Preparation and characterization of doubly substituted microwave absorbing material by sol-gel technique for super high frequency applications

Rare earth Dy3+ and divalent Mn2+ elements substituting W-type hexagonal ferrites Ba1−xDyxZn2Fe16−yMnyO27 (x = 0, 0.02, 0.06, 0.1 and y = 0, 0.1, 0.3, 0.5) were prepared by sol-gel method. The thermo- gravimetric analysis (TGA) and differential scanning calorimetry (DSC) was carried out to find the temperature at which single phase can be obtained. XRD patterns indicate the presence of the single phase for all the synthesized samples with the absence of any extra peak due to unreacted material and secondary phases. The occurrence of absorption bands at low wave numbers (563 and 446 cm−1), can be assigned to the stretching vibration of metal and oxygen ions in FTIR spectra, which also confirms the single hexagonal phase for prepared material. The grains are of platelet like structure, which enhances the microwave absorption properties of hexagonal ferrites. The synthesized material exhibits the minimum reflection loss of −20.9 dB at 11.8 GHz frequency, which reflects the applications of this material in super high frequency devices. The microwave conductivity of the material increases with frequency.