M-type Ba0.4Pb0.6Fe12-xCoxO19 hexaferrites were synthesized at 950°C using citrate gel auto-combustion, showing a range of cobalt substitutions (x = 0.00 to 0.40) for potential lossless applications. XRD analysis unveiled the development of the M-phase alongside PbM and hematite. Microstructural examination highlighted stacked hexagonally shaped platelet clusters, confirmed by TEM images showing polycrystalline features at x = 0.3. All samples displayed hard magnetic behavior with a maximum saturation magnetization at x = 0.10 (55.427 A m2/kg) and varying coercivity (0.058 T to 0.390 T). Notably, cobalt substitution significantly influenced dielectric properties, where ac conductivity increased till x = 0.10, followed by a reduction till x = 0.40, mirroring the trend in dielectric constant. Overall, the low loss tangent across all compositions indicates promising prospects for lossless applications. #CobaltSubstitution #Hexaferrites

https://www.sciencedirect.com/science/article/abs/pii/S0272884221019118?via%3Dihub