Microwave absorption properties of Nd_(o.7)Sr_(0.3)MnO_3 prepared using high-energy ball milling

摘要

The permittivity and permeability behaviors of composites made from the high-energy ball milled Nd_(o.7)Sr_(0.3)MnO_3 and paraffin wax have been studied in 2-20 GHz. An optimal reflection loss of -24 dB is reached at 16.4 GHz with a matching thickness of 2.4 mm. The excellent microwave absorption properties of the as-milled sample are attributed to the interfacial polarization of nanocrystal/amorphous phases and intrinsic electric dipole polarization, which enhance the dielectric losses. Permeability is found to have negative imaginary parts within 12-20 GHz. The main contribution of the microwave absorption should result from the dielectric loss.