Magnetic and Microwave Properties of Barium Hexaferrite Ceramics Doped with Gd and Nd

Substituted barium hexaferrite nanoparticles with the chemical formula BaFe12-x (GdNd) O-x/2(19) (x = 0-2, in steps of 0.5) were prepared by a co-precipitation method. Phase identification and crystal structure of the nanoparticles were investigated by x-ray diffraction. The morphology of the nanopowders was investigated by field-emission scanning electron microscopy. Results from Fourier-transform infrared spectroscopy enabled identification of stretching and bending modes. Magnetic properties were measured by use of a vibrating sample magnetometer. The results revealed that saturation magnetization and coercivity decreased as x increased. Investigation of microwave-absorption properties, by use of a vector network analyzer, revealed that the maximum reflection loss of substituted Ba-ferrite of thickness 1.6 mm reached -41.8 dB at a frequency of 4.3 GHz and a bandwidth of 7.5 GHz, with reflection loss being >-20 dB. From these results it was concluded that the composites had good potential as absorbers in the gigahertz frequency range.