microwave reflectivity and the frequency were obtained according to the measured data. The results show that, with a thickness of 1.80 mm, La0.8Sr0.2Mn0.86Fe0.13Co0.01O3 is of an absorption peak height of 27. 9 dB and an absorption bandwidth in 2 -18 GHz of 5.3 GHz, while with a thickness of 2.00mm, the height decreases to 26dB and the bandwidth to 4. 9GHz. According to the tangents of both electric loss and magnetic loss angles, the microwave absorption attributes to both the dielectric and the magnetic loss, especially the former. It is also indicated that the doping of Fe and Co changes the double-exchange of Mn^3＋--O--Mn^4＋ system and the electromagnetic parameters of the material, thus improving the microwave-absorbing properties.

Key words: microwave-absorbing material, LaMnO₃ doping, complex permittivity, complex permeability