Microwave absorbing properties of La_1-x Ba _x MnO₃ (x=0.1,0.2,0.3,0.4,0.5) nano-particles

Abstract

Electromagnetic wave absorbing materials have always been a research hotspot in military and civil fields. La1-x Ba x MnO3 nanocrystalline powders were prepared by sol-gel method. XRD analysis shows that La1-x Ba x MnO3 is a single perovskite structure, and the lattice constant changes with the doping amount. SEM analysis shows that La1-x Ba x MnO3 is basically spherical with an average particle size of about 80 nm. The relationship between the complex permittivity and permeability with microwave frequency was measured by microwave vector network analyzer. According to the measured data, the microwave reflectivity and loss factor of the sample were calculated, and the microwave loss mechanism of the sample was discussed. The results show that x has a great influence on the absorbing properties of La1-x Ba x MnO3. When x is 0.2 and the thickness is 1.6mm, the absorption bandwidth above 10dB reaches 2.1GHz and the maximum absorption value is 25dB. The microwave loss of La1-x Ba x MnO3 mainly comes from the dielectric polarization loss of perovskite materials, it also comes from conductivity loss, magnetic loss and interface polarization loss due to Ba doping and nano effect.