Sol-gel auto-combustion method for the synthesis and investigation of Zr⁴⁺/Cu²⁺ doped barium calcium M-type hexaferrites

In this work, we synthesized barium calcium M-type hexaferrites (BaCaM) and examined the effect of Cu and Zr doping on its physical and chemical changes. The sol-gel auto-combustion method (SGACM) was employed for the preparation of Ba_0.8Ca_0.2Zr_xCu_xFe_12-2xO₁₉ (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0). The phase purity and structural parameters of Ba_0.8Ca_0.2Zr_xCu_xFe_12-2xO₁₉ (BaCaZrCuM) were determined using the Rietveld refinement of XRD data. FESEM data revealed the microstructure of the grains and grain sizes. IR absorption bands around 400 cm⁻¹ and 800 cm⁻¹ confirm the presence of octahedral and tetrahedral Fe-O sites, respectively, in the samples. Bands in the Raman spectra broadened and decreased in intensity with increasing dopant concentration, consistent with the successful incorporation of dopants within the lattice structure. M-H plots revealed that the magnetization saturation value initially increased up to x = 0.4 (55.06 emu/g) and then decreased up to x = 1.0 (42.13 emu/g). The value of H_c decreased with increasing Cu and Zr concentration. The ε (dielectric constant) decreased with increasing frequency and decreased at low frequencies with increasing dopant concentration. Dielectric loss was also found to be reduced at higher frequency in the x = 0.4 sample, thus showing different behavior than other concentrations. These materials have potential applications in magnetic recording, permanent magnets and electromagnetic interference (EMI) shielding. (Figure presented.)