Effect of La-Na Doping in Co-Ti Substituted Barium Hexaferrite on Electrical and X-Band Microwave Absorption Properties

Lanthanum and sodium co-substituted barium hexaferrite Ba(1-2x)La (x) Na (x) Fe10CoTiO19 (x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25) samples were prepared using a conventional solid state reaction route. Structural, morphological, electrical and microwave absorption properties of synthesized hexaferrites were investigated using various instruments including x-ray diffractometer (XRD), scanning electron microscope (SEM), impedance analyzer and vector network analyzer. Single phase formation was confirmed by XRD analysis. Unit cell volume decreased with increase in concentration. Average grain size as estimated from SEM micrographs lies in 0.73-1.15 mu m range. The DC resistivity decreased with increase in La-Na concentration. The dielectric parameters were measured in the 10 kHz-1 MHz frequency range. At lower frequencies, dielectric constant (epsilon') and tangent loss (tan delta) values were high, which decreased with increases in frequency. Electromagnetic and microwave absorption properties were evaluated theoretically in the X-band (8.2-12.4 GHz) for different sample thicknesses. The microwave absorption analysis suggests that the sample with composition Ba0.80La0.10Na0.10Fe10CoTiO19 could be an effective microwave absorbing candidate for microwave applications in the X-band frequency range.