ELECTROMAGNETIC WAVE PROPERTIES IN THE MICROWAVE FREQUENCY OF COMPOSITE La1.5Sr0.5NiO4/CoFe2O4

Abstract

La_1.5Sr_0.5NiO₄ is known to be a typical dielectric with huge dielectric constant and weak paramagnetic properties at room temperature. The weak magnetic moment together with the very large imbalance between the dielectric constant and the permeability lead to weak absorption of electromagnetic waves due to the absence of the contribution of the magnetic field loss component. In order to improve the magnetic field loss and balance the magnetic and dielectric parameters, the CoFe₂O₄ ferrite was gradually added to obtain the La_1.5Sr_0.5NiO₄/CoFe₂O₄ composite. The reflection loss RL was determined in the microwave frequency range from 4 to 18 GHz using a vector network analysis measurement system. The maximum value obtained is down to -31.5 dB at 12.6 GHz for sample x = 10% in open circuit mode and -26 dB at 6.4 GHz for sample x = 15% in short circuit mode with an Al plate. Partial substitution of the magnetic material at an appropriate concentration into La_1-xSr_xNiO₄ is expected to obtain dielectric/ferrite composite materials that strongly absorb electromagnetic waves in the desired frequency region.