Radio-Absorbing Composite Materials Based on La0.7Sr0.3MnO3

In the frequency range 3.2-12 GHz the absorption of microwave energy was measured by new composite materials, which are xLSMO/yGeO2/(1-x-y)NaF (LiF) glass ceramics, where x, y are the mass fractions of the composite components, x =0.7-0.95 , y=0.05-0.20. Conductivity measurements were performed, structural and microstructural features of materials were studied. It has been found that concentrations of germanium oxide and fluorides significantly affect the degree of absorption of microwave energy by samples. Absorption spectra close to linear ones at levels from 0-3 dB to 12-14 dB were obtained in the whole investigated frequency range for various materials. Some increase in the absorption (5-10%) of energy by these composite materials under the influence of a weak (H≈300 kOe) constant magnetic field was revealed. The spectra of the integral radiation of the electric field were measured with the composites with the lowest conductivity. Prospective areas of work have been outlined for obtaining broadband radio-absorbing composite materials.