Development of doped Ba–Sr hexagonal ferrites for microwave absorber applications: Structural characterization, tunable thickness, absorption peaks and electromagnetic parameters

In this work, we report microwave absorption characteristics of Ba_0·5Sr_0·5(CoCr)_xFe_(12-2x)O₁₉ hexaferrite prepared by a two route ceramic technique. The effect of Co²⁺-Cr³⁺content on structural, complex permittivity/permeability and reflection loss properties in Ba_0·5Sr_0·5Fe₁₂O₁₉ ferrite has been studied. X-ray diffraction confirmed the magnetoplumbite phase in the compositions. The dual absorption peaks were revealed in x = 0.8 composition with reflection loss of −52.09 dB at 8.78 GHz and 5.6 mm thickness. The absorption peaks were found to shift to low frequency with an increase in thickness. Composition x = 0.6 displayed the bandwidth to thickness ratio of 6.5 and a percentage bandwidth of 32.37% at 1.7 mm thickness and 10.13 GHz. The doping of Co²⁺ and Cr³⁺ reduced thickness, increased absorption, and bandwidth which is attributed to electromagnetic parameters, input impedance, quarter wavelength theory, and eddy current loss. The investigated performance parameters of prepared compositions indicate good scope for absorber applications.