Effect of Ca²⁺ exchange at Ba²⁺ site on the structural, dielectric, morphological and magnetic traits of BaM nanohexaferrites

The effect of Ca²⁺ exchange at the Ba²⁺ site for reporting their structural, dielectric, magnetic traits and morphological behaviour of Ba_1−xCa_xFe₁₂O₁₉ (x = 0.0–0.5) nanohexaferrites synthesized by sol–gel auto-combustion technique (SGACT), have been evaluated. XRD plots confirm the single-phase purity of the synthesized samples upto x = 0.2, but beyond that, a secondary phase (α-Fe₂O₃) was observed in all the synthesized samples. The FESEM studies exhibit that the average size of the grains increases from 140 nm to 276 nm as the amount of the Ca²⁺ ions doping increases. The increasing sharpness of the Raman peaks, as the content of the dopant ion increases (upto x = 0.2), reveals an increase in nanocrystallinity of prepared samples. The values of coercivity (H_c) lie in the range of 5043–5290 Oe. The saturation magnetization (M_s) reaches its highest value of 72.38 emu/g for x = 0.2 specimen. The dielectric constant (ε^') of Ba_1−xCa_xFe₁₂O₁₉ (x = 0.0–0.5) hexaferrites was improved as a function of calcium content upto x = 0.3, whereas, it starts to decrease with frequency. Therefore, the study shows that the synthesized samples with superior values of M_s, H_c, and ε^', along with low dielectric loss (tanδ) can be used for manufacturing nanomaterials which act as permanent magnets.