Absorption of microwaves in La1-xSrxMnO3 manganese powders over a wide bandwidth

We present the frequency dependence of microwave-absorbing properties of La 1-xSrxMnO3 (x=0.4, 0.5, 0.6, and 0.7) powders at room temperature. The abso rbing properties change gradually with x in the frequency range of 8-12 GHz . The optimal absorption can be achieved for a x=0.4 sample and its microwa ve loss peak value is about 25 dB. Further experimental results show that t he absorption can be attributed to magnetic and dielectric losses and the m icrowave loss peak corresponds to the maximum dielectric loss tangent tan d elta (e) near 10.5 GHz. Furthermore, the absorbing properties of the oxides mixed with carbonic fiber and Y-type planar hexagonal ferrite have been ru dimentarily studied. Results show that these additives greatly enhance the microwave-absorbing properties of the oxides. (C) 2001 American Institute o f Physics.