Effect of Mn and Zn doping on natural resonance frequency of strontium U-type hexaferrite and its performance as electromagnetic wave absorbers

In the present work, substitution of strontium U-type hexaferrite with the composition of Sr4Mn2-xZnxFe36O60, (x = 0.5,0.6,0.8, and 1.0) was prepared via high energy ball milling (HEBM) and sintered at 1100 degrees C. The phase, microstructure, magnetic, dielectric and electromagnetic wave absorbing properties of U-type strontium hexaferrite composites were measured using XRD, FESEM, and Vector Network Analyzer in the frequency range of 8-18 GHz (X-band and Ku-band). MnZn doping was found to shift the natural resonance of the materials by affecting its magnetocrystalline anisotropy. The reflection loss (RL) indicated that the composite possessed good microwave-absorbing properties with U-type strontium hexaferrite (Sr4Mn2-xZnxFe36O60) of x = 0.8 resulted in high minimum RL value for all thickness of 1 mm and two peaks at approximately - 32.50 and - 41.50 dB at 14.00 and 15.60 GHz, with bandwidth of 0.60 and 0.80 GHz for losses less than - 10 dB. (C) 2021 Elsevier B.V. All rights reserved.