Highly coercive strontium hexaferrite nanodisks for microwave absorption and other industrial applications

Abstract Highly coercive strontium hexaferrite (SHF) nanodisks are synthesized for the first time via the polymer solution method. The structural, microstructural, thermal, magnetic, electromagnetic, and microwave absorption properties of the synthesized SHF nanodisks are closely investigated. The Rietveld refinement of the XRD results confirms the crystal structure of the prepared SHF nanodisks as hexagonal with a space group of P63/mmc having cell dimensions of a, b = 5.8808 A and c = 23.0424 A with χ2 = 2.48. The thermo-gravimetric behaviour of the synthesized sample shows that the stable phase of SHF nanodisks is formed after 761 °C. The morphological study shows the average diameter and the thickness of the prepared SHF nanodisks as 70 nm and 27 nm, respectively. The SHF nanodisks possess a saturation magnetization of 55.90 emu/g and magnetic coercivity of 10.34 KOe. Such a high coercivity may be attributed to the formation of single domain SHF nanoparticles with nanodisks morphology and high magneto-crystalline anisotropy. The maximum reflection loss of the SHF nanodisks/epoxy nanocomposites in X-band is found to be −17.44 dB with −10 dB absorption bandwidth of 2.42 GHz for 2 mm thick sample. The proposed SHF/epoxy nanocomposite shows high reflection loss with improved absorption bandwidth even for a very thin sample, which makes it a potential candidate as the radar absorbing material for stealth and other strategic applications. Additionally, the synthesized magnetic SHF nanodisks can also be used for industrial applications such as wastewater treatment, MEMS and permanent magnets, the magnetic recording media for data storage, etc.