An investigation of structural and magnetic properties of Ce-Nd doped strontium hexaferrite nanoparticles as a microwave absorbent

Ce-Nd-substituted M-type strontium hexaferrite nanoparticles, Sr(CeNd)(x/2)Fe12-xO19 (SCNH)(x = 0, 0.5, 1, 1.5, 2) can be successfully synthesized using co-precipitation method. The synthesized nanocomposites are characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscope (FESEM), vibrating sample magnetometer (VSM). The vector network analyzer (VNA) were used to analyze microwave absorption property. For comparison, the microwave absorption properties of the samples were measured by two simulation and metal back methods. The XRD and FT-IR analysis confirmed the existence of the M-type strontium hexaferrite phase in all samples. FESEM shows that the morphology of the particle in all of the samples was roughly hexagonal shape and they had uniform distribution. The VSM results indicated that increasing amounts of doped Ce3+ and Nd3+ reduced saturation magnetization (Ms) and coercivity (H-c). The minimum Hc for Sr (CeNd)(x/2) Fe12-xO19 (SCNH) (x = 0, 0.5, 1, 1.5, 2) was 2700 Oe. The VNA results showed that by measuring the permittivity and permeability at 5 mm thickness and simulating the RL for <5 mm thicknesses the maximum RL would be obtained as -8.7 dB at d = 2.5 mm and f = 11 GHz in X = 2 sample. While using the metal back approach by direct measurement of RL from S-11 at d = 2.5 mm thickness, results in maximum reflection loss of -37 dB at 9.62 GHz with 1.93 GHz bandwidth in X = 2 sample. This could be attributed to microstructural non-uniformities, which have not been taken into account in RL simulating method, while the direct calculation of RL at each specific thickness (by measuring the S-11) yields more realistic results. Totally the results showed that Ce-Nd doped strontium hexaferrite nanoparticles are suitable candidates as microwave absorbers.