| The wide application of microwave absorbing material in military and civil life makes it an important branch of modern scientific research.Recently, study on the microwave absorbing properties of doped LMO has become more and more popular.This paper firstly discusses the influence of the doping concentration of AM (AM=Li,Na,K) on the structure of doped La1-xAMxMnO3.Then the absorbing performance of doped La1-xAMxMnO3 in the range of 3.95-12.4GHz is investigated.All the samples were prepared by solid state reaction method.XRD,EDS,SEM were used to characterize the structures of samples and VNA to measure the permeability and permittivity of samples.The results show:(1)When the calcination temperature is 1200℃, the doping concentration of AM in La1-xAMxMnO3 samples should be under 20%,or other structures could be introduced.(2) La1-xAMxMnO3 samples with different doping concentrations and different matching thicknesses would diverse in microwave absorbing performance.This diversity may be ascribed to the influence of different doping elements and doping concentrations on the double exchange effect (DE).The specific studies and comparisons reveal that:A) When matching thickness is 3.0mm, the maximu RL of La0.85Li0.15MnO3 sample is -36.7dB while La0.95Li0.05MnO3 is-32.7dB.B) The bandwidth of La0.80Na0.20MnO3 sample below-10dB is 2.7GHz and the maximum RL(-42.7dB) is obtained at 7.68GHz with a thickness of 3.0mm. C) La0.85K0.i5MnO3 sample shows the best absorbing performance in 3.95-12.4GHz compared with other K-doped LMO samples. The maximum RL can reach-38.4dB at 9.02GHz and the effective absorbing bandwidth (below-10dB) is 2.6GHz with the matching thickness of 2.5mm. |
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