Green synthesis of chromium substituted calcium hexaferrite nanoparticles for high-frequency applications

For the first of its kind, Cr3+-substituted calcium hexaferrite (CaCrxFe12-xO19 (x=1, 3, 5 and 7)) nanoparticles (NPs) were synthesized via a facile, economical, eco-friendly lemon juice extract mediated green solution combustion method. The samples were calcined followed by characterization. The Bragg reflections confirm the formation of a single phase M-type hexaferrite crystal structure. No other impurity or mixed phases are observed even after the substitution of Cr3+ to the host matrix. Meanwhile, the crystallite size decreases from 29.44 to 19.92nm with an increase in the substitution of Cr3+ ions. The surface morphological analysis shows the presence of agglomerated irregularly shaped NPs. The direct energy band gap estimated using Wood and Tauc's relation depicts the decrease in energy band gap from 2.98 to 2.74eV with an increase in the substitution of Cr3+ ions. These Cr3+-substituted calcium hexaferrite NPs were predicted to be useful in high-frequency applications based on structural, dielectric, and magnetic studies.