Yttrium-doped strontium hexaferrite particles for microwave absorption application in X-band

Yttrium-doped strontium hexaferrites particles, Sr_1−xY_xFe₁₂O₁₉ (x = 0.1, 0.2 and 0.3), are developed using auto combustion method. The doping resulted in partial replacement of Fe³⁺ ions with Fe²⁺ ions which is found to be an effective method to tune microwave absorption properties of strontium hexaferrite. The XRD spectrum confirmed the formation of ferrite with no secondary phase present. All the developed samples showed platelet-like morphology with an average particle size of 590 nm for the undoped sample. The average particle size decreased with the increase in the Y doping. The hysteresis loop revealed that the saturation magnetization increased with increase in doping concentration of yttrium in strontium hexaferrite. On the contrary, coercivity decreased from 296 to 209 G due to decrease in the magnetic anisotropy of the ferrite. The frequency-dependent dielectric and magnetic loss tangent are increased with the increase of Y doping. The sample with x = 0.3 showed the best impedance matching with the free space with an average normalized impedance of 1.28. The attenuation constant was also found to be maximum i.e., 85.6 for x = 0.3. The reflection loss is investigated for a frequency range from 8.2 GHz to 12.4 GHz (X-band) and indicated maximum reflection loss of -18.91 dB with -10 dB bandwidth of 2.18 GHz for x = 0.3 for coating thickness of 2.6 mm. The current study presents the Yttrium-doped strontium hexaferrites, Sr_0.7Y_0.3Fe₁₂O₁₉, as a strong candidate for the microwave absorption application.